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Tuberculosis in the Workplace (2001)

Chapter: Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities

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Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

D
Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities

Keith F.Woeltje, M.D., Ph.D.*

SUMMARY

In response to nosocomial outbreaks of tuberculosis among patients and health care workers, the Centers for Disease Control and Prevention (CDC) released tuberculosis control guidelines in 1990. These were later expanded and revised in 1994. The CDC guidelines rely on a series of controls: administrative, engineering, and personal respiratory protection. Administrative controls include the prompt identification and isolation of patients who may have pulmonary tuberculosis. Engineering controls include proper ventilation for isolation rooms and other areas, possibly supplemented by ultraviolet germicidal irradiation or high-efficiency particulate air (HEPA) filtration. Personal respiratory protection consists of some form of mask or respirator worn by a health care worker to minimize the risk of inhaling infectious airborne droplet nuclei.

Implementation of control measures in outbreak settings has been shown repeatedly to stop the outbreak. Although many steps may be started at once, the bulk of the evidence suggests that the CDC controls are hierarchical, in that administrative controls are most important (if tuberculosis is not suspected, the other controls will not be initiated), followed by the engineering controls, and lastly, the type of personal respiratory equipment. In nonoutbreak settings having these measures in place almost certainly reduces the risk for health care workers and patients of nosocomial exposure to tuberculosis. However, studies trying to correlate health care worker infections with adherence to tuberculosis

*  

Assistant Professor of Medicine, Section of Infectious Diseases, Medical College of Georgia, Augusta.

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

controls in low- to moderate-risk situations have had mixed results. This may be due to underlying differences in the baseline purified protein derivative (PPD) conversion rates in different hospitals. In addition to the adoption of the whole guidelines, a number of studies have focused on parts of the guidelines. This is particularly true of administrative controls. It is in this area where the most variability in practice will arise, particularly in designing criteria for patient isolation, owing to the wide differences in patient populations seen at different hospitals.

Although compliance with the guidelines in the early 1990s was suboptimal, a number of studies show significant improvements in guideline compliance. However, there are many areas that still have considerable room for improvement, particularly in the education of health care workers about tuberculosis. Information on implementation of the guidelines outside of the inpatient setting of acute-care hospitals is scarce. Some evidence exists that many emergency departments are making progress.

The cost of implementation of the guidelines can be substantial, but many of these costs are one-time facility improvements. Although the ongoing costs of a tuberculosis control program can be substantial, these programs may be relatively cost-effective compared with the costs incurred in evaluating patients or healthcare workers exposed to a nonisolated tuberculosis patient.

INTRODUCTION

Summary of 1990 and 1994 CDC Guidelines

After decades of declining rates of tuberculosis in the United States, case rates leveled off and then increased in the late 1980s and early 1990s (1, 2). A number of factors led to the reversal of the previous trend: decreased public health infrastructure, the human immunodeficiency virus (HIV) epidemic, and an influx of immigrants from areas where tuberculosis is endemic (3). The problem was compounded by the fact that many physicians and other healthcare workers had very little experience with tuberculosis. They often did not suspect the diagnosis when a patient with the disease first presented and, even if suspected, often had little appreciation for the infection control issues involved. Almost inevitably, a number of nosocomial outbreaks of tuberculosis occurred, including outbreaks involving multidrug-resistant tuberculosis (MDR tuberculosis) (4, 5, 6, 7, 8, 9, 10). In December 1990, CDC published “Guidelines for Preventing the Transmission of Tuberculosis in Health-Care Settings, with Special Focus on HIV-Related Issues” (11) in response to these outbreaks. Subsequently, these guidelines were expanded and refined with the publication in October 1994 of “Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Facilities, 1994” (12).

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

The 1994 CDC guidelines include recommendations for assignment of responsibility for tuberculosis control. A risk assessment for the facility (and potentially for individual wards and areas within the facility) is suggested. This risk assessment takes into account the number of tuberculosis patients seen at the facility, the number of tuberculosis patients in the surrounding community, and whether or not there is evidence of increased health care worker PPD skin test conversions. The extent to which other control actions are taken would then depend on the risk of the facility. For example, a baseline PPD test for new employees is recommended for essentially all facilities, but the frequency of routine serial testing would be determined by the risk assessment. The guidelines also suggest health care worker education consistent with the duties/training of the employee. Good cooperation with local health departments is also stressed. Although the bulk of the guidelines are targeted to acute-care hospitals, tuberculosis control in other settings such as dental clinics, physicians’ offices, and long-term-care facilities are also briefly discussed.

The core of the 1994 CDC guidelines is a series of control measures for handling patients suspected of having tuberculosis. Three categories of controls are described: administrative, engineering, and personal respiratory protection. Administrative controls include prompt recognition of patients who may have tuberculosis with subsequent rapid isolation of these patients, efficient diagnostic evaluation, and criteria for releasing patients from isolation. Other administrative controls include practices such as keeping patients on tuberculosis isolation in their room unless medically necessary. Engineering controls involve primarily ventilation, tuberculosis isolation rooms should have negative pressure, ≥ six air changes per hour (ACH), and exhaust air directly to the outside (or HEPA filter the air before recirculation if this is not possible). Engineering controls also include having good general ventilation, especially in areas where patients may congregate. Ultraviolet germicidal irradiation (UVGI) may be used as an adjunct to both general ventilation and tuberculosis isolation room ventilation. Finally, the guidelines discuss personal respiratory protection for health care workers who are likely to be exposed to tuberculosis aerosols (e.g., while in a tuberculosis isolation room). The respirator should be compliant with Occupational Safety and Health Administration (OSHA) requirements, and used as part of a comprehensive respiratory protection program.

Focus of Review

The author was directed to “prepare a technical background paper reviewing the literature and data on the effects of the CDC guidelines on tuberculosis control in health care facilities.” This paper is being written as background for an Institute of Medicine report on occupational expo-

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

sure to tuberculosis. Although the 1994 guidelines do include employee tuberculin skin testing programs and personal respiratory equipment, this paper will not address these particular aspects because the topics will be covered in other background papers. One important exception is that employee PPD test conversion rates will be discussed as a marker for the effectiveness of different tuberculosis control plans.

Although the 1994 CDC guidelines are the most current, as summarized above, these guidelines are an extension and revision of the 1990 guidelines. Thus, this paper will review the impact of implementation of policies following both sets of guidelines. As with the guidelines, this paper will focus primarily on the inpatient, acute-care setting. This is partly out of necessity, as there is a paucity of data on implementation of the guidelines in other settings.

Methods

To find papers for review, a MedLine search using Ovid (Ovid Technologies, New York, New York) was performed. The database was searched from the most recent update available in mid-June 2000 back through 1991. Initial search terms were Tuberculosis/pc,ep,tm (Prevention & Control, Epidemiology, Transmission) AND Health facilities. The search was further limited to English-language articles. This yielded 257 references. Abstracts of these references were reviewed to choose appropriate articles. Additional Medline search strategies included Guidelines AND Tuberculosis/pc (which added 5 references not previously obtained), and (Tuberculosis OR Mycobacterium tuberculosis) AND Occupational exposure (which yielded 64 additional references, only 2 of which were useful). The author’s files served as another source of articles. Finally, potentially useful references found while reading the initial papers were also reviewed. Although the guidelines are generally applicable, because the expectation of implementation is primarily in U.S. hospitals, papers regarding health-care facilities outside of the United States were not included. Not all papers reviewed were included in the final document—papers were chosen either for the strength of their data or because they contributed a unique view into the implementation of the CDC standards.

IMPACT OF FOLLOWING THE GUIDELINES

Studies of Implementation of Entire Guidelines

Studies Showing Resolution of Outbreaks

The strongest evidence for the beneficial impact of the CDC guidelines comes from institutions where control measures were implemented

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

in response to nosocomial transmission of tuberculosis to patients and/or health care workers. Implementation of these measures then led to decreases in nosocomial cases of tuberculosis infection or disease.

Wenger and coworkers (13) reported the experience of Jackson Memorial Hospital, Miami, Florida, following an outbreak of MDR tuberculosis from 1988 to 1990 on an HIV ward (4, 14). Control measures were implemented over time, starting in March 1990. The measures implemented included the following:

March

  • Stricter enforcement of isolation policy to include isolation of any HIV-positive patient with an abnormal chest radiograph (CXR)

  • Change in criteria for stopping isolation from discontinuation after 7 days on therapy to discontinuation only after three negative smears for acid-fast bacilli (AFB) (or after reduction in AFB on three smears plus a clinical response)

  • Enforcement of policy to keep tuberculosis patients in their rooms unless medically necessary and having patients wear a surgical mask when out of their rooms

  • Sputum induction done only in isolation rooms

  • Initial therapy for tuberculosis with four drugs

April (through April 1991)

  • The 6 tuberculosis isolation rooms (of 23) without negative pressure were repaired, and the ventilation in the other rooms was made more consistent

June

  • Aerosolized pentamidine administered only in isolation room

September

  • Change from cup-type surgical mask to submicron mask for health care workers

A review of admissions of HIV-positive patients with MDR tuberculosis was performed, covering three time periods: initial period (January 1990 to May 1990), early follow-up (June 1990 to February 1991), and late follow-up (March 1991 to June 1992). There was a decrease in MDR tuberculosis patient-days over the three periods (222/100 real days initially, then 119/100, and finally 16/100). Fifteen patients with MDR tuberculosis were admitted during the initial period: 12 (80 percent) had been exposed while on the HIV ward. Eleven patients were admitted during the follow-up periods, only five of whom had been exposed on the ward, all during the initial period. No known patient exposures occurred during the follow-up periods.

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

Health care worker PPD test results were also reviewed over the same time periods. A total of 39 health care workers were previously PPD negative and tested (25 during the initial period, 17 during early follow-up, and 23 during the late follow-up). There was a total of 10 PPD conversions: 7/25 (28 percent) in the initial period, 3/17 (18 percent) in early follow-up, and 0/23 in late follow-up (P < 0.01). Of the three PPD conversions during the early follow-up period, two were linked to exposure to a patient with MDR tuberculosis who was not isolated on admission because of the fact that he was on therapy and had been AFB smear negative at the time of a recent hospital discharge. However, he subsequently proved to be smear positive. This led to an additional policy that any patient with a history of MDR tuberculosis would be isolated regardless of previous smear and treatment status.

The authors point out that it is difficult to know what components of the control measures were most important. However, the early implementation of administrative controls linked with beginning improvements in engineering controls led to a reduction in nosocomial transmission of MDR tuberculosis to other patients, as well as a reduction in PPD conversions in health care workers.

