Impact of Accountable Care Organizations on Utilization, Care, and Outcomes: A Systematic Review

Since 2010, more than 900 accountable care organizations (ACOs) have formed payment contracts with public and private insurers in the United States; however, there has not been a systematic evaluation of the evidence studying impacts of ACOs on care and outcomes across payer types. This review evaluates the quality of evidence regarding the association of public and private ACOs with health service use, processes, and outcomes of care. The 42 articles identified studied ACO contracts with Medicare ( N = 24 articles), Medicaid ( N = 5), commercial ( N = 11), and all payers ( N = 2). The most consistent associations between ACO implementation and outcomes across payer types were reduced inpatient use, reduced emergency department visits, and improved measures of preventive care and chronic disease management. The seven studies evaluating patient experience or clinical outcomes of care showed no evidence that ACOs worsen outcomes of care; however, the impact on patient care and outcomes should continue to be monitored.