Health insurance coverage during a 24-month period: a comparison of estimates from two national health surveys

National estimates of the uninsured are available from multiple surveys and differ across surveys. Previous efforts to better understand reasons for differences among these estimates have primarily focused on annual estimates. This study compares national estimates of health insurance coverage over generally comparable 24-month time periods using two integrated Federal health-related surveys, the Medical Expenditure Panel Survey (MEPS) and the National Health Interview Survey (NHIS) for the years 2002–2003 and replicated analyses for 2001–2002. We examine survey participants insurance status in year 1 and year 2 based on the NHIS linked with the MEPS and also for MEPS year 1 and year 2 participants. We also examine characteristics associated with 24-month coverage status. National estimates of the percents continuously insured did not differ significantly between the two data sources. In contrast, the MEPS longitudinal estimate of the percent continuously uninsured was higher than the NHIS-MEPS linked estimate whereas the MEPS longitudinal estimate of the discontinuously insured was lower than that derived from the NHIS-MEPS linked data. Factors that help explain these differences include the non-equivalence of the time periods covered by the data sources, modest differences in the length of time covered by the MEPS and NHIS survey instruments, and length of recall. Regression analyses yielded highly consistent correlates of being continuously uninsured versus continuously insured for both data sources. Regression results for discontinuous versus continuous coverage were also generally similar for both data sources. Gaining a better understanding of the alignment in findings based on alternative data sources that support comparable analyses of health insurance coverage helps policymakers to make the most appropriate use of resultant estimates. The views expressed in this paper are those of the authors and no official endorsement by the Department of Health and Human Services or the Agency for Healthcare Research and Quality or the Centers for Disease Control and Prevention is intended or should be inferred.