Similarly, Maloney and colleagues (15) detailed control methods implemented in June through October 1991 after an outbreak of MDR tuberculosis at Cabrini Medical Center in New York City. Control measures included improved isolation criteria (not detailed in the paper, but 90 percent of patients with MDR tuberculosis were isolated on admission, compared with isolation of 40 percent of patients preintervention) and molded surgical masks for employees (June): improved lab services (July); increase from 0/10 tuberculosis isolation rooms with negative pressure to 16/27 with negative pressure (September); and a chamber for sputum induction and pentamidine administration (October).

With the adoption of these measures the number of patients with MDR tuberculosis who had previously been admitted to Cabrini fell from 24 in the preintervention period (January 1990 through June 1991) to 6 in the postintervention period (July 1991 through August 1992). Three of the six postintervention patients also had documented nonhospital or preintervention exposures documented. In the postintervention period only 1 patient was found to have had a documented nosocomial exposure during a previous hospitalization, as opposed to 20/24 (83%) in the preintervention period.

Implementation of control measures led to no change in the overall rate of PPD conversions (~3 percent). However the rate of conversion on the HIV and medical wards fell from 16.7 percent during the preintervention period to 5.1 percent postintervention (p = 0.02), with no change on wards that did not usually house tuberculosis patients. The postintervention PPD

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

rates on HIV and medicine wards became essentially the same as the rates on other wards (5.1 percent versus 4.0 percent; p = 0.5).

Again, the impact of the individual control measures could not be determined, but clearly, the overall impact was significant. The authors note that the overall PPD conversion rate was unchanged. They highlight the importance of determining job-specific rates.

Blumberg and colleagues (16) reported the efforts made at Grady Memorial Hospital in Atlanta. These were in response to nosocomial transmissions of drug-sensitive tuberculosis in 1991 and early 1992 (5). Control measures implemented included the following:

March 1

  • Expanded isolation policy—all patients with known or suspected tuberculosis (including all patients for whom AFB smear and culture were ordered), also any patient with HIV infection (or risk for HIV infection with unknown serology) with abnormal CXR. Increased surveillance by infection control to ensure that patients for whom smears ordered were in isolation.

  • Isolation stopped only after three negative AFB smears (previously stopped after 2 weeks of therapy)

  • Increased physician education

  • Window fans added to 90 rooms to provide negative pressure

June 1

  • Submicron masks used for personal respiratory protection

July 1

  • PPD testing done every 6 months now included nonemployee health care workers (e.g., attendings, house staff, medical students)

  • tuberculosis nurse epidemiologist hired

To determine the effectiveness of these measures the authors reviewed tuberculosis exposure episodes (from July 1, 1991, to June 30, 1994) and PPD conversions (from January 1, 1992 to June 30, 1994). Over the 3-year period there were 752 admissions (673 patients) with tuberculosis; for 461 admissions (61 percent) the patients had positive AFB smears and were considered infectious. The results for these patients are shown in Table D-1.

Employee PPD conversion rates fell steadily from 3.3 percent to 0.4 percent during the postintervention period (for trend, p < 0.001). For the January-June 1994 PPD conversions (23/5,153 [0.4 percent]) no clustering by work area was noted. In fact only 10 health care workers had direct patient contact on wards where tuberculosis patients were housed, 4 had patient contact on low-risk tuberculosis areas (e.g., neonatal intensive care unit [ICU]), and 9 had no patient contact, suggesting that more than half of the conversions may have been community acquired.

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

Tuberculosis isolation rooms were tested with smoke approximately every 3 months. The failure rate ranged from 6.1 percent to 21.7 percent (mean, 16.5 percent). One room tested with sulfur hexafluoride had 4.9 ACH. The author suggest that their data imply that the improvements in PPD conversion rates were primarily the result of improved administrative controls since changes mirrored improved isolation as a result of the new policies. They argue that since room negative pressure was demonstrated to be frequently suboptimal, engineering controls were not the major factor in the improvements. Likewise submicron masks appeared to be adequate. The new policies resulted in only one of eight patients placed on tuberculosis isolation having culture-confirmed tuberculosis.

Columbia-Presbyterian Medical Center in New York City had control measures detailed by Bangsberg and colleagues (17). They revised their tuberculosis control guidelines to be consistent with the CDC guidelines. Prior to June, 1992, medical house staff were PPD tested at baseline and were then instructed to be tested annually by their primary physicians. Starting in June 1992, PPD testing was done every 6 months on medical house staff. The overall rate of participation was 92 percent.

Revised tuberculosis control measures included stricter isolation policy (implemented in May 1992) so that patients with HIV infection or HIV in fection risk factors or who were homeless and presented with pneumonia or evidence of tuberculosis were placed in tuberculosis isolation until three sputum samples were AFB negative and the patient was judged noninfectious by pulmonary and infectious disease consultants. Tuberculosis isolation rooms were installed in the emergency department (ED) in July 1992. A tuberculosis service was implemented at the end of June 1993. In July 1993 3M respirators (type not stated) were instituted.

TABLE D-1. Results of Interventions at Grady Memorial Hospital

Measure

Pre-intervention (7/91–2/92)

Post-intervention (3/92–6/94)

p

No. of tuberculosis admissions

184

568

No. of tuberculosis admissions/ month (AFB +)

23 (12.9)

20 (12.8)

No. of exposure episodes/month

4.4

0.6

No. of exposure days/month

35.4

3.3

< 0.001

No. of patients not appropriately isolated/total no. of patients

35/103 (34%)

18/358 (5%)

< 0.001

No. of HIV infected patients admissions associated with exposure episodes/total no. of admissions

22/33 (67%)

7/143 (5%)

< 0.001

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

The number of patients with pulmonary tuberculosis appropriately isolated during January through June 1992 (preintervention) was only 29/71 (38 percent). This increased to 29/45 (64 percent) from January to December 1992. Subsequent isolation rates continued to improve slightly: 60/82 (72 percent) from January to June 1993 and 33/44 (75 percent) from July to December 1993 (p < 0.01 for trend). Results considering only HIV infected patients were similar.

PPD conversion rates among house staff were as follows: June 1992, 10 percent (5.8/100 person-years); December 1992, 3 percent (5.1/100 person-years); June 1993, 0 percent; December 1993, 1 percent (2.3/100 person-years); June 1994, 0 percent. Conversion rates were calculated per 100 person-years of exposure because of varying exposure times possible at the June 1992 testing (12–36 months, depending on the year of the resident).

Because the biggest drop occurred between December 1992 and June 1993, the authors imply that isolation policy and possibly the tuberculosis isolation rooms in the ED were most important in leading to the improvements. Clearly their expanded isolation policy resulted in much better isolation of patients with pulmonary tuberculosis over this time period.

Stroud and colleagues (18) reviewed the effects of control measures at Roosevelt during three 15-month periods: period I, January 1989 to March 1990; period II, April 1990 to June 1991; and period III, July 1991 to September 1992. Period I was essentially a preintervention period, during which there was an outbreak of nosocomial tuberculosis (7). Patients with suspected tuberculosis were admitted to private room (only 1 of 16 with negative pressure), doors were often left open, and isolation was discontinued without negative AFB smears. Surgical masks were used for respiratory protection. Most rooms, however, did exhaust to the outside.

During period II administrative controls were enforced—a lower threshold for initiating isolation was set, more aggressive evaluation for possible tuberculosis was started, and more aggressive treatment regimens were started if there was no response to initial therapy. An effort was made to keep HIV-infected patients off wards with tuberculosis patients.

In period III engineering controls were phased in. From July to December 1991, 11 rooms were fitted with UVGI. From November 1991 through January 1992 seven of these rooms were fitted with exhaust fans for ≥6 ACH and negative pressure. Isolation chambers were used for sputum induction/aerosolized pentamidine administration. Surgical masks (Technol 47080070) were used through all three study periods. With the implementation of administrative controls during periods II and III, patients with pulmonary tuberculosis were more likely to be isolated on admission (44 percent versus 0 percent during period I). The median delay before isolation initiated (2 versus 6 days) also improved.

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

During period I, the likelihood of an HIV-infected patient getting tuberculosis decreased with distance from source patient room (but oddly, not related to the amount of time spent on the ward). Smear negative patients were not a source of nosocomial infection in period I. Crude rates of nosocomial tuberculosis were reduced from 8.8 percent during period I to 2.6 percent during period II and to 0 percent in period III. During period II, there was no association of nosocomial tuberculosis with distance from the source patient’s room.

The impact on health care worker PPD conversion rates could not be determined due to insufficient data. However, during period II plus period III, PPD conversion rates were higher on tuberculosis wards than on other wards (5/29 versus 0/15; p = 0.15).

The impact of implementing the CDC guidelines on employee PPD conversion rates at St. Clare’s Hospital in New York was reported by Fella and colleagues (19). Beginning in 1991, all health care workers with patient contact had PPD testing every 6 months; others were tested annually. Two-step testing of new employees was implemented in February 1993. Prior to 1991, no negative-pressure isolation rooms were available at St. Clare’s. The implementation of control measures and PPD conversion rates are shown in Table D-2.

In an abstract presented at the 1994 Annual Conference of the Society for Occupational and Environmental Health—Tuberculosis Control in the Workplace: Science, Implementation, and Prevention Policy, Koll and colleagues (20) summarized data from Beth Israel Medical Center (BIMC) in New York City. The hospital had large numbers of tuberculosis patients and admissions in the early 1990s. A comprehensive tuberculosis policy (based on the 1990 CDC guidelines) was implemented in mid-1992. tuberculosis isolation rooms with negative pressure, ≥6 ACH, and UVGI were

TABLE D-2. PPD Conversions and Interventions at St. Clare’s Hospital

Year

Interval

No. PPD Positive/ No. tested

Rate (%)

PRP

Environmental Interventions

1991

Jan–June

30/145

20.7

Technol shield

Negative-pressure rooms

July–Dec

11/158

7.0

Technol shield

1992

Jan–June

7/219

3.2

Particulate respirator UVGI

July–Dec

14/227

6.2

Particulate respirator

1993

Jan–June

10/249

4.0

Dust-mist-fume respirator

July–Dec

9/154

5.8

Dust-mist-fume respirator

NOTE: PRP = personal respiratory protection.

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

made available. Automatic door closers were installed. HEPA filters were used for recirculated air. A protocol for rapid identification of patients with possible tuberculosis was instituted. Surgical masks were replaced with submicron masks. Strict adherence to tuberculosis isolation precautions was promoted with patient education and incentives. Booths were used for aerosolized pentamidine administration and sputum induction. An annual PPD program for health care workers was implemented, with testing of high-risk health care workers every six months. The impact of the policies on health care worker PPD conversion is noted in Table D-3.

