Abstract
BACKGROUND: The long-term impact of affordable care organizations (ACOs) on cancer spending remains unknown. The authors examined whether practices that became ACOs altered their spending for patients with cancer in the first 4 years after ACO implementation. METHODS: By using national Medicare data from 2011 to 2017, a random sample of 20% of fee-for-service Medicare beneficiaries aged 65 years and older with cancer was obtained (n = 866,532), and each patient was assigned to a practice. Practices that became ACOs in the Medicare Shared Savings Program were matched to non-ACO practices. Total, cancer-specific, and service category-specific yearly spending per patient was calculated. A difference-in-differences model was used to determine spending changes associated with ACO status for patients with cancer in the 4 years after ACO implementation. RESULTS: The introduction of ACOs did not have a significant impact on overall spending for patients with cancer in the 2 years after ACO implementation (difference, -$38; 95% CI, -$268, $191; P = .74). Changes in spending also did not differ between ACO and non-ACO patients within service categories or among the 11 cancer types examined. The lack of difference in spending for patients with cancer in ACO and non-ACO practices persisted in the third and fourth years after ACO implementation (difference, -$120; 95% CI, -$284, $525; P = .56). CONCLUSIONS: ACOs did not significantly change spending for patients with cancer in the first 4 years after their implementation compared with non-ACOs. This prompts a reevaluation of the current efficacy of ACOs in reducing spending for cancer care and may encourage policymakers to reconsider the incentive structures of ACOs. LAY SUMMARY: Accountable care organizations (ACOs) were developed to curtail health care spending and improve quality, but their effects on cancer spending in their first 2 years have been minimal. The long-term impact of ACOs on cancer spending remains unknown. By using data from 866,532 Medicare beneficiaries with cancer, the authors observed that the association of a practice with an ACO did not significantly change total yearly spending per patient in the first 4 years after ACO implementation. This finding prompts a reevaluation of the current efficacy of ACOs in reducing spending for cancer care.