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Review of the NCHS Plan for the National Health Care Survey OVERVIEW As discussed in Chapter 2, major changes in the organization, financ- ing, and delivery of health care have outpaced the capabilities of existing national health care surveys to provide relevant and timely data to monitor the health care of the nation and evaluate the impact of the changes in the system. Although extensive national data activities exist, they are not ide- ally designed to yield the kinds of data needed for monitoring and evaluat- ing the changes occurring in the nation's health care system or for health policy analysis and development. (Brief descriptions of some of the nation- al health data systems maintained by the U.S. Department of Health and Human Services are presented in Appendix C). In an effort to be responsive to various emerging national health care issues and to the associated data needs, the National Center for Health Statistics (NCHS) in 1986 undertook a review of its existing surveys of health care providers. As a result of this review, NCHS has developed a plan for restructuring its existing health care provider surveys into a new National Health Care Survey with the aim of providing a more complete and useful picture than now exists of the medical care provided in the United States. The center's plan for the survey is described in the docu- ment entitled, "The National Health Care Survey" (reproduced in Appendix A). This document was supplemented by additional material provided by 4 1
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42 TOWARD A NATIONAL HEALTH CARE SURVEY NCHS as it became available as well as presentations to the panel by NCHS officials. According to the plan, the proposed National Health Care Survey will build on the four existing health care provider surveys, which will be merged, expanded over time, and linked geographically with the National Health Interview Survey (NHIS). The provider surveys are the National Hospital Discharge Survey, the National Ambulatory Medical Care Survey, the Na- tional Nursing Home Survey, and the National Master Facility Inventory. Table 1 is a profile of the current survey design for the NCHS health care provider surveys and the National Health Interview Survey. The primary objective of this new survey will be "to produce annual data on the use of health care and the outcomes of care for the major sectors of the health care delivery system. These data will describe the patient population, medical care provided, financing, and provider characteristics" (see Appendix A). The NCHS proposes to implement the National Health Care Survey over a period of years as resources petit. The phased implementation of the new survey design began in 1988. The proposed survey has four main features: (1) The survey will be conducted on an annual basis to eliminate gaps in data and fluctuations in resource requirements; (2) The types of providers and settings sampled would be expanded to include an array of additional sites of health care, such as hospital emergency and outpatient departments, ambulatory surgery centers, home health agencies, and hospices; (3) Sampling designs will be revised. An integrated three-stage cluster design will be used in which providers would be sampled from a subsample of the primary sampling units (PSU)~ of the National Health Interview Survey, and (4) A capability would be developed to conduct routine and specialized patient follow-up studies to examine issues related to the outcome and subsequent use of medical care. By expanding the types of providers surveyed and by adding a follow- up component, NCHS hopes to enhance the kind and amount of information currently available about health care events. iFor the first stage of sample design for the National Health Interview Survey in which the civilian noninstitutionalized population residing in the United States is sampled, the United States is considered to be a universe composed of approximately 1.900 geographically defined primary sampling units. A primary sampling unit consists of a county, small group of contig- uous counties, or a metropolitan statistical area. The PSUs collectively cover the 50 states and the District of Columbia.
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REVIEW OF THE NCHS PLAN 43 The panel reviewed the center's plan for an integrated National Health Care Survey from two perspectives: (1) technical features of the plan and ~2) the extent to which the survey would enable NCHS to meet the changing data needs associated with the health care policy issues discussed in the previous chapter. The following sections present the panel's review. PERIODICITY One feature of the center's plan is the annual data collection schedule planned for each provider survey. In recent years, primarily because of resource limitations, the average time between cycles of these surveys has increased si~,r~ificantly. The center correctly argues that funding and staff- ing these surveys on an on-again, off-a~ain basis is not sound from a man- agement, fiscal, or statistical point of view. in fielding annual surveys, including, maintaining a small group o~ wc~- trained staff, reducing the budgeting and scheduling problems associated with periodic surveys, minimizing recurrent start-up costs for survey com- ponents, addressing the seasonal nature of illness, and providing current statistics. In order to offset the increased costs of conducting the provider surveys annually, however, the center clans to reduce their sample sizes. Reducing It points to several advantages -berm- By , ample sizes obviously works against solving the general problem of pro- ducing data for subdomains of the population. The sample sizes of these surveys are too small now for subnational estimates, for estimates of diag- nosis and treatment of rare conditions, and for statistics on minorities. With reduced sample size the problems of developing estimates for small areas and various subpopulations of interest appear to be aggravated. The center plans to compensate for smaller sample sizes by aggregating data for more than