The reason for such small numbers of respiratory therapist conversions was not noted in the abstract. The authors noted that the rate of compliance with PPD testing in 1991 and 1992 was <75 percent; in 1993 it was 95 percent, so the reduction may have been even greater than documented. Unfortunately, rates are not provided, but overall the data are suggestive.

Grant (21) presented the results of a review of all tuberculosis cases at Parkland Memorial Hospital, Dallas, in 1994 and 1995. A variety of enhancements to the tuberculosis control policies were made from April to December 1994, including certification of PPD placement, an algorithm for tuberculosis isolation room assignment in times of low availability, standing orders for patients with suspected tuberculosis, increased UV in waiting areas, a fit testing program, increased employee PPD frequency (depending on job category), and notification of infection control by radiology of suspicious CXRs. Previously, an increase in health care worker PPD conversions had led to improvements in engineering controls, with 64 tuberculosis isolation rooms being made available.

Over the 2 years, 253 tuberculosis patients were admitted, 85 percent of whom had pulmonary disease. In 1994, all AFB smears were processed within 24 hours. Nontuberculous mycobacteria (NTM) were found in 193/ 407 (47 percent) patients with a positive AFB smear. Further results are presented in Table D-4.

The authors report that the data gathered each year were released along with information about the importance of compliance with the tuberculosis control protocols. They suggest that the high rate of NTM made the diagnosis of true tuberculosis more difficult. They also suggest that

TABLE D-3. PPD Conversions in Health Care Workers at BIMC

 

No. of Conversions

Year

House Staff

Nurses

RT

All Other

1991

9

14

0

7

1992

4

9

0

7

1993

1

7

0

6

 

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

TABLE D-4. Results of Tuberculosis Control Measures at Parkland Memorial Hospital

Percent

Measure

1994

1995

p

Patient isolated on admission day

87

79

Patient isolated by 2nd hospital day

89

83

Patient isolated within 72 hours

91

86

Patient never isolated

4.1

7.5

Employee tuberculosis exposure rate

18

25

0.03

Health care worker compliance with PPD testing

49

74

PPD conversions

2.7

3.5

interpretation of apparent increased PPD conversion rates may be spurious because some employees not tested in 1994 may already have had positive PPD test results and would not have been counted as conversions in 1995.

This paper highlights the fact that despite implementation of a protocol and other measures, reductions in employee skin test conversions is not inevitable. Clearly, Parkland suffered from continued delayed isolation of patients and even an increase in employee exposures. This occurred despite an apparently energetic infection control program.

Very little is known about tuberculosis control in nonhospital settings. Nolan and colleagues (22) reported on the control of an outbreak in a shelter for homeless men in Seattle. During December 1986 and January 1987, seven cases of tuberculosis were diagnosed in shelter clients. This prompted mass PPD testing of all the residents of the shelter. Anyone with a positive PPD test result (≥5 millimeter) or symptoms suggestive of tuberculosis were offered chest radiographs. This resulted in the identification of six additional asymptomatic cases of tubreculosis. Persons with tuberculosis were excluded from the shelter, and isoniazid (INH) therapy for latent tuberculosis infection was offered to everyone with a positive PPD test result. The air-handling system (which provided minimal air changes—air was recirculated for economy of heating) was reengineered. Thirty-six UVGI lights were installed in the duct system. The intensity-time dosage was considered adequate to kill 95 percent of the Mycobacterium tuberculosis organisms exposed to it. These interventions led to an interruption of the outbreak. Only five residents were found to have active tuberculosis over the next 2 years. Although this shelter did not follow the CDC guidelines in the strictest sense, their control plan included implementation of administrative controls (identification of cases with subsequent isolation [i.e., removal from the shelter]) and engineering controls. Provision of therapy for latent tuberculosis infection (LTBI) was likely also an important aspect in preventing further cases of active disease in those already infected.

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×
Studies Correlating Implementation and Outcomes

Although not as compelling as a directed study of the impact of control measures, studies correlating implementation of control measures with relevant outcomes can also provide insight into the efficacy of the CDC guidelines.

One such example is from a Society for Healthcare Epidemiology of America (SHEA)-CDC survey of 1989–1992 tuberculosis control practices reported by Fridkin and colleagues (23, 24). The survey was sent to all members of SHEA in March 1993. Members from 210 hospitals responded. Part II of the results (24) focused on the efficacy of control measures. It showed that “high-risk” employees (e.g., respiratory therapists and bronchoscopists) were more likely than other health care workers to have PPD conversion if ≥6 tuberculosis patients per year admitted, if the hospital was “large” (≥437 beds), or if MDR tuberculosis was present. The most significant impact on both high risk and other PPD conversions was whether the hospital admitted ≥6 tuberculosis patients (for non-high risk health care workers, PPD conversions of 1.2 percent in high-volume hospital versus 0.6 percent in low-volume hospitals; for high-risk health care workers, PPD conversion rates were 1.9 percent versus 0.2 percent).

The authors evaluated four criteria from the 1990 CDC guidelines: (a) placing known/suspected tuberculosis patients into single patient room (or cohorting), (b) negative-pressure ventilation, (c) air exhaust directly to outside, and (d) ≥6 ACH. Hospitals with ≥ tuberculosis patients meeting all four criteria had PPD conversion rates of 0.60 percent, whereas they were 1.89 percent for hospitals that did not (p = 0.02). Hospitals meeting at least criteria a to c had PPD conversion rates of 0.62 percent whereas the rate was 1.83 percent for those that did not (p = 0.03). The data suggested that having negative pressure or outside exhaust versus not having one or the other also reduced rates, but this did not reach statistical significance. The use of a submicron mask versus a surgical mask made no difference in conversion rates. For hospitals with less than six tuberculosis admissions per year, no difference in PPD conversion rates could be shown to be related to control measures.

A similar survey on tuberculosis control measures was sent to members of the Association for Professionals in Infection Control and Epidemiology (APIC) in March 1993, as reported by Sinkowitz and colleagues (25). It also covered practices from 1989 to 1992. Data were obtained from 1,494 hospitals. Compared with the SHEA-CDC survey, the hospitals in this APIC survey were more likely to be a community hospital and more likely to not have any tuberculosis admissions in 1992. Results of the survey are summarized in Table D-5.

Whether or not tuberculosis isolation rooms met CDC criteria was also reviewed, but the data are not summarized here.

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

TABLE D-5. Results of CDC-APIC Tuberculosis Control Survey

Percent

Measure

1989

1990

1991

1992

Hospital admitted patient with tuberculosis

46.4

49.6

53.0

56.6

PPD conversion rate (pooled average)

0.39

0.42

0.47

0.51

Respiratory protection provided

Surgical mask

96.8

95.8

91.3

66.8

Submicron mask

2.5

3.4

6.8

19.0

Dust-mist respirator

0.3

0.5

1.1

10.9

Dust-mist-fume respirator

0

0

0.3

2.4

HEPA respirator

0

0

0.2

0.5

Slightly different than in the SHEA-CDC study, bronchoscopists at hospitals with one to five tuberculosis patients per year were more likely than other health care workers to convert their PPD test results. This was not true for hospitals with ≥6 tuberculosis patients per year. Like the CDC-SHEA survey, the type of respiratory protection in use did not correlate with PPD conversion rates. However, unlike the CDC-SHEA survey, PPD conversion rates at hospitals were not related to control measures.

A result similar to that of the APIC result was found in a review of tuberculosis control measures in the 13 hospitals of a midwestern health system, as reviewed by Woeltje and colleagues (26). This survey was performed in 1994–1995. All hospitals had a tuberculosis plan, and all had annual testing of at least selected employees as recommended by the guidelines. Six of 13 (46 percent) of the hospitals were considered very low risk, 6 (46 percent) were considered low risk, and 1 (6 percent) was considered intermediate risk.

Tuberculosis isolation rooms were available at 10/13 (77%) of hospitals; however, only 44 to 100 percent of rooms (median, 88 percent) actually had negative pressure. Dust-mist-fume respirators were used most commonly. PPD conversion rates in 1994 ranged from 0 to 1.0 percent (median, 0.3 percent). The hospital location (urban/rural), type of respiratory protection, tuberculosis risk category, number of tuberculosis isolation rooms, percentage of tuberculosis isolation rooms that were actually at negative pressure, and number of tuberculosis cases were not correlated with PPD conversion. Only the tuberculosis case rate approached significance (p = 0.06, but this may have been spurious, as noted in the discussion section of this paper). In the discussion the authors note that actual compliance with CDC guidelines fell short of the hospitals’ written policies.

Studies Showing Stable Control

Although not as compelling as studies showing the before-and-after effects of implementing control measures, the experiences of hospitals

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

(especially those with large numbers of tuberculosis patients) that have low nosocomial tuberculosis rates and health care worker PPD conversion rates by following the CDC guidelines provide further assurance of the effectiveness of the guidelines.

An extremely detailed search for possible cases of nosocomial transmission of tuberculosis was done at Cook County Hospital in Chicago, where French and colleagues performed DNA fingerprinting on one isolate from every patient with tuberculosis for 1 year, from April 1995 through March 1996 (27). A comprehensive record review of patients whose isolates were in a fingerprint cluster was done to determine chance of cross-transmission. Overall, 91/168 (54 percent) isolates were in 15 clusters. There were six clusters of 2 isolates, 7 clusters of 3 to 8 isolates each, one cluster of 16 isolates, and one cluster of 29 isolates. The risk factors for clustering were birth in United States, male sex, African-American ethnicity, alcohol or illicit drug abuse, and homelessness. On multivariate analysis, only male sex and birth in the United States were associated with clustering.

For 13 of 15 clusters (46 patients), no instances were identified where two patients were inpatients or outpatients at same time. For the two largest clusters, 148 instances of two patients being on hospital grounds at same time were found. For 144/148 instances, cross-transmission was thought to be unlikely because of different sensitivity patterns (32 instances) or lack of geographic overlap of patients (112 instances). Of four remaining instances, the site of possible cross-transmission was ED (3 instances), and the HIV clinic (1 instance). In one case the possible source patient had only extrapulmonary tuberculosis, so nosocomial transmission was thought to be unlikely. In another case, only 5 weeks elapsed from the time of exposure to the diagnosis of fibrotic pulmonary disease in an immunocompetent patient. Cross-transmission in this case was thought to be implausible.

