OBJECTIVE: This analysis assessed rates of medication adherence and predictors of nonadherence and hospitalization among patients treated with long-acting injectable and oral antipsychotic therapies. METHODS: Data were from a retrospective analysis of Florida Medicaid recipients with schizophrenic disorder (ICD-9-CM code 295.XX) who received a prescription for an antipsychotic between July 1, 2004, and June 30, 2005. Patients were required to have filled one additional antipsychotic prescription during follow-up. Adherence measures included medication possession ratio (MPR), medication persistence, medication consistency, and maximum gap in treatment. Multivariate logistic regression models identified predictors of nonadherence and hospitalization. RESULTS: Patients were considered adherent if they had an MPR +AD4-/+AD0- .8. A total of 12,032 patients met selection criteria. The mean SD MPR was .79 .23, medication persistence was 94.1+ACU- 16.4+ACU-, medication consistency was 83.3+ACU- 16.4+ACU-, and the maximum gap in treatment was 29.7 41.4 days. Thirty-seven percent of patients were hospitalized for any cause, and 32+ACU- had a psychiatric hospitalization. Predictors of nonadherence included newly starting treatment+ADs- younger age+ADs- a substance abuse diagnosis+ADs- use of a mood stabilizer, antidepressant, anxiolytic, or anticholinergic+ADs- and receipt of long-acting first-generation antipsychotics. Receipt of long-acting second-generation therapy or receipt of both first- and second-generation medications was associated with lower likelihood of nonadherence. Predictors of hospitalization risk included a diagnosis of other psychoses or substance abuse, anticholinergic use, and nonadherence to therapy. CONCLUSIONS: Results document rates of antipsychotic adherence and predictors of nonadherence and hospitalization. Findings may be useful to health plan administrators, formulary decision makers, and physicians
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