Adherence to Antipsychotic Therapy: Association With Hospitalization and Medicare Spending Among Part D Enrollees With Schizophrenia

OBJECTIVE: This study examined relationships among antipsychotic adherence, hospitalization, and hospital expenditures in a sample of 13,861 Medicare Part D enrollees with schizophrenia. METHODS: Utilization and expenditure data were obtained from the Centers for Medicare and Medicaid Services Chronic Conditions Warehouse for 2011 and 2012. Adherence was measured with the proportion of days covered and stratified into four categories. Probit regressions and two-part generalized linear models were used to examine relationships between adherence in year 1 and outcomes in year 2. RESULTS: Adherence to antipsychotic therapy was associated with a significantly lower probability of psychiatric hospitalization and significantly lower psychiatric hospital expenditures, with the largest effect sizes observed for the most highly adherent beneficiaries. There was no relationship between antipsychotic adherence and hospitalizations or expenditures for nonpsychiatric conditions. CONCLUSIONS: Adherence to antipsychotics among Medicare Part D enrollees with schizophrenia was associated with significantly lower probability of psychiatric hospitalization and lower hospital expenditures.