Trends in Postacute Care Use and Outcomes After Hip and Knee Replacements in Dual-Eligible Medicare and Medicaid Beneficiaries, 2013-2016

IMPORTANCE: Several Medicare alternative payment models were implemented in recent years, but their implications for socioeconomic gaps in postacute care (PAC) are unknown. OBJECTIVES: To determine the longitudinal trends in PAC use and outcomes after hip and knee replacements and in gaps among 3 groups: Medicare-only patients, dual-eligible patients with full Medicaid benefits, and dual-eligible patients with partial Medicaid benefits. DESIGN, SETTING, AND PARTICIPANTS: A cohort study was conducted of PAC use and outcomes among Medicare fee-for-service patients undergoing hip or knee replacement surgery from January 1, 2013, to December 31, 2016, in approximately 3000 hospitals, using Medicare claims, assessment, hospital, and skilled nursing facility (SNF) files. Statistical analysis was performed from October 1, 2018, to December 17, 2019. MAIN OUTCOMES AND MEASURES: Risk-adjusted differences among dual-eligible groups in institutional PAC use (SNF, inpatient rehabilitation, or long-term hospital care), readmission rate, and payment for readmissions; for patients discharged to a SNF, risk-adjusted differences in SNF quality measured by star ratings, proportion successfully discharged to the community, proportion transitioned to long-stay residence, and SNF length of stay and payments. RESULTS: The sample included 1 302 256 patients (837 256 women [64.3%]; mean [SD] age, 75.4 [7.2] years) who underwent joint replacement. The proportion of patients discharged to institutional PAC and the 30-day and 90-day readmission rates decreased for all 3 groups during the period from 2013 to 2016. In 2013, institutional PAC use was 43.7% (95% CI, 43.5%-43.9%) for Medicare-only patients (n = 1 182 555), 70.1% (95% CI, 69.4%-70.8%; n = 60 461) for dual-eligible patients with full benefits, and 70.3% (95% CI, 69.6%-71.0%; n = 59 240) for dual-eligible patients with partial benefits; in 2016, the rates decreased to 32.5% (95% CI, 32.4%-32.7%) for Medicare-only patients, 62.3% (95% CI, 61.5%-63.0%) for dual-eligible patients with full benefits, and 61.5% (95% CI, 60.7%-62.3%) for dual-eligible patients with partial benefits. Among patients discharged to SNFs, outcomes remained flat over time. For example, the proportion of patients successfully discharged to the community remained at 80.5% (95% CI, 80.4%-80.7%) for Medicare-only patients, 59.8% (95% CI, 59.3%-60.3%) for dual-eligible patients with full benefits, and 50.0% (95% CI, 49.4%-50.5%) for dual-eligible patients with partial benefits. Multivariable analyses with adjustment for patient, hospital (or SNF), and geographical covariates suggested maintained or enlarged gaps in all outcomes. CONCLUSIONS AND RELEVANCE: This study suggests that, during the period from 2013 to 2016, Medicare patients undergoing hip or knee replacement showed reduced institutional PAC use, reduced readmissions, and, among those discharged to SNFs, roughly unchanged outcomes. However, dual-eligible patients, especially those with partial Medicaid benefits, had persistently worse outcomes than Medicare-only patients.