Medication Adherence and Hospitalization Among Patients With Schizophrenia Treated With Antipsychotics

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This analysis assessed rates of medication adherence and predictors of nonadherence and hospitalization among patients treated with long-acting injectable and oral antipsychotic therapies. 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. Patients were considered adherent if they had an MPR ≥ .8. A total of 12,032 patients met selection criteria. The mean ± SD MPR was .79 ± .23, medication persistence was 94.1% ± 16.4%, medication consistency was 83.3% ± 16.4%, and the maximum gap in treatment was 29.7 ± 41.4 days. Thirty-seven percent of patients were hospitalized for any cause, and 32% had a psychiatric hospitalization. Predictors of nonadherence included newly starting treatment; younger age; a substance abuse diagnosis; use of a mood stabilizer, antidepressant, anxiolytic, or anticholinergic; 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. 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.