Comparing oral health care utilization estimates in the United States across three nationally representative surveys

Health Services Research, April, 2002 by Mark D. Macek, Richard J. Manski, Clemencia M. Vargas, John F. Moeller

The nation requires valid and reliable estimates of the proportion of the population with a dental visit each year for a variety of important purposes. For example, public health practitioners and legislators rely on these data to develop policy concerning access to care and the financing of oral health services. Policymakers also use these data to identify barriers to oral health care for specific populations subgroups and to create programs that eliminate obstacles to oral health care. Researchers use dental visit data to assess trends over time and to evaluate changes resulting from the implementation of health programs. Finally, federal agencies use these utilization estimates to track progress toward national health objectives (Health People Objectives) (U.S. Department of Health and Human Services 1997).

There are three main sources of nationally representative dental visit data in the United States. These sources include the National Health Interview Survey (NHIS), National Health and Nutrition Examination Survey (NHANES), and health expenditure surveys (1977 National Medical Care Expenditure Survey [NMCES], 1987 National Medical Expenditure Survey [NMES], and 1996 Medical Expenditure Panel Survey [MEPS]). The National Center for Health Statistics (NCHS) of the Centers for Disease Control and Prevention conducts the NHIS and NHANES, and the Agency for Healthcare Research and Quality, formerly the Agency for Health Care Policy and Research, administers the health expenditure surveys.

The NHIS has long been the standard data source in the United States for dental visit information. For example, public health professionals used dental visit data from the NHIS for baseline and periodic national health objective assessments during the 1980s and 1990s. In more recent years, the relative ease with which researchers have had access to NHANES and health expenditure survey data suggests that surveys other than the NHIS might be relied on to provide dental visit estimates in the future. Although one might hypothesize that the dental visit estimates derived from the NHANES and health expenditure surveys should be comparable to those derived from the NHIS, this hypothesis has remained untested.

The purpose of this investigation was to compare dental visit estimates derived from the standard NHIS with estimates derived from NHANES and the health expenditure surveys. We assessed differences on two levels: (1) overall estimates across surveys and (2) stratum-specific trends within surveys. This investigation is important because it addresses whether, and to what extent, NHANES and the health expenditure surveys differ from the standard NHIS and places the differences in the context of relevant political, public health, and research issues.

MATERIALS AND METHODS

Selection of Surveys and Survey Years

This manuscript contains data derived from several surveys, including the 1986 NHIS, 1989 NHIS, and 1993 NHIS; NHANES I (conducted between 1971 and 1975) and NI-LANES III (conducted between 1988 and 1994); and 1977 NMCES, 1987 NMES, and 1996 MEPS health expenditure surveys. We selected these surveys because they were representative of the U.S. population, they served as common references for dental visits, and they were administered by more than one federal agency. We selected several survey years from within each data source in order to assess the stability of estimates over time.

NHIS

The objective of the NI-US is to assess timely health issues through the collection and analysis of data related to (1) health and illness status, (2) general health attitudes, behaviors, and knowledge, and (3) health care utilization (Massey et al. 1989). The NHIS is the largest source of such self-reported data for the civilian, noninstitutionalized household population of the United States. Prior to a survey redesign in 1997, the NHIS questionnaire consisted of two parts: a set of basic health and demographic items contained within a core component and one or more sets of questions on current health topics contained within a supplement component. Questions contained within the supplement component change from year to year in response to current interest and need for data (Massey et al. 1989). The NHIS frequently includes an oral health supplement that contains questions regarding oral health care utilization. An advantage of the NHIS is that it uniquely allows analysis of the associations between oral heal th care utilization and a variety of health and illness status items, as well as health attitudes, behaviors, and knowledge.

The NHIS has included questionnaire items concerning dental visits and utilization on and off since the late 1950s. For the purposes of this investigation, we selected three of the most currently available NHIS instruments: the 1986 NHIS, the 1989 NHIS, and the 1993 NHIS. The 1986 NHIS contained a Dental Health Supplement questionnaire that assessed utilization of oral health care services using several reference periods, including 2 weeks, 12 months, and 5 years or beyond (Jack and Bloom 1988). The supplement was administered to half of the total NHIS sample (n 62,052 persons) (Jack and Bloom 1988). Only survey participants 2 years of age or older were eligible for the dental visit questions, and the survey allowed proxy respondents to answer the utilization items for those unable to respond for themselves.