County as a Fundamental Unit of Analysis of Health Insurance Coverage in the United States

As the debate about health care reform continues, counties remain an important locus of access and barriers to access for the uninsured, the underinsured, and those covered under medically indigent adult programs. National- and state-level proposals for improving health equity rarely consider current policies and potential interventions at the county level. This study examined inter-county variability in insurance coverage, as well as county characteristics as predictors of uninsurance. We merged and analyzed data for 3,079 counties from public use data sets (Area Resource File, USA Counties, and the Small Area Health Insurance Estimates program). Multiple regression analysis, including semi-partial correlation coefficients, assessed the relative importance of local structural capacities (tax base, income, and health professional availability), political ideology (votes cast for President by political party), and county demographic characteristics in predicting health insurance coverage. We found major inter-county variability in uninsurance ranging from 4% to 38%, a much wider range than revealed by state-level aggregated data. In the multiple regression analysis, variables strongly predicting county-level uninsurance rates included percentage of persons living in poverty, percentage Hispanic, and percentage voting Republican. County-level regression analysis was able to explain 84% of the variance in uninsurance rates.

Findings from our study provide insights for public health leaders, researchers, and policy makers on the extent of inequities in access to health care and potential solutions for improving coverage. As one example, our findings show that the problem of uninsurance is highly concentrated in a limited number of counties throughout the country. In contrast, some counties are capable of mobilizing local leadership and resources to support policy changes that enhance access. The responsibility for financing, delivery, and regulation of health care in the United States is shared jointly among federal, tribal, state, and county governments. Although this inter-governmental authority has comprised a cornerstone of our nation's health care safety net, the details of these relationships remain surprisingly varied. Strategies for achieving health care reform should embrace inter-governmental solutions that consider the role of counties in providing health and public health services, increasing insurance coverage, and leveraging resources to assure adequate local infrastructure for delivery of services at the county level.