one year. Although multiyear aggregation will be a necessity with the small samples, it is not clear how many years of aggrega- tion will be necessary to produce some of the statistics needed. Further- more, such aggregation may be less appropriate for characteristics that are not stable across years. It also will affect the timeliness of data production and analysis. The users of data who were surveyed expressed interest in estimates below the national level, at the state level, and even at the county or com- munity levels. The list of subpopulations of interest identified includes blacks, Hispanics, American Indians, Asians, disabled people, rural popula- tions, specific industrial groups, elderly people, children, especially dis- abled children, groups defined by socioeconomic level, and people in insti- tutions. The Disadvantaged and Minority Health Improvement Act of 1990, which contains the reauthorization of NCHS, also requires the center to develop better systems to collect data on minority subpopulations. Al-
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46 TOWARD A NATIONAL HEALTH CARE SURVEY though not all of these expectations are realistic for national survey-based data systems, the reduced annual sample sizes planned for the National Health Care Survey will undoubtedly further aggravate the problems of developing estimates for small areas and various subpopulations at a time when NCHS is looking for ways to improve responsiveness in these areas in a cost-effective manner. The panel seriously doubts the possibility of pro- ducing small area estimates even with the proposed aggregation of data over multiple years. The panel is informed that the NHIS sample is being redesigned to increase the sampling of PSUs in which blacks and Hispanics are concen- trated. Since the National Health Care Survey will be conducted in a sub- sample of the NHIS PSUs, the NHIS redesign should somewhat strengthen the samples of blacks and Hispanics in the National Health Care Survey as well. However, the panel does not believe that this increase in the sampling of NHIS PSUs in which blacks and Hispanics are concentrated will improve significantly the ability of the National Health Care Survey to provide health care statistics for minority populations. Despite the sample size deficiency, the panel believes that there are clear advantages to fielding the provider surveys on an annual basis, to reduce fluctuations in resource requirements and to ensure currency of the statistics. Recommendation 3-1: The panel endorses the NCHS plan to conduct the components of the National Health Care Survey on an annual basis. SCOPE AND COVERAGE . Current NCHS plans call for extending the coverage of the National Health Care Survey beyond the current four major health care provider surveys to include collection of national data for selected alternative sites of the three major types of health care and health care providers hospital care, ambulatory care, and long-term care: · The Hospital and Surgical Care Component, based on the Nation- al Hospital Discharge Survey (NHDS), is being modified to include hospital-based and free-standing ambulatory surgery centers. The Ambulatory Care Component, based on the National Ambu- latory Medical Care Survey (NAMCS), is being modified to in- clude medical care provided in emergency rooms and outpatient departments and clinics in nonfederal, short-term (i.e. average length of stay less than 30 days) hospitals. Long-range plans call for inclusion of additional settings, such as community and neighbor- hood health clinics.
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REVIEW OF THE NCHS PLAN 47 The Long-Term Care Component, based on the National Nursing Home Survey (NNHS), is being expanded to include board and care homes that provide assistance with activities of daily living, but not nursing or medical care. This addition will extend the survey to group homes, rest homes, and other supported living arrangements, including sites that provide service to the mentally and physically limited population. The long-term care component will be modi- fied further by the inclusion of a home health care and hospices survey. . The National Master Facility Inventory is being renamed the Na- tional Health Provider Inventory (NHPI) and expanded to in- clude hospices, home health care agencies, and licensed residential care facilities. Long-range plans call for the addition of providers of acute ambulatory care and community-based long-term care to the inventory. The panel endorses the center's efforts to extend the coverage of the provider surveys to include a range of the alternative health care settings that have emerged in recent years. The proposed extensions constitute an important step in extending the coverage of these surveys. However, they are only a first step if NCHS is to meet its responsibilities to provide a comprehensive coverage of national health care statistics in the United States. An important further extension needed is the inclusion of services pro- vided by nonphysicians who deliver health care. The panel's survey of users identified at least 37 types of providers and health care settings not currently being surveyed by NCHS, but for which health care statistics are needed (see Appendix B for the list of providers identified by users). Some of these health care settings are already under consideration for inclusion by NCHS. Others may not be appropriate for national surveys. Some obvious examples of additional providers for consideration are psychologists, den- tists, physical and occupational therapists, pharmacists, podiatrists, chiro- practors, nurses, nurse practitioners, physician assistants, nurse midwives, and optometrists, all of whom deliver some form of health care. Another specific concern is the distinction made historically by NCHS between collection of data on the physical health services that it plans to cover, and collection of data on mental health and dental services, which are not included in the center's plan. Such a distinction seems to reflect bureaucratic issues rather than theoretical coherence. Obviously, it would not be cost-effective for NCHS to attempt to duplicate the data collection efforts of the National Institute of Mental Health, the National Institute of Dental Research, or the Health Resources and Services Administration. The panel believes, however, that NCHS should consider the collection and/or
