Summary of Individual Reports Notwithstanding their limitations, taken together, the studies reviewed above suggest that implementation of tuberculosis control measures can help end outbreaks and prevent new transmission of M. tuberculosis. They support the logic of CDC’s emphasis on the primacy of administrative controls, in particular, rigorous respiratory isolation policies to reduce exposure opportunities by promptly identifying, evaluating, and isolating people with signs and symptoms suspicious for tuberculosis. The studies suggest some positive effects from engineering controls, which come second in CDC’s hierarchy of controls, but their contributions are hard to disentangle from the effects of previously or simultaneously adopted administrative controls. Personal respirators did not appear to play a significant role in ending outbreaks of tuberculosis.
In recent years, hospitals may also have benefited from changes in the treatment patterns including both a shift from inpatient to outpatient treatment for people with infectious tuberculosis and the availability of more effective treatments for AIDS that have reduced the need for inpatient care. Continued reports of outbreaks in correctional facilities in South Carolina and Pennsylvania (see Chapter 5) suggest the need for better information on surveillance programs and other tuberculosis control measures in these settings.
In addition to the reports reviewed above, the committee found some additional relevant studies that involved mostly low-risk or stable settings.5 One study reviewed tuberculosis control measures in 13 midwestern hospitals, all but one of which were categorized as low or very low risk for transmission of tuberculosis. The researchers did not find an association between the kinds of tuberculosis control measures adopted and worker skin test conversion rates (Woeltje et al., 1997). The study did not examine isolation policies, and the authors noted that compliance with written policies for other measures was imperfect.
In one of the few studies examining a single control measure, Behrman and Shofer (1998) report on an emergency department that adopted improved engineering controls while leaving isolation and respiratory pro-
Appendix D reviews several surveys that asked questions about the implementation of tuberculosis control measures and about results of worker skin testing programs. Analyses of the association between control measures and conversion rates produced inconsistent results. Given the variations in response rates, the limited detail possible in survey responses, and similar concerns, the committee did not find that these analyses contributed to its understanding of the effects of the CDC guidelines.