Of two remaining instances, the same source patient was involved. In one instance the source patient (patient A, HIV positive, CD4 count of 423 cells per milliliter) had a CXR consistent with miliary tuberculosis. The patient was masked and placed in isolation within 1.25 hours of admission. Patient B (also HIV positive) was brought to the ED by ambulance after patient A had been placed in isolation. Patient B had a history of a positive PPD test result and so was masked and placed in an isolation room 50 yards from patient A. Eight months later patient B developed pulmonary tuberculosis. Given the prompt masking and isolation of both patients and a history of a positive PPD, nosocomial transmission to patient B was thought to be unlikely (albeit possible, since droplet nuclei can stay suspended for some time).

The last possible patient exposure occurred in the HIV clinic. Patient C (also HIV positive) was in a clinic concurrent with patient A 5 weeks

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
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before patient A was diagnosed. Patient A had complained of low-grade fevers and weight loss, but a lack of cough and pulmonary signs was specifically documented. Four months later patient C developed pulmonary tuberculosis caused by an isolate with the same fingerprint as that of the isolate from patient A. Despite a documented lack of pulmonary symptoms, nosocomial transmission was thought to be possible.

During the study period eight patients with pulmonary tuberculosis were not isolated before the diagnosis was made. Two had isolates in clusters: six did not. A total of 186 employees had follow-up testing with no PPD conversions. In fact, 28 of 70 (40 percent) health care workers with PPD conversions over the entire study period had no adult patient care responsibilities.

The authors state that their hospital follows guidelines consistent with the CDC guidelines, although details are not provided. This paper suggests that even in a hospital with a large number of tuberculosis admissions, the CDC guidelines are effective at preventing nosocomial transmission. Of the two possible cases of nosocomial transmission, no breakdown in following the guidelines occurred. This points out that unless every patient is isolated for every visit, some nosocomial transmission of tuberculosis may be unavoidable.

Jernigan and colleagues (28) reported on a retrospective questionnaire that was sent to 52 former residents who had done a total of 70 6-week (420 physician-weeks) rotations at a tuberculosis sanatorium affiliated with the University of Virginia. There were 10 unprotected exposures to tuberculosis patients during training reported by the former house staff, 2 of which occurred at the sanatorium. No PPD conversions were reported during residency. The sanatorium had tuberculosis isolation rooms with negative pressure as well as UVGI (details were not given), and only simple surgical masks were used at the facility. Since “administrative controls” are somewhat built in at a sanatorium (in that tuberculosis is presumably known in all patients prior to their arrival), this suggests that even in a potentially high-risk environment, routine engineering controls and simple personal respiratory protection are adequate.

Studies of Specific Aspects of the Guidelines

Administrative Controls

The major role of administrative controls is to ensure that patients with pulmonary tuberculosis are promptly isolated. In most settings this requires isolating many patients who prove not to have tuberculosis for every patient who actually does have tuberculosis. As pointed out in the CDC guidelines, criteria for isolation must be derived locally, taking into

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

account the local prevalence and presentations of tuberculosis. Many different isolation strategies have been reported.

Pegues and colleagues (29) studied the impact at the Massachusetts General Hospital from 1993 through 1994 after the implementation in 1993 of a tuberculosis isolation algorithm. The algorithm includes typical signs and symptoms (chronic cough, fever, weight loss, etc.) and risk factors (HIV infection, homeless, intravenous drug abuse [IVDA], jail, immigration from a country where tuberculosis is endemic, etc.), as well as the CXR. If the patient had a normal CXR, then the patient was not placed in isolation. If the CXR was abnormal, then a risk evaluation was done. If low risk, the patient was placed in a private room until one smear was AFB negative. If the patient was at moderate risk (i.e., had risk factors or a suspicious CXR), the likely degree of infectivity was considered. If the patient was judged to be likely infectious (as determined by the presence of a cavity on CXR or cough/sputum production by history), then the patient was placed in a tuberculosis isolation room. Otherwise the patient was placed in a lesser isolation room until three sputum samples were shown to be AFB negative.

There were 31 case patients with pulmonary tuberculosis over the 2-year study period (out of 58 patients with + AFB smears). All had an abnormal CXR, and 9/31 (29 percent) had cavitary disease. Ages ranged from 7 months to 97 years.

Isolation was initiated within 24 hours of admission in 19/31 (61 percent), 17 in the ED. Of 12 patients not isolated appropriately, 7 were eventually isolated (after 2 to 31 days; median, 9 days), and 5 were never isolated during admission (range, 3 to 28 days; median, 4 days). Reasons for inappropriately not isolating the patients included misclassified risk factors for five patients (three with HIV infection); seven patients had atypical or misinterpreted (but abnormal) CXRs and were not captured by the algorithm because they had no risk factors. No data on the total number of patients isolated are presented.

The 12 patients inappropriately not isolated led to 136 patient-exposure days. Of 11 roommates and 281 employees exposed, no PPD conversions or cases of active tuberculosis were found.

In the discussion the authors note that if the five patients who should have been isolated by the algorithm had been isolated, the sensitivity would be 77 percent. Inclusion of other risk factors (such as end-stage renal disease and residence at a long-term-care facility) would have improved the sensitivity, but at the cost of much more overisolation. Unfortunately, there is no discussion as to whether the new algorithm led to improvements in isolation practices compared with the previous policies.

The results of a survey including isolation practices in 159 Veterans Affairs hospitals (100% response, but not on all questions) were reported by Roy (30). Overall, 1,063 patients/month were isolated (median, 3 per

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

facility). In 1993, a total of 974 patients were diagnosed with pulmonary tuberculosis (median, 3 per facility). The ratio of patients isolated/patients with pulmonary tuberculosis ranged from 1 to 120 (median, 12). There was no correlation between this ratio and the number of tuberculosis patients at the facility. Unfortunately there are no data presented on health care worker PPD conversion rates. Nevertheless, the variability in the degree of overisolation is striking. The methods used to determine who should be isolated were not discussed.

Columbia University has a renowned medical informatics group, and not surprisingly, an informatics approach to tuberculosis isolation was evaluated there, as reported by Knirsch and colleagues (31).

A clinical protocol for tuberculosis isolation was implemented in 1992 (17). Tuberculosis isolation was to be initiated (and continued until three negative AFB smears were obtained) in patients with a CXR suggesting tuberculosis (e.g., cavitary lesion, or any abnormality on CXR for patients with HIV infection) plus HIV risk factors or homelessness. Overall prompt isolation of tuberculosis patients improved from 51 percent in 1992 to 75 percent in 1993.

An automated protocol of computer screening of records was developed in 1995 using the CXR as the starting point. CXR reports were already automatically parsed at Columbia, so terms suggesting tuberculosis could be checked for. If the CXR was abnormal, immunodeficiency status was checked from other records (e.g., laboratory and pharmacy records). The hospital epidemiologist was notified via a computer generated e-mail to review the record for anyone meeting the preselected criteria. In 1995–1996 the combined clinical and automated protocol correctly isolated 34/43 (79 percent) of patients with tuberculosis. The clinical system alone would have isolated 30/43 (70 percent). The automated alert system flagged the records of 22/43 patients (51 percent). The automated protocol generated 15 alerts for every culture-positive tuberculosis patient, which was thought to be a tolerable number. By its nature, the system failed to detect patients with a normal CXR and patients with an abnormal CXR but no evidence of HIV infection—these accounted for most of the 21 percent not isolated by either system.

An effort to improve the isolation protocol at Grady was reported by Bock and colleagues (32). The charts of 376 patients (12 percent of all medicine admissions) on tuberculosis isolation from October through December 1993 were reviewed shortly after admission. Of these, 53 had pulmonary tuberculosis and 51 (96 percent) had been appropriately isolated. The two patients missed should have been isolated under existing protocols. Thus, 7.4 patients were isolated for every case of tuberculosis (positive predictive value, 14 percent).

A total of 295 of these patients (42 with tuberculosis) agreed to be interviewed. The authors evaluated 15 variables available on admission.

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

On univariate analysis, the presence of a cavity or upper lobe infiltrate was most predictive of tuberculosis. On multivariate analysis those factors remained significant, and a history of knowing someone with tuberculosis and a self-report of a previous positive PPD test result were also predictive. A self-report of INH preventative therapy in the past was protective. When stratified by HIV infection status, for patients without HIV infection, only radiological finding were significant, whereas in patients with HIV infection the radiological findings were not predictive.

A model was made including CXR findings, history of a positive PPD test result without INH therapy, and a history of knowing someone with tuberculosis. If this model were applied to the patient data set, only 129 of 295 patients would have been placed on isolation (a 56 percent reduction), including 34 of 42 patients with tuberculosis (overisolation factor, 3.8). Of the eight patients who would not have been isolated, four were smear positive. The hypothetical policy had a sensitivity of 81 percent, and a positive predictive value of 26 percent. The authors concluded that since the policy was supposed to prevent nosocomial transmission of tuberculosis, the hypothetical policy was not acceptable because of its lower sensitivity.

The impact of a tuberculosis team on appropriate isolation was noted by Fazal and colleagues (33). In April 1993, a tuberculosis team was started at the Bronx-Lebanon Hospital, New York. At the same time an isolation algorithm was implemented, so that patients with suspected tuberculosis would promptly be placed in isolation and AFB sputum would be obtained. The team consisted of infectious disease physician, an internist, and a physician’s assistant. Daily rounds were conducted, and a team member was available 24 hours/day for questions. The time to appropriate isolation of tuberculosis patients was evaluated from September 1992 through October 1993 (7 months each pre- and postteam). Results of the team approach are shown in Table D-6.

No differences in demographics or number with MDR tuberculosis were noted. The degree of “overisolation” was not discussed, but the discussion does comment that isolation rooms were more readily available postteam due to more appropriate use. Length of stay decreased due to more timely smears and improved discharge planning (weekly rounds with community tuberculosis clinic staff). Despite the improvements, failure to isolate all AFB+ patients on admission was still a problem. Their guidelines were to undergo further evaluation and refinement.