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48 TOWARD A NATIONAL HEALTH CARE SURVEY dissemination of adequate statistics about mental health and dental services to be part of its responsibility; it should furthermore ensure, perhaps through collaborative efforts, that the needed data in these areas are available from appropriate agencies and that they are collected in a form that is consistent with that used in the other provider surveys. Finally, though ambulatory care coverage is the area most in need of expansion beyond the current plan, the hospital care component also needs to be expanded. The omission of federal hospitals and long-term care hos- pitals from the hospital care component is a significant deficiency. NCHS has made efforts in the past to obtain data on federal hospital discharges, and the task has proven difficult. While recognizing the difficulties, the panel nevertheless considers that it would be desirable to have integrated data on all hospitalizations, including those in federal hospitals. Recommendation 3-2: The panel recommends that NCHS ex- tend its coverage of providers of health care to include a fuller range of health providers than currently planned both physi- cians and nonphysicians. The panel further recommends that the universe for the hospital care component be extended to include long-term care hospitals and federal hospitals. The panel does not mean to suggest that all possible health care provid- ers should be surveyed each year. A strategy needs to be developed for sampling types of providers at varying periodicities, with priorities based on their relative importance. For instance, periodicities for specific provid- er groups could be based on such considerations as expenditures for care, distribution and volume of users, political or policy issues of importance, and availability of resources. Certain categories of providers may have to be approached through periodic special studies. At the present time, however, no objective process exists for deciding which providers should be given priority for inclusion in the surveys, ex- cept availability of resources from the parties interested in the data. A mechanism is needed t-or developing standard criteria for setting priorities for incorporating nets ad emerging settings and the full range of health care providers, as we .~ for periodic review and revision of these criteria as needed. Recommendation 3-3: The panel recommends that NCHS put in place a mechanism for developing criteria and for setting data collection priorities across the full range of health care providers and service settings, and that this mechanism and process be dynamic and include periodic review and revisions of both the criteria and coverage as necessary.
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REVIEW OF THE NCHS PLAN 49 DATA COLLECTED The panel was asked to review the content of the questionnaires and definitions used in the provider surveys in terms of appropriateness and adequacy. The panel is in general agreement with the content areas includ- ed in the center's plans; however, it finds the coverage of the data content deficient in terms of what is needed to address current and future health care policy issues, as described in Chapter 2. The panel recognizes that any significant expansion or change in the data collected in the National Health Care Survey will require a major increase in the level of effort and associat- ed resources. Nonetheless, the panel has identified several key issues that are not reflected either in the content of existing surveys or in the plan for the proposed National Health Care Survey in its current stage of develop- ment; they are discussed below. The provider surveys that serve as the basis for the National Health Care Survey proposed by NCHS currently collect data only on events, such as individual physician visits or individual hospital discharges. Historical- ly, NCHS has provided basic information for a broad range of issues related to the supply and volume of health care, but has lacked person-based infor- mation on health care received by individuals over time or over the entire progression of an illness episode, from onset to completion. However, policy analysts and other data users also need data on persons and about the medical care received by them in order to answer questions about episodes of illness, outcomes, costs and expenditures for care, insurance coverage, the use of multiple providers, etc. The person-based longitudinal approach would also allow for linkage to the death record through the National Death Index (NDI)2 to obtain the mortality status of those persons being followed longitudinally. Linkage with birth records will be needed in pregnancy related to outcome studies. The cost of health care is one of the most important health policy issues confronting the nation today. Although the NCHS statutory mandate ~n- cludes monitoring health care costs and financing, including trends in health care prices and costs, the sources of payment for health services, and the federal, state, and local government expenditures for health services, it col- lects almost no information on payers or costs and expenditures for care (including the component paid by insurance) in a survey of health care use 2The National Death Index is a central computerized file of death record information for all deaths in the United States. It is compiled from magnetic tapes submitted to the NCHS by the state vital statistics offices. These tapes, beginning with deaths occurring in 1979, contain a standard set of identifying information for each decedent for use in searches of the NDI file to identify and locate state death records. The NDI is used by researchers conducting prospective and retrospective studies to determine if persons in their studies may have died.
