BACKGROUND: The Medicare Shared Savings Program Accountable Care Organization is one of the largest Medicare Accountable Care Organization programs designed to promote value-based care. We sought to investigate whether participation in the Medicare Shared Savings Program Accountable Care Organization program was associated with lower surgical and postoperative care spending related to gastrointestinal cancer surgery. METHODS: Individuals who underwent gastrointestinal cancer surgery between 2016 and 2020 were identified from the Medicare database. Difference-in-differences analysis was used to evaluate risk-adjusted 30-day and 1-year hospital level cost savings before and after Accountable Care Organization participation. RESULTS: A total of 23,357 Medicare beneficiaries underwent gastrointestinal cancer surgery (pancreas: n = 2,747
11.8%
liver: n = 877, 3.8%
biliary tract: n = 1,168, 5%
colon: n = 15,845, 67.8%
rectum: n = 2,720, 11.6%) at 57 Accountable Care Organization-participating hospitals and 171 nonparticipating hospitals. Median patient age was 75 years (interquartile range, 71-81) with roughly one-half of patients being female (n = 12,207, 52.3%). Of note, participation in the Accountable Care Organization was not associated with reductions in total Medicare payments for 30-day surgical episodes (difference-in-differences, -23, 95% confidence interval, -,280 to -,035
P = .83) or for 1-year episodes (difference-in-differences, -,749, 95% confidence interval, -,261 to -62
P = .17). These trends were similar for other health care services including inpatient care, outpatient care, home health assistance, and skilled nursing facilities. CONCLUSION: Hospital Accountable Care Organization participation did not reduce health care expenditures or improve postoperative outcomes. The health care system needs new and innovative strategies to provide value-based care.