Decreasing the delays in “ruling out” tuberculosis was also the focus of a study by Harmon and Roche (34) at a Hartford, Connecticut, hospital. Initial data were gathered on 52 patients on tuberculosis isolation over a 2-month period. A total of 36/52 (69 percent) were on tuberculosis precautions on the day of admission, and 43/52 (83 percent) were on tuberculosis isolation within 24 hours of admission. Only 33 had tuberculosis

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

TABLE D-6. Effects of Forming a Tuberculosis Team on Patient Isolation Practices

Measure

Preteam

Postteam

p

No. of AFB+ tuberculosis patients admitted

46

39

No. (%) of AFB+ patients isolated within 24 hours

16 (35)

23 (59)

0.03

Mean no. of days patients not isolated

19.0

3.5

0.002

Median no. of days patients not isolated

12

0

No. (%) of patients never isolated

19 (41)

2 (5)

ruled out with three negative smears—this took a mean 6.6 days (range, 3 to 13). Continuous quality improvement (CQI) methods were used to design a protocol to improve the process of ruling out tuberculosis. Postintervention, 28 patients were evaluated on protocol. Fifteen (54 percent) were ruled out within 4 days, the target goal. Mean time to stopping isolation was 4.9 days (range, 3 to 19 days, p 0.001). No data were presented on how many patients were actually ruled in. Because a historical comparison group was used, the reduction in evaluation may have been due to the increased attention to tuberculosis, not the protocol per se. Nevertheless, their efforts succeeded in reducing the delays associated with ruling out tuberculosis.

Some hospitals have taken a very broad policy in isolating patients to rule out tuberculosis. An increase in health care worker PPD conversion from 0.3 to 1.7 percent between January and June 1991 at the University of Louisville Hospital was attributed to a failure to follow 1990 CDC guidelines (35). This led to the mandatory isolation of all patients presenting with community-acquired pneumonia (until two AFB smears were negative, or until tuberculosis was “ruled out on clinical grounds”). This policy was started in July 1991. Uyamadu and colleagues (36) reported that from July 1991 through December 1994, 70 patients with pulmonary tuberculosis were admitted, 33 (47 percent) of whom were AFB positive. All but one (who presented with mental status changes) were isolated on admission. The health care worker PPD conversion rate fell to an average of 0.6 percent (range, 0.3 to 0.8 percent per 6-month follow-up period).

No clear discussion of how much overisolation occurred. The authors state that “25 percent of patients being isolated will not meet CDC criteria for high risk for tuberculosis.” This suggests that 75 percent would meet criteria for risk and so would have had to be isolated anyway. But this still does not address how many patients without tuberculosis were isolated for every patient with tuberculosis. Still, this paper suggests that aggressive isolation will reduce employee tuberculosis infection rates, as marked by a reduction in the PPD conversion rates.

Additional model algorithms for determining the need for isolation have been reported by Trovillion and colleagues (37) from Barnes-Jewish

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

Hospital in St. Louis, El-Solh and colleagues (38) from Eire County Medical Center (affiliated with the State University of New York at Buffalo), and Redd and Susser (39) from the ED at Columbia in New York City. These algorithms encompass various risk factors available from history, as well as CXR results. They are all somewhat similar. The studies by El-Solh and colleagues and by Redd and Susser evaluate the potential utility of the algorithms. Data on actual implementation are lacking, however.

Engineering Controls

General/Ventilation

Most studies evaluating control methods have been in settings where multiple changes in control measures have occurred at once, so attributing results to just ventilation is difficult. Behrman and Shofer (40) reported on the ED of the University of Pennsylvania in Philadelphia. Baseline PPD results of ED staff and other hospital employees were similar. Attending physicians were not included because non-ED data were not complete. On a 1-year follow-up, health care workers in the ED had 6/50 (12 percent) conversions, versus 51/2,514 (2 percent) conversions for other health care workers.

A new ED facility with four tuberculosis isolation rooms, improved air flow throughout the ED, and Plexiglas shields and laminar air flow for registrars was opened in January of the third testing (2-year follow-up) period. With the implementation of these measures, PPD conversions were 0/64 for ED health care workers versus 36/3,000 (1.2 percent) for other health care workers. The authors noted that the numbers of tuberculosis patients seen in the ED did not decline over the study period. They also noted that their protocols (early triage, use of approved respirators) did not change during periods. The authors conclude that the drop in the PPD conversion rate was due to improved engineering controls, which were primarily changes in ventilation.

Ultraviolet Germicidal Irradiation

Since UVGI is mentioned only as a supplemental means of engineering control of tuberculosis, there are few new data on its use or effectiveness alone. Stead and colleagues (41) reported that tuberculosis isolation rooms at the University of Arkansas hospital had 15 ACH and UVGI. The use of masks was optional (the paper does not state whether actual use was common or not). There were 16 patients with tuberculosis in 1992, including a man with cavitary MDR tuberculosis disease whose case was presented as a case report at the beginning of the article. The annual PPD conversion rate was 0.7 percent overall. Only 1/137 employees exposed

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

to the case patient converted his PPD (and he was exposed while the patient was in the ICU on a ventilator, with negative AFB smears at the time). The report of Stead and colleagues implies that it was UVGI that was responsible for low PPD conversion rate, even though they had terrific ventilation. He cites one reference (42) regarding PPD conversion, despite 11 ACH in support of this. He also cites older data (43) on UVGI being effective even if no negative-pressure ventilation is available.

The paper by Jernigan et al. (28) cited previously included an interesting statement regarding National Jewish Hospital in Denver. A “personal communication” from L.J.Burton is cited stating that only two PPD conversions had occurred at National Jewish Hospital over a 10-year period, both associated with failure of an ultraviolet light system on a ward. I could not find a publication to confirm this.

Several recent reviews by Nardell (44), Macher (45), and Riley (46) present information on older studies on the efficacy of UVGI.

PROGRESS IN ADOPTION OF THE GUIDELINES

Degree of Implementation

General

Initial studies early in the 1990s suggested poor initial implementation of the 1990 CDC guidelines. Manangan and colleagues (47) reported on a 1992 survey of 180 Texas hospitals (of 475 in the state, of which 151 [83 percent] responded). In 1991, 122/151 (81 percent) had at least 1 tuberculosis admission (up from 98/151 [65 percent] in 1989). Overall, tuberculosis isolation rooms of any sort were not available at 25/140 (18 percent). Seventy-two percent of hospitals had at least one room meeting all CDC criteria. Of the hospitals that had tuberculosis isolation rooms, the rooms had negative pressure in 108/133 (81 percent), ≥6 ACH in 97/131 (74 percent), and air directly vented to outside in 109/131 (83 percent). Only 53/121 (44 percent) hospitals routinely checked the negative pressure in the tuberculosis isolation rooms. The rooms had a private bathroom in 125/134 (93 percent) hospitals. At 94/143 (66 percent) the door was kept closed at all times. Eighty-two percent of hospitals had only surgical masks available for health care workers. Ninety-seven percent performed baseline PPD testing, but only 91 percent performed PPD testing after an exposure.

Van Drunen (48) and colleagues presented data from a Minnesota survey of 17 hospitals carried out by APIC for 1989–1991. Overall there was a wide variety of practice. A total of 13/17 (76 percent) had tuberculosis isolation rooms available. Only three hospitals performed annual PPD tests; many hospitals let employees self-read the PPD test results. All

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

of the hospitals used surgical masks for personal respiratory protection. There were a total of 33 exposure events involving 1,031 health care workers (445 patient days). However, the rate of PPD conversion following exposure was only 0.97 percent. Although the authors indicate that their data show that practices in Minnesota hospitals were “reasonably consistent with critical elements of the 1990 CDC guidelines” full compliance was apparently uncommon.

McDiarmid and colleagues (49) reported on the results of OSHA inspections performed from May 1992 through October 1994. An OSHA database of reports (for 262/272 cases) as well as supplemental questionnaires completed by OSHA compliance officers (for 149/272 cases) were reviewed.

In May 1992 OSHA region II (New York, New Jersey, Puerto Rico, Virgin Islands) developed enforcement guidelines based on the CDC 1990 guidelines. In the fall of 1993 OSHA issued national guidelines (50). A total of 272 facilities were inspected by OSHA; of these 53 percent were in New York and New Jersey. Hospitals made up 45 percent of inspected facilities, nursing homes made up 17 percent, prisons made up 13 percent, shelters made up 5 percent, and other made up 20 percent (e.g., outpatient drug treatment centers, physician offices, Emergency Medical Services). Complaints of employees/unions prompted 71 percent of the inspections.

Overall 66/117 (56 percent) had a tuberculosis control program, and 77/97 (79 percent) screened patients/clients for tuberculosis on admission. A total of 60/117 (51 percent) had some form of tuberculosis isolation available, and 54/129 (42 percent) had negative-pressure isolation rooms. “Adequate” personal protective equipment was provided at 33/ 114 (29 percent) (surgical masks were provided at 21 percent of facilities, dust-mist respirators were provided at 38 percent, and no masks were provided at 14 percent). Seventy-nine percent performed at least annual PPDs. Overall hospitals had better compliance.

Only 54/101 facilities (53 percent) appropriately recorded positive PPD test results on the OSHA 2000 log. Following exposure incidents, facilities applied an average of 79 (standard deviation [SD] = 179) PPDs, finding mean of 0.75 (SD—1.5) converters, with 0.20 (SD—0.9) active cases of tuberculosis found among converters.

Forty-two percent of facilities received citations under the general-duty clause; 39 percent were cited for noncompliance with respiratory protection standard; 20 percent were cited for noncompliance with the recording and reporting standard. OSHA also requires room placarding— 10 percent of facilities were cited in violation of this.

The authors note a high degree of noncompliance during the study period; however, since most inspections were instigated by complaints, the selection of facilities may have been biased toward those with poorer

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

compliance. Also, the time distribution of surveys was not noted. Thus, low compliance may also reflect a lag time in planning and implementing a comprehensive program, especially if many surveys were at the early end of the survey period.

Although these initial studies suggested poor initial implementation of the guidelines, with time implementation overall seems to have improved. Part I of the 1993 SHEA-CDC survey reported by Fridkin et al. (23) covered the status of tuberculosis control practices from 1989 to 1992. The results were as follows. Members from 210 (out of 359 possible) hospitals responded to the survey.

Tuberculosis isolation rooms meeting all CDC criteria were available at 113/181 (62 percent) hospitals. A total of 205/205 (100 percent) placed suspected tuberculosis patients in private rooms, 138/181 (76 percent) had negative pressure, 140/181 (77 percent) had air exhaust directly to the outside, and 158/189 (84 percent) reported ≥6 ACH. UVGI was used in 14/196 (7 percent). Employee PPD testing at 199 reporting hospitals was done annually at 127 (64 percent), every 6 months at 10 (5 percent), every 2 years at 13 (7 percent), and at varied times depending on risk at 48 (24 percent). Personal respiratory protection provided varied of the time period, as shown in Table D-7.

The authors note that there was still room for improvement in having appropriate tuberculosis isolation rooms available, but noted that the high cost of construction would likely make this a slow process. They also noted a trend toward the adoption of more compliant personal respiratory protection consistent with the 1990 CDC guidelines.

