The Affordable Care Act's Medicaid expansion and utilization of discretionary vs. non-discretionary inpatient surgery.

Background: While pre-Affordable Care Act expansions in Medicaid eligibility led to increased utilization of elective inpatient procedures, the impact of the Affordable Care Act on such preference-sensitive procedures (also known as discretionary procedures) versus time-sensitive non-discretionary procedures remains unknown. As such, we performed a hospital-level quasi-experimental evaluation to measure the differential effects of the Affordable Care Act's Medicaid expansion on utilization of discretionary procedures versus non-discretionary procedures.

Methods: The State Inpatient Database (2012-2014) yielded 476 hospitals providing selected discretionary procedures or non-discretionary procedures performed on 288,446 non-elderly, adult patients across 3 expansion states and 2 non-expansion control states. Discretionary procedures included non-emergent total knee and hip arthroplasty, while non-discretionary procedures included nine cancer surgeries. Mixed Poisson interrupted time series analyses were performed to determine the impact of the Affordable Care Act's Medicaid expansion on the number of discretionary procedures versus non-discretionary procedures provided among non-privately insured patients (Medicaid and uninsured patients) and privately insured patients.

Results: Analysis of the number of non-privately insured procedures showed an increase in discretionary procedures of +15.1% (IRR 1.15, 95% CI:1.11-1.19) vs -4.0% (IRR 0.96, 95% CI:0.94-0.99) and non-discretionary procedures of +4.1% (IRR 1.04, 95% CI:1.0-1.1) vs -5.3% (IRR 0.95, 95% CI:0.93-0.97) in expansion states compared to non-expansion states, respectively. Analysis of privately insured procedures showed no statistically meaningful change in discretionary procedures or non-discretionary procedures in either expansion or non-expansion states.

Conclusion: In this multi-state evaluation, the Affordable Care Act's Medicaid expansion preferentially increased utilization of discretionary procedures versus non-discretionary procedures in expansion states compared to non-expansion states among non-privately insured patients. These preliminary findings suggest that increased Medicaid coverage may have contributed to the increased use of inpatient surgery for discretionary procedures.