OBJECTIVES: We examine whether the expansion of Medicaid coverage has resulted in a decrease in the rate of emergency department (ED) visits within socially deprived counties.

METHODS: For this retrospective analysis, we used the Arizona State Emergency Department Database obtained from the Healthcare Cost and Utilization Project for 2010 through 2019. We further used the updated version of the New York University Emergency Room algorithm to identify visits defined as nonemergent and emergent. We conducted interrupted time-series analysis at the county level and limited the study to individuals aged 18-64, resident in Arizona, who had outpatient ED visits and who were either Medicaid-enrolled or uninsured within counties with more than 500 ED visits.

RESULTS: The regression analysis on the combined uninsured and Medicaid population did not show any statistically significant changes for the overall rate of ED visits. The results show that in counties with high deprivation the total rate of all uninsured ED visits in 2013 was about 35 visits per 1000. In 2014, a statistically significant 18-point drop was observed in the rate of uninsured ED visits (P<0.0001; CI= -25.44, -12.00). The findings for emergent visits among uninsured showed a drop of 3.2 (P<0.0001, CI= -4.23, -2.10) points in 2014 and a 1.20-point decrease in the subsequent years. Additional findings for non-emergent visits among uninsured indicated an 8.87-point drop (P<0.0001, CI= -12.59, -5.10) in 2014. Analysis of Medicaid-enrolled patients showed statistically significant increases in rates of ED visits.

CONCLUSIONS: While rates of ED visits declined significantly among the uninsured for emergent and non-emergent reasons, the rates of ED visits increased among the Medicaid-enrolled, indicating that there was a shift in the proportion of the uninsured who were newly Medicaid-rolled during the study period and not necessarily a reduction in overall ED visits among patients from socially deprived counties in Arizona.