The results of a survey of U.S. hospitals by the Hospital Infections Program (HIP) of CDC were reported by Manangan and colleagues (51). A sample of US hospitals from the American Hospital Association database was surveyed in 1992. The response rate was 763/1076 (71 percent). In 1996, hospitals that had had ≥6 tuberculosis admissions in 1991 were resurveyed.

The 1992 survey showed that from 1989 to 1991 there was an increase in the proportion of hospitals admitting patients with tuberculosis and in

TABLE D-7. Personal Respiratory Protection Trends from 1993 CDC-SHEA Survey

Percent

Respiratory Protection

1989

1990

1991

1992

Surgical mask

95

94

92

57

Submicron mask

4

5

5

20

Dust-mist respirator

1

1

3

13

Dust-mist-fume respirator

0

0

0

10

HEPA respirator

0

0

0

0

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

the numbers of tuberculosis patients admitted. Only 536/755 (71 percent) had tuberculosis isolation rooms meeting 1990 CDC criteria. A total of 648/727 (89 percent) had no appropriate tuberculosis isolation rooms in the ED. In 334/545 (61 percent), the air flow of tuberculosis isolation rooms was not routinely checked; of 211 hospitals that did routinely check air flow, 81 (38 percent) checked it annually, but only 28 (13 percent; 5 percent of total) checked it at least monthly. In 339/775 (44 percent) hospitals, doors to tuberculosis isolation rooms were left open at least some of the time. Patients were allowed out of isolation for other than medical reasons (e.g., to go to a lounge) in 451/734 (61 percent) hospitals by policy and in 517/734 (70 percent) in practice. Nosocomial transmission of tuberculosis to health care workers was reported by 96/716 (13 percent) hospitals, and 14/728 (2 percent) reported transmission to patients. For the 1996 survey, 136 hospitals resurveyed—103 (76 percent) responded. Comparisons of the answers in hospitals that responded in both 1992 and 1996 are shown in Table D-8.

The survey showed improvement in isolation rooms and maintenance. In 1992 few hospitals had implemented the 1990 guidelines, but the authors suggest that by 1996 “most had made progress in implementing recommendation in the 1994 CDC tuberculosis guidelines.” There was even a suggestion of reductions in nosocomial transmission of tuberculosis.

TABLE D-8. Comparison of 1992 and 1996 Responses to HIP (CDC) Survey

Measure

1992

1996

Tuberculosis isolation rooms meet CDC guidelines

59/92 (64)

99/103 (96)

Routine check for negative pressure in tuberculosis isolation rooms

72/85 (49)

96/99 (97)

At least monthly check

5/35 (14)

76/90 (84)

Mask use

 

 

Surgical mask

101/101 (100)

1/103 (1)

Particulate respirator

8/101 (8)

40/103 (39)

Dust-mist-fume respirator

 

4/103 (4)

HEPA respirator

 

36/103 (35)

N95 respirator

 

85/103 (83)

PPD testing program Covered Personnel

 

 

Nurses

103/103 (100)

103/103 (100)

RT

102/103 (100)

103/103 (100)

House staff

55/81 (69)

65/73 (89)

Attendings

43/86 (50)

65/94 (69)

Perform PPD after exposure

98/101 (97)

102/103 (99)

Maintain yearly reports

64/98 (65)

93/98 (95)

NOTE: Data represent number in that category/total number (percent).

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

Manangan and colleagues (52) also reported on results from New Jersey hospitals. In April 1992, a questionnaire was sent to all 96 New Jersey hospitals; 53 (55 percent) responded. In December 1996, a repeat survey was sent to the original 53 respondents, with 49 (92 percent) returning the survey (hospital mergers effectively changed the numbers to 51 and 47). The results are shown in Table D-9.

The health care worker PPD conversion rate peaked in 1991 and then fell (1989, 0.81 percent; 1991, 1.15 percent; 1996, 0.44 percent) and the total number of PPD tests done increased. However, in 1996 only 27/47 (57 percent) of hospitals could report the number of employees who had had a PPD test.

Like the national survey, the results from New Jersey showed increased compliance with tuberculosis precautions. The decline in the PPD conversion rate suggests, however, that there was also a drop in the number of tuberculosis patients admitted over the time period in the survey.

Likewise, a recently published survey of Maryland acute-care hospitals in 1997 was compared with a similar survey in 1992 and shows significant improvements in guideline compliance (53). The results are shown in Table D-10. However, only 41/56 (73 percent) hospitals responded, so the results may be overly optimistic.

Tuberculosis isolation procedures in 22 New York City hospitals from 1992 through 1994 were observed by Stricof and colleagues (54). Results are presented in Table D-11, shown as the percentage of room observations.

TABLE D-9. Results of New Jersey Hospital Survey

Measure

1992

1996

No. tuberculosis isolation rooms meeting CDC criteria

21/51 (41)

2/47 (4)

Had copy of 1994 CDC guidelines

n/a

47/47 (100)

Surgical mask used for PPE

28/51 (55)

 

N95 mask for PPE

 

45/47 (96)

Hospitals with nosocomial tuberculosis

2

0

NOTE: Data represent number in the category/total number (percent), n/a = not available

PPE = personal protective equipment

TABLE D-10. Results of Maryland Hospital Survey

 

Percent

Measure

1992

1997

p

Tuberculosis isolation rooms meeting CDC criteria

 

100

 

Tuberculosis rooms routinely checked

50

90

<0.01

EDs with tuberculosis isolation rooms available

50

90

<0.01

Compliant respirator used

24

100

<0.01

Protocol for identifying high-risk patient

 

49

 

At least annual PPD test for health care workers

50

98

<0.01

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

TABLE D-11. Tuberculosis Isolation Practices in New York City Hospitals, 1992–1994

 

Percent

Measure

1992

1993

1994

p

Tuberculosis patients in shared rooms

12.8

10.5

0

 

No private toilet in room

19.7

6.7

5.3

 

Room with negative pressure

51.3

70.5

80.3

<0.001

Room with HEPA filtration

1.7

20.0

27.6

 

Room with no negative pressure/HEPA/UVGI

32.5

14.3

6.6

 

Room door left open

5.1

3.8

5.3

 

Window in room open

19.7

12.4

9.2

 

Tuberculosis patient isolated on admission

75

 

84

0.02

Patient not isolated until + AFB reported

15

10

7

0.009

Dust-mist respirator

28

 

76

<0.001

AFB done 7 days/week

40

 

95

 

Tuberculosis case reported to health department

80

 

100

 

The discussion notes that improvements in case follow-up led to a decreased length of stay, so that fewer patients were in the hospital at any given time. Overall, there was significant improvement in compliance with CDC guidelines, although glitches (e.g., open doors and windows) persisted.

Unfortunately, as noted previously, survey results may give an incomplete picture. Sutton and colleagues (55) reported the results of a questionnaire and direct observation at three California hospitals (two county, one private-community) in an area where tuberculosis is highly endemic. This was done over 1 year (1994–1995, [exact dates not given]).

All of the hospitals had written tuberculosis plans consistent with CDC guidelines, but none of the hospitals performed routine assessment of their tuberculosis control practices. There were 13–17 tuberculosis isolation rooms available, including at least 1 each in the ICU and ED, at each hospital. Negative pressure was documented in 18/25 (72 percent) tested rooms, and 19/22 (86 percent) tested rooms had ≥6 ACH (6/16 [38 percent] had ≥12 ACH, even though they were not new rooms). However, only 1/27 (4 percent) rooms tested met recommended airflow pattern, and 20/24 (83 percent) had poor-fair air mixing (<10 seconds for puff of smoke to disperse, equivalent to ≥2 breaths for health care workers). The latter measurements are rarely reported in other studies.

One hospital provided HEPA masks with a fit testing program, one used dust-mist (DM) masks without a fit testing program, and one used DM masks but had HEPA masks with fit testing available (but the paper notes that in practice these were not used).

Practices noted on direct observations included lack of regular checks of negative pressure; windows that could be opened (with potential changes

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

in airflow) in 44 percent of rooms; no engineering controls in a chest clinic that saw tuberculosis patients; and unmasked tuberculosis patients leaving room to smoke, use a phone, watch television, use a bathroom (the number of tuberculosis isolation rooms without bathrooms was not stated).

Thus, measures that would have been on a typical survey tool would have shown good results. However, the practices were sometimes poor. In addition, parameters that are rarely checked (e.g., airflow patterns and air mixing) may not be optimal according to the guidelines, even if other criteria for a tuberculosis isolation room are met. The actual significance of this is unknown.

Tuberculosis control practices at facilities for children were the focus of an APIC-CDC survey of children’s hospitals and hospitals with pediatric units with >30 beds (56, 57). The survey covered 1990 to 1994. Overall, 195/284 (69 percent) hospitals responded (including 63/83 [76 percent] of freestanding children’s hospitals). Part I of the survey (56) reviewed isolation policies. There was an increase in total tuberculosis cases tuberculosis and resistant tuberculosis reported over the survey period.

Control practices implemented by the hospitals included the following:

  • 175/178 (98 percent) isolated patients with cavitary disease

  • 176/179 (98 percent) isolated patients with AFB+ smears

  • 120/175 (69 percent) isolated patients with miliary tuberculosis

  • 138/175 (79 percent) isolated patients with AFB + gastric aspirates

  • 9/179 (5 percent) allowed patient to leave room for nonmedical reason

  • 96/139 (69 percent) restricted parents/adult visitors to isolation room

  • 57/135 (42 percent) denied visiting privileges of parents until a tuberculosis evaluation done

  • 40 percent of hospitals inappropriately required patients to wear dust-mist-fume (DMF) or HEPA masks when out of room

A total of 14 “clusters” of ≥2 PPD conversions among health care workers were reported from 11/191 (6 percent) hospitals, with one child PPD conversion reported.

Part II of the survey (57) reviewed the physical facilities available for tuberculosis control at the hospitals. Results included the following:

  • 166/194 (86 percent) had facilities to care for a child with tuberculosis

  • 78/190 (41 percent) had a pediatric-specific tuberculosis policy

  • 83/187 (44 percent) stated that 1994 OSHA compliance memorandum caused change in policy

  • 158/171 (92 percent) had isolation room with ≥6 ACH

  • 153/170 (90 percent) vented air directly to outside

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×
  • 153/170 (90 percent) had negative pressure

  • 158/177 (89 percent) used private rooms for isolation

  • 23/170 (14 percent) used UV in room, 4/170 (2 percent) used UV on exhaust

  • 32/167 (19 percent) used portable HEPA in rooms

  • 73/174 (42 percent) had isolation rooms in outpatient areas

  • All had an employee PPD program

  • 182/186 (98 percent) performed at least annual PPD testing for health care workers

  • 182/184 (99 percent) used the Mantoux test

  • 114/167(68 percent) used two-step testing of new employees

From 1991 to 1994 surgical mask use dropped from ~86 percent for procedures/isolation room use to <33 percent. The use of DM and DMF masks increased, as did HEPA mask use (from 3 hospitals in 1991 to 62 hospitals in 1994). Overall compliance was thought to be good.

