Health care markets, the safety net, and utilization of care among the uninsured

Health Services Research, Feb, 2007 by Carole Roan Gresenz, Jeannette Rogowski, Jose J. Escarce

DATA AND METHODS

Data

We use data from the MEPS household component (HC) survey linked to data from numerous sources describing the safety net and health care market structure. The MEPS HC is a nationally representative survey with detailed information on health status and health services utilization. MEPS uses an overlapping panel design in which respondents are interviewed multiple times over a 30-month period to collect data spanning a 2-year period (Cohen et al. 1996/97).

To describe the health care safety net and market structure in each individual's location, we derived variables from numerous sources including the American Hospital Association (AHA) Annual Survey of Hospitals, Area Resource File (ARF), the InterStudy Regional Market Analysis database, the Bureau of Primary Healthcare (BPHC) Uniform Data System, the Current Population Survey (CPS), the Census of Governments, and the Census Bureau's Annual Survey of State and Local Government Finances. Because the public use MEPS data do not contain geographic identifiers, variables describing the health care market and safety net were linked to MEPS respondents by Social and Scientific Systems (SSS), operating through a contract with the Agency for Healthcare Research and Quality (AHRQ). The resulting data file, stripped of geographic identifiers, was available for our use on-site at the AHRQ Data Center.

Study Sample

Our analysis pools MEPS respondents who were uninsured for at least one full calendar year during the period from 1996 to 2000. Each observation represents a 1-year period of an individual being uninsured; thus, there are two observations for each respondent who was uninsured during both calendar years in which he/she was surveyed. We focus on the adult uninsured population (patterns of health services utilization, types of chronic health conditions, and health insurance availability all differ markedly for children compared with adults) and exclude from analysis respondents under the age of 18 or aged 65 or older, as well as individuals who were ineligible for all or part of the calendar year (such as those who died or were institutionalized during the year). In total, our data include 12,513 observations of full calendar-year episodes of uninsurance from 8,285 respondents. There are roughly 2,000-3,000 observations from each year. All analyses are run separately for individuals living in metropolitan statistical areas (MSAs) and non-MSAs. We term the former "urban" uninsured and the latter "rural" uninsured.

Dependent Variables

We focus our analysis on outpatient measures of utilization, including number of office-based physician visits, number of office-based nonphysician visits, and number of emergency department (ED) visits. Office-based visits include visits to physicians' private offices, to outpatient clinics associated with hospitals, and to community health centers; they do not include outpatient department hospital services. We also analyze whether the individual has had any medical expenditures or charges (exclusive of dental and vision), which provides an overall measure of individuals' access to the health care system. The variable is positive if an individual has any expenditures for inpatient or outpatient care, pharmaceuticals, durable medical equipment, or other types of care (e.g., home health). In addition, the variable is positive if an individual had no expenditures but had positive charges, which indicates receipt of charity (free) care. Table 1 provides descriptive statistics for the dependent variables.