Introduction: Few studies have compared adherence between long-acting injectable antipsychotics, especially for newer agents like aripiprazole once-monthly 400 mg (AOM 400; aripiprazole monohydrate) and oral antipsychotics, in patients with schizophrenia or bipolar I disorder (BD-I) in a real-world setting.
Methods: Two separate retrospective cohort analyses using Truven MarketScan data from January 1, 2012 to June 30, 2016 were conducted to compare medication adherence and discontinuation in patients with schizophrenia or BD-I who initiated treatment with AOM 400 vs. patients changed from one oral antipsychotic monotherapy to another. Adherence was defined as proportion of days covered (PDC) ≥ 0.80 in the year following the index date. Linear regression models examined the association between AOM 400 and oral antipsychotic cohorts and medication adherence. Kaplan-Meier curves and Cox regression estimated time to and risk of discontinuation, while adjusting for baseline covariates. A sensitivity analysis was conducted using a combination of propensity score matching and exact matching to create matched cohorts.
Results: Final cohort sizes were as follows-Schizophrenia: AOM 400 n = 408, oral antipsychotic n = 3361; BD-I: AOM 400 n = 413, oral antipsychotic n = 15,534. In patients with schizophrenia, adjusted mean PDC was higher in patients in the AOM 400 cohort vs. the oral antipsychotic cohort (0.57 vs. 0.48 P < 0.001), and patients in the oral antipsychotic cohort had a higher risk of discontinuing treatment vs. the AOM 400 cohort (HR 1.45, 95% CI 1.29-1.64). For patients with BD-I, adjusted mean PDC was higher for the AOM 400 cohort (0.59 vs. 0.44, P < 0.001), and patients in the oral antipsychotic cohort had a higher risk of discontinuation (HR 1.71, 95% CI 1.53-1.92).
Conclusions: In a real-word setting, AOM 400 resulted in a significantly higher percentage of patients with a PDC ≥ 0.80 and significantly longer time to treatment discontinuation compared to patients with schizophrenia or BD-I who received treatment with an oral antipsychotic.
Funding: Otsuka Pharmaceutical Development and Commercialization, Inc. and Lundbeck.
Keywords: Adherence; Bipolar I disorder; Long-acting antipsychotics; Neurology; Schizophrenia.