Rapid Specimen Processing

Rapid processing of smears for AFB and cultures is part of the CDC guidelines. This is to allow the prompt diagnosis of tuberculosis and also to allow patients without tuberculosis to have isolation discontinued in a timely fashion. Tokars and colleagues (58) reported on a survey of labs by the HIP and the Division of Tuberculosis Elimination at CDC. A total of 1,076 hospitals with ≥100 beds were surveyed in 1992 with a 70 percent response. Twenty percent of the responding labs were resurveyed in 1995. The results for hospitals included in both surveys are shown in Table D-12.

The discussion notes an overall improvement in following recommended procedures, with a concomitant decrease in reporting times. The authors suggest that if tuberculosis case rates continue to decline, consolidation of tuberculosis testing to a smaller number of labs may be desirable, especially since there is still considerable room for improvement in meeting recommended techniques.

TABLE D-12. Improvements in Laboratory Testing for Tuberculosis

Recommended Test

1992

1995

Fluorochrome stain for microscopy for AFB

44%

73%

Radiometric methods for primary culture

27%

37%

Rapid method for M. tuberculosis identification

59%

88%

Radiometric method for sensitivity testing

55%

75%

Median time for reporting smear for AFB

2 days

1 day

Median time to M. tuberculosis identification

40 days

21 days

Median time to susceptibility report

45 days

35 days

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

Education

LoBue and Catanzaro (59) studied health care worker compliance with tuberculosis control policies at the University of California at San Diego. This hospital implemented tuberculosis control policies consistent with the 1990 CDC guidelines in 1992 (60). Direct observations of health care worker behavior was made over a 14-week period (the year is not given). There were 115 sessions of 60 to 120 min for 52 patients on isolation, with a total of 541 health care worker observations made

Overall, 64 violations were observed—36 failures to maintain isolation (e.g., leaving door open) and 28 failures to use masks properly. Residents/fellows had 0.34 violations/observation, medical students had 0.28 violations/observation, prison guards had 0.5 violations/observation, and housekeepers had 0.38 violations/observation. Respiratory therapists had 5 violations in 3 observations (1.67 violations/observation), but these data were not included in analysis because there were less than five observations. Aides/transport and nurses did very well (0.02 and 0.08 violations/observation, respectively); they also had the most observations.

Physicians in training (medical students, residents, and fellows) committed 45 percent of violations (contributing 17 percent of observations). Of 29 violations, 8 were judged to be “technical” and of no clinical significance, in that an order to discontinue isolation was made prior to or shortly after observation (but a sign was still on the door, so it was counted as a violation).

Overall compliance was judged to be OK, but the authors suggest that additional education was needed, especially among physicians in training. As in other papers, this study points out that having a policy consistent with the CDC guidelines is not the same as following the policy.

Lack of health care worker knowledge at the University of Massachusetts was the focus of a study by Lai and colleagues (61). A test was administered in August 1993 to 200 health care worker with patient contact. Ninety-five (48 percent) reported having some tuberculosis education within the previous 2 years.

Overall, 195 (98 percent) knew that tuberculosis could be spread by coughing/sneezing. However, 55 (28 percent) thought that it could be spread by shaking hands. A total of 175 (88 percent) knew that masks should be used when entering the room of a tuberculosis patient. However, 70 (35 percent) would also use gowns. The study showed a surprisingly high lack of knowledge of how tuberculosis is transmitted.

IMPLEMENTATION IN NON-INPATIENT SETTINGS

Studies of tuberculosis control outside of the acute-care hospital inpatient setting are uncommon. Many of the articles retrieved by literature

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

search are simply reviews of tuberculosis and tuberculosis control with some suggestions at implementing control measures in whatever setting rather than studies of actual practices or outcomes.

Emergency Departments

Moran and colleagues (62) reported the results of a 1993 CDC survey of tuberculosis control practices in the ED. Written policies for managing patients with suspected tuberculosis in the triage and waiting areas were available at 159/282 (56.4 percent) hospitals. A total of 214/280 (76.4 percent) had written policies for the ED proper. The decision to isolate patients was usually made in triage (235/286 [82.2 percent] hospitals). Written criteria for this decision were available in 105/286 (44.7 percent) hospitals. Patients suspected of having tuberculosis were given a mask in 228/246 (91.9 percent) of institutions. A total of 5/247 (1.7 percent) had tuberculosis isolation rooms in the triage/waiting area, while 56/286 (19.6 percent) had tuberculosis isolation room in the ED proper. UVGI was used in 15/277 (5.4 percent) triage/waiting areas and in 21/264 (8 percent) EDs proper. Air was recirculated in 211/262 (81 percent) of triage areas and 205/258 (79 percent) of EDs proper.

An employee PPD program was in place at 283/286 (99 percent). A total of 186 (65.7 percent) were tested annually, 58 (20.5 percent) were tested every six months, and 18 (6.4 percent) were tested only at hire. For 1991, 34/211 (16.1 percent) had >1 PPD conversion; for 1992 this changed to 63/234 (26.9%). The overall rate of PPD conversion in 1991 was 78/ 7,348 (1.1 percent) whereas it was 141/8,698 (1.6 percent) in 1992.

This study showed that in the early 1990s, compliance with suggested control measures for EDs was suboptimal, along the lines of general compliance discussed above.

Dental Clinics

Murphy and Younai (63) report on a study done at the New York University College of Dentistry. This school runs an extremely busy clinic with 288,000 patient visits/contacts per year in New York City. From 1991 it had gradual implementation of annual PPD testing for faculty, staff, and students. For the 1993–1994 testing period, there was a 20.9 percent conversion rate in employees (56 percent of these conversions were in employees with no patient contact) and a 15 percent conversion rate in students. To evaluate for possible tuberculosis exposures in the clinic, the authors conducted a retrospective review of patients referred out for a medical condition from August 1994 through July 1995. A total of 96/ 1,259 (0.4 percent) of the referrals were potentially related to tuberculosis—a review of those who returned to dental care and had records avail-

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

able showed no cases of patients with active tuberculosis at time of their dental visit. These chart review data were also reported separately in greater detail (64).

The authors conducted a survey of 54 dental schools and received 24 (44 percent) responses. A total of 14/24 (58 percent) had no PPD data available, and 5 (21 percent) had no data available but were planning to start testing. Of five (21 percent) with data, only three shared their results. At one dental clinic on the West Coast, the PPD conversion rate was approximately 1 percent. At another West Coast school, the conversion rate for faculty was 1.6 percent, for students it was 2 percent, and for staff it was 1.8 percent. At the third school, in the Midwest, the only positive PPD results were in foreign-born students.

A 1-year study, completed in July 1995, of student conversions during the 3rd year (the first clinical year) revealed a 10.6 percent conversion rate. It was unclear if students had received two-stage testing for their initial tests.

The control plan for the facility involved a risk analysis, after which the facility was designated very low risk (i.e., tuberculosis in the community but not the facility). The paper speculates that a lot of the skin test conversion may have been community acquired. Administrative controls included obtaining a detailed history from every new patient and an abbreviated history on patient return to screen for tuberculosis; patients with suspicious findings were sent to a designated clinic for more detailed evaluation. HEPA masks were made available and were to be used for high-risk patients. Engineering controls are not required at that risk level, and none were specifically planned.

Although no cases of tuberculosis were found by their chart review, given the high prevalence of tuberculosis in New York City during that time period and given the high rates of PPD conversions in students and faculty, a higher-level risk assessment would seem more appropriate. An argument could be made for implementing more aggressive control measures, especially engineering controls in common areas, and perhaps better personal protective equipment for the staff.

COSTS OF IMPLEMENTING GUIDELINES

Entire Guidelines

Kellerman and colleagues (65) calculated the costs from 1989 to 1994 of implementing the CDC guidelines at three New York City hospitals (Roosevelt, Cabrini, St. Clare’s) and a Miami hospital (Jackson) that had had nosocomial outbreaks. Also included was one low-risk hospital in Nebraska (Regional West) for comparison. The hospitals provided estimates of nursing time for placing and reading PPD tests, supply costs,

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

and costs of follow-up of those with positive PPD test results. The absolute costs of an employee PPD program ranged from $330 to $58,380 per year. The cost per health care worker tested ranged from $3.53 to $12.94. Additional personnel costs for administering a tuberculosis control program ranged from $10,000 (0.25 full-time equivalents [FTE]) to $137,400 (2 FTE). Capital costs for environmental controls ranged from $54,000 to $554,900. Maintenance costs (including increased utility costs due to increased ventilation) were estimated at $4,000 to $25,000 per year.

Kellerman and colleagues (66) also evaluated the costs of tuberculosis control in children’s hospitals in 1994–1995. The Baby and Children’s Hospital-New York Presbyterian Medical Center (BCH-NYPMC) Children’s Hospital and Health Center-San Diego (CHHC-SD), and the pediatric ward at the University of California at San Diego (UCSD) were surveyed. Costs per health care worker for PPD testing ranged from $6.91 to $12.49, with total costs of the program running $2,470 to $26,577 per year. Construction costs for that year ranged from $12,800 to $24,500. Total respirator costs for a year were $1,360 at BCH-NYPMC (with fit testing by manufacturer), $1,680 at CHHC-SD (fit testing was available but was not used), and $480 at UCSD (no fit testing).

While the “data” aspects of the implementation of control measures at Roosevelt in New York City were reviewed by Stroud et al. (18), Williams et al. (67) provided a discussion of the “soft” aspects of the control program. A primary barrier early on was a lack of tuberculosis knowledge by health care workers, which required providing significant education efforts. Because much of the tuberculosis at Roosevelt came through the ED, the medical director there played a key role in educating that department. This led to more timely isolation in the ED.

They noted that a key priority was enlisting the collaboration of the admitting department so that patients could be moved out of the ED in a timely fashion. They developed a system of bed triage based on estimated risk so that tuberculosis isolation rooms would be used appropriately in times of shortage.

Getting health care workers to implement controls was hampered by the perception that prevention of tuberculosis outbreaks was solely the responsibility of infection control, which had “failed” since an outbreak had occurred. Also, the increased numbers of patients on isolation increased the perception that more tuberculosis patients were being admitted, increasing employee fear and anger. However, the concerns of health care workers did spark increased compliance with routine PPD testing.

