Implications of the Medicaid undercount in a high-penetration Medicaid state

This study investigates the impact of misreporting by Medicaid recipients on estimates of the uninsured in Louisiana, and is based on similar work by Call et al. in Minnesota and Klerman, Ringel, and Roth in California. With its unique charity hospital system, culture, and high poverty, Louisiana provides an interesting and unique context for examining Medicaid underreporting.

Results are based on a random sample of 2,985 Medicaid households. Respondents received a standard questionnaire to identify health insurance status, and individual records were matched to Medicaid enrollment data to identify misreporting.

Data were collected by the Public Policy Research Lab at Louisiana State University using computer-assisted telephone interviewing. Using Medicaid enrollment data to obtain contact information, the Louisiana Health Insurance Survey was administered to 2,985 households containing Medicaid recipients. Matching responses on individuals from these households to Medicaid enrollment data yielded responses for 3,199 individuals.

Results suggest relatively high rates of underreporting among Medicaid recipients in Louisiana for both children and adults. Given the very high proportion of Medicaid recipients in the population, this may translate up to a 3 percent bias in estimates of uninsured populations.

Medicaid bias may be particularly pronounced in areas with high Medicaid enrollments. Misreporting rates and thus the bias in estimates of the uninsured may differ across areas of the United States with important consequences for Medicaid funding.