ACO Participation Associated With Decreased Spending For Medicare Beneficiaries With Serious Mental Illness.

Serious mental illness (SMI) is a major source of suffering among Medicare beneficiaries. To date, limited evidence exists evaluating whether Medicare accountable care organizations (ACOs) are associated with decreased spending among people with SMI. Using national Medicare data from the period 2009-17, we performed difference-in-differences analyses evaluating changes in spending and use associated with enrollment in the Medicare Shared Savings Program (MSSP) among beneficiaries with SMI. After five years, participation in MSSP ACOs was associated with small savings for beneficiaries with SMI (-$233 per person per year) in total health care spending, primarily related to savings from chronic medical conditions (excluding mental health; -$227 per person per year) and not from savings related to mental health services (-$6 per person per year). Savings were driven by reductions in acute and postacute care for medical conditions. Further work is needed to ensure that Medicare ACOs invest in strategies to reduce potentially unnecessary care related to mental health disorders and to improve health outcomes.