Do Changes in Post-acute Care Use at Hospitals Participating in an Accountable Care Organization Spillover to All Medicare Beneficiaries?

BACKGROUND: While early evidence suggests that Medicare accountable care organizations (ACOs) may reduce post-acute care (PAC) utilization for attributed beneficiaries, whether these effects spill over to all beneficiaries admitted to hospitals participating in ACOs stray is unknown.

OBJECTIVE: The objective of this study was to evaluate whether changes in PAC use and Medicare spending spill over to all beneficiaries admitted to hospitals participating in the Medicare Shared Savings Program (MSSP).

DESIGN: Observational study using a difference-in-differences design comparing changes in PAC utilization and spending among beneficiaries admitted to ACO-participating hospitals before and after the start of the ACO contracts, compared to those admitted to non-ACO hospitals.

SETTING: A total of 233 hospitals participate in MSSP ACOs and 3103 non-ACO hospitals.

PARTICIPANTS: A national sample of 11,683,573 Medicare beneficiaries experiencing 26,503,086 hospital admissions from 2010 to 2013.

EXPOSURE: Admission to a hospital participating in an MSSP ACO.

MAIN MEASURES: The probability of discharge and Medicare payments to inpatient rehabilitation facilities (IRF), skilled nursing facilities (SNF), and home health agencies (HHA).

KEY RESULTS: For beneficiaries admitted to hospitals that joined an ACO, the likelihood of being discharged to PAC did not change after the hospital joined the ACO compared with non-ACO hospitals over the same period (differential change in probability of discharge to any PAC was 0.000 (P = 0.89), SNF was 0.000 (P = 0.73), IRF was 0.000 (P = 0.96), and HHA was 0.001 (P = 0.57)). Payments reduced significantly for PAC overall (- $130.41, P = 0.03), but not for any individual PAC type alone. These results were consistent in samples that were conditional on discharge to any PAC, across conditions with high PAC use nationally, and among ACO-participating hospitals that also had a PAC participant.

CONCLUSIONS: Hospital participation in an ACO did not result in spillovers in PAC utilization or payments to all beneficiaries, even when considering high PAC-use conditions and ACO hospitals that also have an ACO-participating PAC.