Changes in spending and quality after ACO contract participation for dually eligible beneficiaries with mental illness.

BACKGROUND: Fragmented care and misaligned payment across Medicare and Medicaid lower care quality for dually eligible beneficiaries with mental illness. Accountable care organizations aim to improve the quality and value of care.

METHODS: Using Medicare fee-for-service Part A and B claims data from 2009 to 2017 and a difference-in-differences design, we compared the spending and utilization of dually eligible beneficiaries with mental illness that were and were not attributed to Medicare ACO providers before and after ACO contract entry.

RESULTS: Dually eligible beneficiaries with mental illness (N = 5,157,533, 70% depression, 22% bipolar, 27% schizophrenia and other psychotic disorders) had average annual Medicare spending of $17,899. ACO contract participation was generally not associated with spending or utilization changes. However, ACO contract participation was associated with higher rates of follow-up visits after mental health hospitalization: 1.17 and 1.30 percentage points within 7 and 30 days of discharge, respectively (p < 0.001). ACO-attributed beneficiaries with schizophrenia, bipolar, or other psychotic disorders received more ambulatory visits (393.9 per 1000 person-years, p = 0.002), while ACO-attributed beneficiaries with depression experienced fewer emergency department visits (-29.5 per 1000 person-years, p = 0.003) after ACO participation.

CONCLUSIONS: Dually eligible beneficiaries served by Medicare ACOs did not have lower spending, hospitalizations, or readmissions compared with other beneficiaries. However, ACO participation was associated with timely follow-up after mental health hospitalization, as well as more ambulatory care and fewer ED visits for certain diagnostic groups.

IMPLICATIONS: ACOs that include dually eligible beneficiaries with mental illness should tailor their designs to address the distinct needs of this population.