The Effect of the Medicaid Expansion on Frequent Emergency Department Use in New York.
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BACKGROUND: There is limited evidence on the effect of the Affordable Care Act (ACA) on frequent emergency department (ED) use. OBJECTIVES: To estimate the effect of the ACA Medicaid expansion on frequent ED use in New York. METHODS: We used data from the Healthcare Cost and Utilization Project State Emergency Department Databases and State Inpatient Databases from 2011 to 2016. A consistent and unique patient identifier enabled us to identify ED visits by the same patient across different facilities within the state for each calendar year. Multivariate logistic regressions were used to quantify the policy's effect on frequent ED use ( 4 ED visits/year). We included in-state residents 18 to 64 years of age who were covered by Medicaid, private insurance, or were uninsured. Sensitivity analyses were conducted using alternative definitions of frequent use. To validate the findings, a falsification analysis was also conducted using only the 3 pre-expansion years. RESULTS: Our study included 14.3 million ED patients with 23.8 million ED visits from 2011 to 2016. Frequent users (7.2%) accounted for 26.6% of all ED visits. The likelihood of frequent ED use declined by 4% among Medicaid beneficiaries (adjusted odds ratio [AOR] 0.96, 95% confidence intervals (CI) 0.95-0.97) and by 12% for the uninsured (AOR 0.88, 95% CI 0.86-0.89) in the post-expansion period, compared with the pre-expansion period. Private insurance enrollees were 9% more likely to exhibit frequent use in the post-expansion period (AOR 1.09, 95% CI 1.08-1.11). The sensitivity analyses yielded results similar to those of the main model. The falsification analyses revealed small and insignificant year-to-year changes in the 3 pre-expansion years. CONCLUSION: The likelihood of frequent ED use decreased 3 years after New York implemented the ACA Medicaid expansion, particularly for Medicaid beneficiaries and the uninsured, highlighting the importance of expanding health insurance and provisions tailored at high-need populations.