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so TOWARD A NATIONAL HEALTH CARE SURVEY (see Appendix D). The panel recognizes the difficulties in obtaining this information, but it firmly believes that a National Health Care Survey is a logical vehicle to collect data on costs and expenditures of care. The NHDS collects information on discharges, not individuals, so data on readmissions are not available. In addition, information on the function- al status of individuals would make the information on hospitalization more valuable; at the present time there is nothing on functional status in hospital discharge abstracts. The panel recognizes that the feasibility issues with respect to measuring functional status of hospitalized patients are numer- ous, but, if they could be overcome, research on outcomes of hospital care would be greatly strengthened. This need for more information on health and functional status of the patient for the purpose of evaluating outcomes extends, of course, to all provider sites and should be recognized in all the provider surveys. Information on the longitudinal dimensions of care is of critical impor- tance in order to assess the effect of treatment. Current data sets do not permit construction of meaningful patterns of care over time. This has been particularly problemat ^n long-term care, although there have been notable efforts to begin to correct this problem in the most recent National Nursing Home Survey. The panel is encouraged to note that some of the needed information on the residents will be available from the follow-up study to the 1985 National Nursing Home Survey. However, there is no indication in the center's plan that collection of such information will continue as part of the long-term care component of the proposed new survey. There is need to link multiple admissic*~;` of individuals rather than treat- ing each admission as a new patient, as is cure^-itly the case in NHOS, NAMCS, and NNHS. Such linkage would especially enhance the value of the National Nursing, Home Survey. Almost one-third of all nursing home discharges are to hospitals (NCHS, 1981~. Estimates suggest that one in five nursing home residents has a hospital admission each year. Research suggests that inappro- priate use of the hospital by nursing home residents is a significant hidden cost of long-term care and amounts to cost shifting in a substantial proportion of cases from Medicaid to Medicare, with possible adverse health outcomes for patients (Aiken, et al., 1985; Shaughnessy,l990~. Yet it has not been possi- ble to study the patterns of care and interchange of patients between hospi- tals and nursing homes from the current NCHS data sets. To be maximally useful, existing provider surveys do not include suffi- cient data on characteristics of providers and their practice patterns. A valuable addition would be to increase the amount of information about the various facilities, settings, and providers in which sampled events occur. For the hospitalization component, data should be collected about corporate structure, and other related variables of short-term hospitals should be add- ed from the American Hospitalization Association's files. For ambulatory
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REVIEW OF THE NCHS PLAN 51 care in private offices, the kind of corporate arrangement in which physi- cians are practicing, the mix of specialties, the number of physicians in- volved in a group (if it is a group), and relationships to managed insurers constitute information that would be useful in tracking what is happening to ambulatory care. In recent years there has been major growth in specialized units in general hospitals such as specialized psychiatric units, alcohol treatment units, and drug detoxification and treatment units. Patients treated in these units are different from those treated in "scatter" beds, and patterns of service, length of stay, and costs differ for patients in these units compared with patients with comparable diagnoses treated in general medical units. NCHS needs to develop plans to obtain information on patients seen in such special units of general hospitals. This deficiency is easily corrected by a simple coding change to indicate whether the patient was treated in a spe- cialized unit. An important new data collection activity that NCHS should explore is the addition of data from medical records or charts to the content of the National Health Care Survey. As mentioned previously, a major limitation, not only of NCHS surveys, but also of virtually all data sets about health care services, is the lack of detailed information on the tests and services performed during the various treatment events. The addition of such data from medical records or charts to the content of the surveys is critical to at least three important areas of research: (1) studies related to the appropri- ateness of care, (2) studies of outcomes and efficacy of treatments, and (3) studies of costs of treatment. As a first step, a sample of charts from hospital discharges and from ambulatory care visits should be drawn. The information to be abstracted from these charts should be able to address issues such as: . What tests were performed. Details on how patients were treated. This information is critical to outcome studies to evaluate the efficacy of alternative ways of treating patients. Details about treatments are also essential for evaluating information about the cost of care and for producing comprehen- sive statistics on health care use. In particular, insurance claims do not have information about noncovered services. For example, the administrative system of Medicare does not provide information about the use of prescription drugs. Moreover, providers outside the traditional fee-for-service system, such as health maintenance organizations (HMOs), typically do not file insurance claims in detail. As a result, in order to get any information about the value of delivered care, it is necessary to collect the detail that appears only on hospital and medical charts.
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52 TOWARD A NATIONAL HEALTH CARE SURVEY NCHS will play a major role in the years to come in monitoring the progress of the department's Health Objectives for the Year 2000 (IJ.S. DHHS, 1991a). NCHS has responsibility for tracking about 160 of more than 300 objectives. Although most of these objectives involve promotion of healthful behaviors in the population, rather than health systems perfor- mance per se, 28 specific objectives do relate to health care. Although NCHS is not currently collecting the needed information, the panel is in- formed that 20 of these objectives could be addressed by adding questions about physician practices to the physicians induction questionnaire for the National Ambulatory Medical Care Survey in order to assess patient treat- ment and health promotion activities. NCNS should start collection of the additional information beginning with the next cycle of the National Ambulatory Medical Care Survey so that baseline data will be available to measure progress toward the depart- merzt's Health Objectives for the Year 2000. The content areas identified above are needed now and will continue to be needed in the foreseeable future, for policy analysis of the critical health care issues both for the 1990s and into the next century. It is essential therefore that NCHS move boldly into new areas of data collection and new methods that are required to obtain the needed data to meet the challenges of the next century. Recommendation 3-4: The panel recommends that `~e National Health Care Survey include collection of person-based longitu- dinal information, expanding the data collected to include, but not be limited to, information on the health care received, costs and gross expenditures for health care, and outcomes. DESIGN FEATURES Cluster Survey Design A central feature of the center's plan for the National Health Care Survey is to move from the existing four independently designed provider surveys to a three-stage cluster sample designs and to link the sample selec- tion of these surveys geographically with the sampling design of the Na- tional Health Interview Survey (NHIS). Under this design the health care providers are to be sampled at the second stage from a first-sta~e sample of geographic areas, rather than selecting, the providers at the first stage. The geographic areas currently being used for fielding the new survey are a 3Cluster sampling, frequently used by statisticians in designing surveys, is a method of sampling in which a population is first defined as groups or clusters of primary units and then from these groups a sample is selected.
