IMPORTANCE

It is unknown how outcomes are affected when patients receive care under bundled payment and accountable care organization (ACO) programs simultaneously.

OBJECTIVE

To evaluate whether outcomes in the Medicare Bundled Payments for Care Improvement (BPCI) program differed depending on whether patients were attributed to ACOs in the Medicare Shared Savings Program.

DESIGN SETTING AND PARTICIPANTS

This cohort study was conducted using Medicare claims data from January 1, 2011, to September 30, 2016, and difference-in-differences analysis to compare episode outcomes for patients admitted to BPCI vs non-BPCI hospitals. Outcomes were stratified for patients who were and were not attributed to an ACO. Participants included Medicare fee-for-service beneficiaries receiving care for medical and surgical episodes at US hospitals. Data were analyzed between October 1, 2018, and June 10, 2021.

EXPOSURES

Hospitalization for any of the 48 episodes (24 medical, 24 surgical) included in the BPCI at US hospitals participating in the BPCI for those episodes.

MAIN OUTCOMES AND MEASURES

The primary outcome was change in 90-day postdischarge institutional spending, and secondary outcomes included changes in quality and utilization.

RESULTS

A total of 7 108 146 beneficiaries (mean [SD] age, 76.9 [12.2] years; 4 101 081 women [58%]) received care for medical episodes, and 3 675 962 beneficiaries (mean [SD] age, 74.8 [10.1] years; 2 074 921 women [56%]) received care for surgical episodes. Compared with patients who were not attributed to ACOs, the association between bundled payments and changes in postdischarge institutional spending was larger among patients attributed to ACOs (-$323 difference; 95% CI, -$607 to -$39;  = .03) for medical episodes, but not surgical episodes. Attribution to an ACO also increased the strength of the association between bundled payments and changes in 90-day readmissions for both medical episodes (-0.98 percentage point difference; 95% CI, -1.55 to -0.41;  = .001) and surgical episodes (-0.84 percentage point difference; 95% CI, -1.32 to -0.35;  = .001).

CONCLUSIONS AND RELEVANCE

In this cohort study, compared with inclusion in bundled payments alone, simultaneous inclusion in both ACOs and bundled payment programs was associated with lower institutional postacute care spending and readmissions for medical episodes and lower readmissions but not spending for surgical episodes. Receiving care under models such as ACOs may improve episode outcomes under bundled payments.