Changes in Insurance Coverage and Emergency Surgery Rates Associated with Medicare Eligibility

INTRODUCTION: For millions of Americans with common surgical conditions, lack of health insurance may delay care until their condition requires an emergency operation. However, the direct effects of gaining health insurance on reducing emergency surgery rate have not been well described. METHODS: Using data from the 2010 to 2018 Healthcare Cost and Utilization Project National Inpatient Sample, we identified patients 50 to 80 years of age who underwent colectomy, ventral hernia repair, or abdominal aortic aneurysm repair. Outcomes of interest were uninsured rate and emergency (vs elective) surgery rate. We performed regression discontinuity (RD) analyses using a second order polynomial design to evaluate for changes associated with aging into Medicare eligibility at age 65. Models were adjusted for sex, race/ethnicity, income, rurality, weekend admission, operation, and year. RESULTS: Our weighted sample included 1,974,240 admissions. For patients ages 64 years vs 66 years the unadjusted uninsured rates were 3.8% vs 0.4% and the unadjusted emergency surgery rates were 36.3% vs 33.3% (p < 0.01 for both). On adjusted regression discontinuity analysis, aging into Medicare eligibility was associated with a 3.9 percentage-point drop in the uninsured rate and a corresponding 3.6 percentage-point drop in the emergency surgery rate (Figure; p < 0.01 for both). These findings were robust to alternative specifications of the RD model.CONCLUSION: Increased rate of insured patients was correlated with a subsequent decrease in emergency surgery rate for major abdominal operation. While access to high-quality surgical care is multifaceted, these results suggest that efforts to improve health insurance coverage may reduce rate of potentially preventable emergency surgery.