The Effect of Medicare Shared Savings Program on Readmissions and Variations by Race/Ethnicity and Payer Status (December 9, 2020)

OBJECTIVE: Accountable care organizations in the Medicare Shared Savings Program (MSSP) in the United States attempt to reduce cost and improve quality for their patients by improving care coordination across care settings. We examined the impact of hospital participation in the MSSP on 30-day readmissions for several groups of Medicare inpatients, and by race/ethnicity and payer status. MAIN DATA SOURCE: A 2010-2016 Medicare Provider Analysis and Review files. RESEARCH DESIGN: With propensity score matched sample of MSSP and non-MSSP-participating hospitals, patient-level linear probability models with difference-in-differences approach were used to compare the changes in readmission rates for Medicare fee-for-service patients initially admitted for ischemic stroke, hip fracture, or total joint arthroplasty in MSSP-participating hospitals with non-MSSP-participating hospitals as well as to compare the changes in disparities in readmission rates over time. PRINCIPAL FINDINGS: Hospital participation in MSSP was associated with further reduced readmission rate by 1.1 percentage points (95% confidence interval: -0.02 to 0.00, P<0.05) and 1.5 percentage points (95% confidence interval: -0.03 to 0.00, P=0.08) for ischemic stroke and hip fracture cohorts, respectively, compared with non-MSSP-participating hospitals, after the third year of hospital participation in the MSSP. There was no evidence that MSSP had an impact on racial/ethnic disparities, but increased disparity by payer status (dual vs. Medicare-only) was observed. These findings together suggest that MSSP accountable care organizations may take at least 3 years to achieve reduced readmissions and may increase disparities by payer status.