Health insurance status change and emergency department use among US adults.

BACKGROUND: Recent events have increased the instability of health insurance coverage. We compared emergency department (ED) use by newly insured vs continuously insured adults and by newly uninsured vs continuously uninsured adults.
METHODS: We analyzed 159,934 adult respondents to the 2004 through 2009 National Health Interview Survey. Health insurance status was categorized as newly insured (currently insured but lacked health insurance at some point during the prior 12 months) vs continuously insured and as newly uninsured (currently uninsured but had health insurance at some point during the prior 12 months) vs continuously uninsured. We analyzed the number of ED visits during the prior 12 months using multivariable Poisson regression.
RESULTS: Overall, 20.7% of insured adults and 20.0% of uninsured adults had at least 1 ED visit. However, 29.5% of newly insured adults compared with 20.2% of continuously insured adults had at least 1 ED visit. Similarly, 25.7% of newly uninsured adults compared with 18.6% of continuously uninsured adults had at least 1 ED visit. After adjusting for demographics, socioeconomic status, and health status, recent health insurance status change was independently associated with greater ED use for newly insured adults (incidence rate ratio [IRR], 1.32; 95% CI, 1.22-1.42 vs continuously insured adults) and for newly uninsured adults (IRR, 1.39; 95% CI, 1.26-1.54 vs continuously uninsured adults). Among newly insured adults, this association was strongest for Medicaid beneficiaries (IRR, 1.45) but was attenuated for those with private insurance (IRR, 1.24) (P < .001 for interaction).
CONCLUSIONS: Recent changes in health insurance status for newly insured adults and for newly uninsured adults were associated with greater ED use. As policy and economic forces create disruptions in health insurance status, new surges in ED use should be anticipated.