The authors noted that one key difficulty was keeping patients in their rooms. They tried offering incentives (e.g., free television, free incoming phone calls, special food choices) as suggested in the CDC guidelines, but noted that the actual impact was small. Although this paper does not address any dollar costs in implementing control measures, it

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

provides an excellent review of the social costs of an outbreak and associated controls.

Isolation/Administrative Controls

A significant fraction of the ongoing cost of a tuberculosis program may be in evaluating patients who do not have tuberculosis but who meet criteria to be evaluated. Scott and colleagues (68) evaluated the experience at the University of Iowa Hospital and Clinics. All patients with a positive sputum culture for tuberculosis between January 1, 1987, and September 24, 1992, were considered a case. Forty-four patients were identified, and charts were available for review for 43. Control patients were chosen randomly from patients who had had sputum submitted for AFB but who had negative cultures. Since bronchoscopy specimens were routinely sent for AFB smear and culture regardless of clinical suspicion of tuberculosis, patients who had specimens only from bronchoalveolar lavage were excluded. Of 92 potential controls for every case, 43 random controls chosen matched by location (inpatient/outpatient) and service.

Of the case patients, 39 (91 percent) were smear positive; 25 (58 percent) were positive on the first smear. Only one test for AFB was sent from 48 percent of the control subjects. Of 24 inpatients with pulmonary tuberculosis, only 10 (42 percent) were isolated upon admission. A total of 37/ 43 (86 percent) case patients had a CXR consistent with tuberculosis, as did 7/43 (16 percent) controls. If same rate held for all patients, ~670 patients would have had abnormal CXRs. The six other case patients had abnormal CXRs, but not “typical” for tuberculosis. From July 1, 1991, through June 30, 1992, there were 12 “exposure” workups for an AFB+ smear, with 363 contacts. Only 4 of the 12 had tuberculosis; the others had infection with non-tuberculous mycobacteria (NTM).

Scott and colleagues (68) calculated the cost of diagnosing a case of tuberculosis: $18.30 was spent for an AFB smear and culture. Control patients had an average of 2 sputum specimens sent, while case patients had an average of 3.2 specimens sent. With 92 control patients for every tuberculosis patient, this led to a cost of $3,426 per case of tuberculosis diagnosed. The authors also estimated that 15 minutes/person of nurse epidemiologist time was spent tracing and contacting health care workers exposed to a case of tuberculosis, with an additional $6.00 to $11.00 per employee for PPD testing.

The authors state that a policy of isolating everyone for whom an AFB smear was sent would be unreasonable, causing a 92-fold overuse of isolation rooms. However, this is within the range reported in the Veterans Affairs hospital study by Roy et al. (30). Although not discussed, if only the estimated 670 patients with “typical” CXRs were isolated, the overisolation ratio would be ~18:1, which does not seem unreasonable.

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

It would seem that the ordering of testing of sputum for AFB at Iowa at that time period was excessive, especially given that almost half of the control patients had only one sputum specimen sent. Despite this apparent interest in diagnosing tuberculosis, only 42 percent of tuberculosis patients were isolated on admission. One wonders if physicians are lulled into complacency about tuberculosis since so many of the positive AFB smears proved to be NTM. This increase in NTM compared with tuberculosis has been reported elsewhere (21, 69) as well.

Although the authors did not calculate this, using their estimate of 30 contacts per case, the 14 nonisolated tuberculosis patients would have exposed 420 health care workers at a cost of 105 nurse epidemiologist hours ($2,100 at the $20/hour they estimated), plus an additional $2,520 to $4,620 for PPD testing.

Kerr and Savage (70) calculated the potential cost of exposure to a single nonisolated patient in a postanesthesia care unit (PACU). Based on traffic in the PACU and typical recovery times, they estimated that a patient with tuberculosis would expose 24 other patients, 10 PACU staff, 38 operating room staff, and 9 ancillary staff (total 81). Cost and time estimates were from Brown et al. (70) and Scott et al. (67). Their results follow:

Cost per contact identification

 

$17.00

PPD testing cost

 

$8.21

Total contact tracing/testing

$25.21 * 81 =

$2,042.01

Legal/risk management

 

$550.00

Infectious disease consult

 

$200.00

Total initial costs

 

$2,792.01

Follow-up 65 with negative initial

 

 

PPD test

$8.21 * 65 =

$533.65

Follow-up for 16 PPD conversions

 

 

Physician visit, smear, CXR

$88.30 * 16 =

$1,412.80

Follow-up for 3 with active disease

 

 

Hospital costs

$12,369.00 * 3 =

$37,107.00

Physician visits

$1,785.00 * 3 =

$5,355.00

Follow-up for 13 with latent tuberculosis

 

 

6 months of INH @ $7.20/month

 

$562.38

Monthly nurse visits @ $20.00/month

 

$1,560.00

Follow-up physician exam @ $45.00

 

$585.00

Follow-up CXR @ $25.00

 

$325.00

Grand Total

 

$57,477.84

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

Although one can take exception to some of the estimates, the values chosen for baseline PPD test positivity, PPD conversion, and development of active disease are all within reasonable ranges. The conversion rates were cited from Griffith and colleagues (72). The rate of developing active tuberculosis seems high (albeit possible), and the need for inpatient therapy seems unlikely. For outpatient therapy of tuberculosis, Brown et al. (71) list $2,300/case for drug-susceptible tuberculosis (health department data). Nevertheless it is clear that one tuberculosis exposure can be quite expensive if one figures in all the costs involved and not just contact tracing and a single round of PPD testing.

A study submitted for publication by Topal and colleagues (73) and associates at Yale University reviewed their experience with isolation protocols. Because their case finding included all patients for whom a sample for testing for AFB was sent, even if only from a bronchoscopy specimen, it is difficult to compare their results with those of others.

Their initial protocol required tuberculosis isolation if a patient had cough for ≥2 weeks AND infiltrate on CXR AND a risk factor (tuberculosis exposure/history of tuberculosis or positive PPD/HIV infection/homelessness/IV drug use/alcohol use OR [fever + weight loss + night sweats]). Patients were evaluated from October 1996 through June 1997. In the initial group, 48/141 (34 percent) of isolated patients (19 percent of total patients for whom cultures for AFB testing were sent) did not meet isolation criteria and were considered over-isolated. Twenty-one of these were HIV-infected patients. At least one patient who was over-isolated by their criteria had tuberculosis. This patient had a cough and an abnormal CXR, but no clinical symptoms or risk factors on their list. He was from India and had been isolated anyway. A total of 13/115 patients for whom AFB tests were ordered and who were not placed on isolation actually met the criteria, and should have been isolated. One such patient with tuberculosis exposed 200 health care workers (no PPD conversions were found on follow-up).

The protocol was revised to allow for clinical concern in HIV-infected patients. The revised protocol also included foreign birth in an area with high prevalence of tuberculosis as a risk factor. A postintervention study was done from January through June 1998, after educating health care workers about the new guidelines. Only 12.6 percent of the group were over-isolated, and only 2 (1.5 percent) patients were under-isolated. Thus, their educational intervention was successful, and apparently, with the new criteria, no patient with tuberculosis was not isolated. Overall, the new criteria had increased sensitivity (80 versus 100 percent) with a loss of specificity (50 to 40 percent).

Although it is not clear from the data in the results, the authors state in the discussion that their over-isolation ratio was 25:1 in the post-intervention period. Their cost estimate for smears for AFB and culture was $50.00 (it is implied that this is for three sputum samples). Thus, labora-

Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

tory costs for a 25:1 over-isolation are $1,250 spent for every case of tuberculosis diagnosed. They also estimate respirator costs at $5.00 to $6.50 per day ($0.50/mask with 10–13 used/day), and with a mean duration in tuberculosis isolation of 4.2 days, respirator cost would be about $700 for 25 patients. This leads to a total laboratory and isolation cost of under $2,000 for every patient actually diagnosed with tuberculosis (the authors actually calculate a cost of approximately $3,000 per case, but their calculation assumes that every patient isolated stays on isolation for the duration of their stay, about 10 days). If one patient exposed 400 health care workers (as had happened at Yale in 1993), labor costs alone were estimated at $11,000. Thus, even if there were no PPD converters, they suggest that their 25:1 over-isolation ratio may be cost-effective.

Education

Trovillion and colleagues (37) reported on the costs of implementing an educational program. A tuberculosis protocol was introduced at BarnesJewish Hospital in St. Louis in the summer of 1995. An estimated 3,000 employees with patient contact (35 percent of total) needed training. Because this was beyond the means of the infection control practitioners, 146 volunteer trainers were instructed and provided with training materials. These trainers then provided training sessions at their respective locations.

Only 924 employees (31 percent) received training within 6 weeks as was requested. By the end of 5 months, 1,909 (64 percent) of targeted employees had been trained. The sessions tended to last ~20 minutes because of time constraints, not the 40 minutes envisioned during the training of the trainers.

The estimated costs were infection control program development time (40 hours) ($1,386) + training packets ($812) + employee time away from workplace to provide/attend training ($23,855), for a total of $26,053. Excluding the cost for the employees to attend, which would be incurred by any training method, this format was thought to be a cost-effective way of providing efficient training. No hard evidence of the effectiveness of the training was obtained, but the discussion mentions that staff seemed to be more knowledgeable.

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Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

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Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

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Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

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Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
×

55. Sutton PM, Nicas M, Reinisch F, Harrison RJ. Evaluating the control of tuberculosis among healthcare workers: adherence to CDC guidelines of three urban hospitals in California [see comments]. Infection Control and Hospital Epidemiology 1998; 19:487–493.

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Suggested Citation:"Appendix D Effects of CDC Guidelines on Tuberculosis Control in Health Care Facilities." Institute of Medicine. 2001. Tuberculosis in the Workplace. Washington, DC: The National Academies Press. doi: 10.17226/10045.
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Before effective treatments were introduced in the 1950s, tuberculosis was a leading cause of death and disability in the United States. Health care workers were at particular risk. Although the occupational risk of tuberculosis has been declining in recent years, this new book from the Institute of Medicine concludes that vigilance in tuberculosis control is still needed in workplaces and communities. Tuberculosis in the Workplace reviews evidence about the effectiveness of control measures—such as those recommended by the Centers for Disease Control and Prevention—intended to prevent transmission of tuberculosis in health care and other workplaces. It discusses whether proposed regulations from the Occupational Safety and Health Administration would likely increase or sustain compliance with effective control measures and would allow adequate flexibility to adapt measures to the degree of risk facing workers.

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