Low Adherence Rates to Atypical Antipsychotic Therapy in Patients with Schizophrenia

Minneapolis—A retrospective database study of insurance claims for 63,000 adults with schizophrenia who were prescribed certain oral atypical antipsychotic (AA) medications found that less than one-third (approximately 29.4%) remained adherent to therapy for the 12 months after the initial claim. Data showed new initiators of an AA (n=14,677) were more likely to discontinue the drug than existing users (n=48,322) (patients whose claims history reflected AA use during the 12-month baseline period). At a poster presentation at the AMCP meeting, researchers presented results of a study designed to assess rates of persistence, augmentation, switching, and noncompliance among patients with schizophrenia. The poster was titled Utilization of Atypical Antipsychotic Treatment Among Adults with Schizophrenia. The findings demonstrate a need for better management of individuals with schizophrenia, the researchers said. Using Thomson Reuters MarketScan Research Databases, researchers reviewed inpatient and outpatient pharmacy claims between 2002 and 2008 for adults with a diagnosis of schizophrenia who filled ≥1 prescription for aripiprazole, olanzapine, paliperidone, quetiapine, risperidone, or ziprasidone. The claim date for the initial AA prescription was the index prescription date (IPD) and served as a reference point for determining study eligibility. For the analyses, investigators only included data pertaining to patients continuously enrolled in Medicare, Medicaid, or a commercial health insurance plan for a 24-month period encompassing 12 months before the IPD and 12 months after. Data were excluded for patients with diagnosis codes of schizoaffective or bipolar disorder. Sex (40.8% female) and age (mean, 47.1 years) were well balanced between the cohorts. At baseline, similar proportions of patients in the new and existing user groups had comorbid conditions such as anxiety, depression, substance abuse, diabetes, obesity, hypertension, and hypercholesterolemia. For patients with an initial claim for 1 AA, olanzapine was the drug most often prescribed in both cohorts (29.6%), followed by risperidone (27.3%) and quetiapine (9.7%). New initiators were more likely than existing users to require concomitant typical antipsychotics at baseline (36.8% vs 28.4%, respectively), but they were less likely to take antidepressants, benzodiazepines, and mood stabilizers. Among existing users, 33.9% were adherent, defined as having a medication possession ratio ≥80%; adherence fell to 14.8% among new initiators. Individuals whose claims showed gaps in index AA coverage lasting >15 days but <30 days, but no evidence that they switched to another AA or had their regimen augmented, were considered noncompliant. Noncompliance was first observed in the new initiator cohort at a mean of 96 days compared with 117 days for existing users. More than half (54.6%) of patients in the new initiator cohort discontinued their index AA by a mean of 65 days after the IPD. The discontinuation rate in the existing user group was lower (21.9%), with discontinuation occurring at a mean of 97 days after the IPD. In both groups, the majority of patients discontinued therapy. More than three-quarters (77.6%) of new initiators discontinued AAs, and a similar proportion (77.4%) discontinued all antipsychotic therapy. Rates of AA discontinuation and discontinuation of all antipsychotics declined to 51.7% for each end point in the existing user cohort. Although 41.2% of existing users demonstrated persistent therapy use during the 12-month follow-up period, with ≤15 days elapsing between refills of the index AA and an absence ≥30 days of continuous concomitant use of a nonindex AA, persistence dropped to 17.6% among new initiators. The authors said usage patterns were fairly consistent, regardless of the index AA or insurance plan. AAs are typical first-line treatments for schizophrenia, the authors said, with several available. Despite this, rates of persistent use are low and discontinuation is frequent. Preventing poor treatment outcomes due to low adherence rates for patients with schizophrenia is likely to require greater effort to manage therapy, they added. This study was funded by Merck & Co, Inc.