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REVIEW OF THE NCHS PLAN 53 subsample of the primary sampling units for the NHIS. This linkage with NHIS is consistent with the center's decision to base the NCHS Integrated Design Program on the NHIS sample and to establish survey linkages to the other NCHS population surveys (see Appendix A). Other features being considered by NCHS include the possible use of the same samples of health care providers over time and for several components of the National Health Care Survey in order to increase data quality and to reduce sample induc- tior~ costs. The center has identified in its plan several potential advantages: (1) in- creased analytic utility, since health care use is examined in relation to health status indicators from the NHIS; (2) reduced interviewing costs, since sample providers are concentrated in specific geographic areas; (3) increased potential for record linkage across settings, which aids in tracking patients and in differentiating multiple episodes of the same condition; and (4) the possibil- ity of producing local area statistics, for sampled areas or communities. The stated advantages of moving to a cluster sample design are being examined by NCHS. Research is currently under way for the next cycle of the NHIS redesign based on the 1990 census, including not only issues related to the NCHS population surveys, but also particular requirements of the NCHS provider surveys. Factors related to subdomain statistics, alter- native design options, including the redefinition of PSUs in terms of health service areas, the effect of conducting the National Health Care Survey components in a subsample of the NHIS PSUs, and the analytical utility of such a design are being explored as part of the redesign effort. Results of this research are beginning to be available to NCHS. In reviewing the center's proposed survey design, it becomes clear that there are two related but distinct aspects to the issue of the use of geograph- ic areas as the primary sampling units in the cluster survey design: (1) the use of NHIS PSUs and (2) the definition of PSUs, i.e., current NHIS PSUs that are population based or PSUs defined in terms of health service areas. Use of NHIS Primary Sampling Units The panel believes that there may be some practical advantages to hav- ing, the National Health Care Survey and the NHIS conducted in the same PSUs. It is possible that there will be efficiencies in sharing data collection staff (trained Census Bureau field staff), although the real benefits cannot be assessed until the actual strategies for data collection are fully in place. Furthermore, the assumed cost savings of having the providers geographi- cally clustered needs to be demonstrated. The trade-off between reduced costs through use of a clustered provider sample and the impact of this design on the efficiency of the sample needs to be examined further. NCHS staff estimates suggest that, for national estimates, the loss of efficiency
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54 TOWARD A NATIONAL HEALTH CARE SURVEY will be modest, less than 6 percent for the NHDS (Shimizu and Cole, 1990~. The panel is not aware of similar research for the NAMCS but would be surprised if the results were worse, given the apparent correlation between physician and population geographic distributions. The panel seriously doubts the possibility of producing local area estimates by conducting the survey in a subsample of the NfITS PSUs, even with the planned multiyear aggrega- tion of data. As stated earlier in the chapter, given the current sample sizes, the panel questions if NCHS will be able to produce reliable estimates for states, let alone for specific PSUs. NCHS obviously has given considerable thought to the concept of an integrated National Health Care Survey and has presented arguments that its plan implies integration. The panel supports the use of the NHIS PSUs as an important first step in that direction. It should be emphasized, however, that simply conducting the provider surveys in the NHIS PSUs does not by itself result in a meaningfully integrated survey. There are a number of approaches that, taken together, would achieve greater integration with the NHIS than envisioned in the center's plan. Within the context of this survey, the panel believes that a National Health Care Survey would be considered integrated if it had the capability of obtaining relevant health care data at the person, provider, visit, or episode level that can be inter- linked directly at the individual rather than at the aggregate level. Thus for example, behavioral and health status data for a sample person can be tied to such things as the use of health care facilities, the care received, the costs, and the outcome of health care received for the illness episodes that the person is experiencing. Definition of Primary Sampling Units The panel is skeptical about the assumption of increased analytic utility resulting from geographic linkage and by defining the PSUs in teas of health service areas. NCHS defines health service areas as one or more counties that are relatively self-contained with respect to the provision of routine hospital care. NCHS plans to be able to examine health care use in a geographic area in relation to the availability of health resources and the health status indicators from the NHIS. This would permit the computation of ecological correlations using the health service area as the unit of analy- sis. Recent research by Makuc and others on defining health service areas showed that, in a group of health service areas representing roughly 94 percent of the U.S. population, less than 25 percent of the hospital stays of people residing in those areas occulted outside the service area (Makuc et al., 1990~. When examining patterns for ambulatory care, Kleinman and Makuc found that nearly 20 percent of physician visits occur outside the county of residence, with substantial variation according to metropolitan
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REVIEW OF THE NCHS PLAN 55 status., proximity to the metropolitan area, and population density (Klein- man and Makuc, 1983~. No parallel research has been completed for nurs- ing homes. Makuc presents some examples of the kinds of analyses that could be undertaken based on the first-stage area design. Each area can be character- ized by census variables and variables from other sources, such as the Area Resource File.4 Health care data can be produced for the same areas so that such questions as the following could be answered: to what extent is one subcomponent of care being substituted for another, e.g., ambulatory surgi- cal centers as a substitute for inpatient hospital care, hospice and home care for nursing home care? To what extent can variation in rates of utilization of health care be explained by variation in supply of providers? Small area variation in the use of health services might be used to monitor the effec- tiveness of the medical outcome initiatives. There are several issues that need further research before the utility of this kind of analysis can be deter- mined. One example is the use of self-representing and non-self-represent- ing PSUsi in the current National Health Interview Survey design. Even if all the issues can be resolved, a major problem would still remain: the use of ecological correlations to draw inferences about rela- tionships that refer to individuals. The PSUs defined in terms of health service areas may contain too diverse a population to permit valid charac- terization by some of the kinds of variables listed above. The internal variation may simply be too large. However, individual-level analysis can also be done by linking information about the individual health service area to the individual's health information. In an attempt to resolve some of the issues identified above, research was undertaken by both the NCHS and the Bureau of the Census, as part of the overall NHIS redesign research, to attempt to define health service areas that would maximize the proportion of individuals receiving, their health care within the defined areas, as well as to measure the effects of using these areas as PSUs on the precision of the survey estimates. The panel has learned that, on the basis of the findings of this research, NCHS has made the design decision to retain for the 1995 NHIS redesign the existing defini- 4The Area Resource File is a county-level health resources database containing over 7,000 health professions and related data elements for each county in the United States. The purpose of the file is to summarize statistics from many disparate sources into a single file in order to facilitate analysis and planning of the geographical distribution of health professionals and health resources. The Area Resource File contains data on geographic descriptor codes and classifications, health professions, health characteristics and economic data, expenditures, and environment. The data are drawn from major national surveys completed by numerous federal agencies and professional associations. HA self-representing primary sampling unit is one that is included in the sample with certainty.
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56 TOWARD A NATIONAL HEALTH CARE SURVEY talon of PSUs. There is also some concern that defining PSUs in terms of health service areas increases the NHIS sampling errors, the design effects being, somewhat larger for the Hispanic population. Another factor influ- encing the decision is the fact that the health service areas cross state boundaries, thus making the NHIS redesign less appropriate for producing state statis- tics. Analytic justifications for changing the PSU definition are lacking at this time. This decision does not preclude consideration of redefining the PSUs for the next NHIS redesign; in the interim, however, more research needs to be undertaken before the next NHIS redesign to determine the analytic gains, if any, and the cost consequences of redefining the NHIS PSUs. In summary, the concept of defining a geographic area in which most of the providers serving a population are located and most of the population receiving services from the providers in that area are also located is appeal- ing. However, there are major difficulties in defining a health service area across a range of services and different types of providers. For example, the seNice areas for treatment of rare or serious conditions may not coin- cide with the service areas for primary care. Moreover, there appears to be serious loss in efficiency in using these areas as PSUs in the sample design. The panel has not seen any definitive evidence at this time of the feasibility or analytic justification of redefining the PSUs in terms of health service areas on a national level, particularly since the health service areas can be used in analyses of NCHS surveys without using them to define PSUs. The panel, however, supports the center's intention to continue the needed re- search in this area. Recommendation 3-5: The panel endorses the NCHS decision to use the primary sampling units from the National Health Interview Survey for the National Health Care Survey, to re- tain their existing definition at this time, and to continue the needed research in this area. Patient Follow-up Component The center's plan for the National Health Care Survey includes devel- opment of the capability to conduct routine and specialized patient follow- up studies of the sample event (visit, discharge, or admission) to obtain information beyond what is available in provider records. Data will be collected from the patient or the patient's family about the patient outcome, including subsequent use of medical care and morbidity, changes in health status, and quality of care. The development of the follow-up component will build on the experience gained from the 1985 National Nursing, Home Survey Follow-up and the various follow-up studies of their population-based
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REVIEW OF THE NCHS PLAN . . . . 57 surveys. NCHS also anticipates linking these data with other data sources, just as the National Nursing Home Survey is being linked to the National Death Index to obtain mortality status information on former patients. Discussed below are some of the potential values of the design involv- ing follow-up of patients whose visits and discharges are sampled for the provider surveys; some of the methodological, legal, and feasibility issues that will need to be resolved before such studies can be undertaken; and the limitations of such an event-based approach to obtain the kinds of health care data needed. There are a number of potential benefits of the planned follow-up com- ponent to the National Health Care Survey: Data could be collected in the follow-up component to enable pa- tients to be characterized in terms of their health status, demographic characteristics, health behaviors, and other use of medical care. Data could be collected from the patient or the patient's family over a period of time about the results of treatment for the sampled event, including use of medical care and morbidity subsequent to the sampled event, changes in health status, hospital readmissions, and quality of care. A patient follow-up study could be conducted to focus on specific issues such as a financing mechanism; particular demographic or other groups of interest; a particular disposition at discharge; a diagnosis, condition, or procedure; or any emerging issue. Follow-up interviews with patients open the possibility of collect- ing meaningful data on gross expenditures from providers of the medical care and from insurers who paid for the service, at least for the specific sampled event. Patterns of care could be described for at least a subset of health care events, which could enhance the analytic value of the data about those services provided. An important current concern in health policy research is the evaluation of the effect of various patterns of treatment and medical care on patient well-being. To address such issues, it is necessary to collect data directly from patients about their health status, symptoms, and quality of life at one or more points after they have received health care services and treatments. Once a mechanism is in place for contacting patients who are sampled in ambulatory or hospital settings; it would become possible to initiate special studies of the results of those treatments and the medical outcomes associat- ed with those sampled events.
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58 Unresolved Issues TOWARD A NATIONAL HEALTH CARE SURVEY One of the problems inherent in the event-based follow-up design is the need to get consent from patients for their health provider to release to NCHS the name and address information needed in order to approach the individual patients selected for follow-up. For patients whose visits were sampled in an ambulatory setting, two alternative designs present them- selves: (1) ambulatory care providers could be asked ex post facto to con- tact the sample patients to gain permission for subsequent follow-up or to allow for their patients to be contacted directly for follow-up and (2) inter- viewers could interact with the patient directly in the physician's office. The latter approach is similar to the design used in the Medical Outcome Study (Tarlov et al., 1989~. In that project, an interviewer was continually present in the physician's office during the sampling period. The interview- er can explain the study, obtain needed release permissions, obtain informa- tion needed for subsequent contact, and obtain data from patients. Al- though this procedure would obviously require feasibility testing, and certainly would constitute a major change in current survey procedures, the fact that such a design has been used by others makes it worth serious consideration. The feasibility, costs, and effectiveness of each of these procedures would need to be investigated. A field study of the cost and effectiveness of these approaches might also be considered in conjunction with any study to test feasibility of alternative procedures to obtain names and addresses of sam- pled patients. Similar types of issues must be addressed for a sample of discharged patients who were in the hospitalization survey sample. Permission will be needed also from the hospital administrator to release to NCHS information about the hospitalized patient, either at the time of admission or after the discharge. One approach that can be considered is to have sampled hospi- tals routinely ask for a release from all patients upon admission during a sample period. An alternative approach is a passive consent procedure whereby hospitals would mail to the discharged patients notification that their names (nothing about their conditions) would be transmitted to NCHS unless patients request that they not be. Matching the patient rec' -; s to interview responses would occur only after patients had been informed and had signed a consent form for the interviewer. Both approaches would require considerable effort on the part of hospital employees. The feasibil- ity and acceptability to hospitals and patients of alternative ways to gain patient consent for follow-up need to be explored and tested. Moreover, state laws vary widely on release of information on hospitalized patients. In addition to the issues identified above, there are several other meth- odological issues that need to be addressed to assess the feasibility of the event-based follow-llp design, such as the efficacy of alternative ways to
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REVIEW OF THE NCHS PLAN 59 deal with the problem of linkage between providers, visits, and persons; the extent of attrition occurring during the process of contacting patients for follow-up through the provider setting in which they were identified (i.e., hospital or ambulatory care provider); and the problem of constructing sam- pling frames for providers other than those covered by existing surveys in order to conduct the follow-up studies as planned by NCHS. Research needs to be undertaken to evaluate the feasibility and effec- tiveness of each of these issues and procedures, including an examination of the literature to assess how effective these procedures have been when used in previous studies. Limitation of Event-based Follow-up Design Although the panel supports the center's desire to develop capability for collecting data directly from patients through follow-up, a key issue in the design suggested in the plan is the appropriateness of an event-based sample for follow-up studies. A major limitation of the National Health Care Survey as presently designed is that all the provider surveys begin with a sample of events and not persons. That means that the probability of selection of any individual patient depends on the number and type of eligible services that he or she receives. In the ambulatory care component of the survey, for instance, people are sampled proportionate to their use of ambulatory services in physicians' offices. Although Hat may be a s~ghdorward way to sample events, it is not an efficient design for producing person- based statistics. Many health conditions produce multiple visits to an am- bulatory care setting; NCHS needs to determine the extent of the confound- ing problem resulting from the use of an event-based survey. The conceptual development of the issues involved in samples of events versus persons as a unit of analysis has lagged; there is a clear need to think about these issues in a more concrete and systematic manner than is possible within the con- straints of this study. Laumann and Knoke (1987), for example, devote an extended theoretical discussion in their book The Organizational State to the actor-event interface and the analytic and methodological problems en- gendered by taking the focal analytic unit to be the actor or the event, and the need to see that these analytic units are, in fact, intimately interrelated in myriad ways. Their perspective is especially congenial to researchers who have adopted network-related analytic techniques. Analyses of costs and outcomes depend on identifying meaningful clin- ical events. Some service events are meaningful units to sample. The best examples are those surgical procedures that almost always occur in hospital settings and that usually occur only once to an individual. For example, sampling hospital discharge records is a meaningful way to sample people who experience gall bladder surgery or appendectomy. Starting with such a
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60 TOWARD A NATIONAL HEALTH CARE SURVEY sample, one could collect data about related services and interview patients at a later date about the complications and benefits of surgery. All hospital- izations, however, do not always produce meaningful data. For example, hospital admissions for cancer could serve as a sampling frame to describe the characteristics of those hospitalized for cancer and the services that they utilize, their costs, and how they were feeling at some later point. Howev- er, the same case of cancer could produce multiple admissions, and for some analytic purposes the omission of those who had cancer but were not hospitalized at the time (and hence were not represented in the statistics) could constitute a serious problem. In summary, the follow-up design described by NCHS potentially adds to the value of the data collected from the NHDS and the NAMCS for studying certain conditions. NClIS has made a case for sampling clinically meaningful events from provider-based samples. Treatments that usually occur only once constitute one class of health care that can be studied from such samples. Health conditions that almost invariably lead an individual to seek care from a provider, such as a broken hip, a broken leg, or a heart attack, also probably can be meaningfully sampled from event-based sample frames. There are real practical problems, however, associated with obtain- ing permission and contacting a high percentage of sampled patients. There are multiplicity problems associated with sampling to be resolved, arising from the fact that an individual's chance of selection depends on the num- ber of health care events the individual had for the condition (Sirken, 1972a, 1972b; Nathan, 1976~. CONCLUSION The panel supports the center's primary objective for the National Health Care Survey. The panel is concerned, however, that, as currently designed, the survey appears to be limited mostly to modest modifications and cover- age extensions of the existing provider-based surveys, with minimal, if any, true integration of design and data. Yet the concept of a National Health Care Survey is a broad and challenging concept. If the center's objective, as stated in its plan, is to move in the direction of an integrated survey design to provide comprehensive health care data that are urgently needed, especially on access, expenditures, disease episodes, and outcomes, then such an objective should have a major impact on the design and content of their surveys. NCHS cannot get that kind of statistical information from a sample of events, which is its current approach. Although NCHS provider surveys have considerable strengths in mea- suring the health services provided in traditional medical care settings and in some alternative care settings in the near future, they reflect only part of the care provided in the United States today. Each of the NCHS provider
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REVIEW OF THE NCHS PLAN 61 surveys on health care is oriented toward providing data on services re- ceived for the sampled event in the respective facility. When taken togeth- er, they do not represent a comprehensive approach to the collection of the needed data on the nation's health care system. NCHS has proposed strategies to address some of the gaps in the data from its existing provider-based surveys. The panel supports these initia- tives; however, the panel believes that the center's vision for a National Health Care Survey falls short of a plan for meeting anticipated health care information needs today and into the next century, even with the sugges- tions contained in this chapter for changes and improvements. The panel strongly urges the center to become more comprehensive in its approach to meeting the data needs identified in this report. A strategy that is flexible enough to adapt to changes and new fast-breaking directions requires a more integrated and a more visionary course of action than currently planned by NCHS. The next chapter provides the panel's recommendations for a design framework that would lead to a more integrated National Health Care Data System that will provide the basis for such a flexible, long-term data collection and implementation strategy.
Representative terms from entire chapter: