Relapse and Treatment Adherence in Patients with Schizophrenia Switching from Paliperidone Palmitate Once-Monthly to Three-Monthly Formulation: A Retrospective Health Claims Database Analysis

PURPOSE: Relapse and treatment adherence to paliperidone palmitate once-monthly (PP1M) and three-monthly (PP3M) formulations in patients with schizophrenia were evaluated and compared using health claims data. PATIENTS AND METHODS: Data (June 2015─June 2018) obtained from the MarketScan(®) Multi-State Medicaid Database were retrospectively analyzed. Patients aged ≥18 years with ≥1 claim for schizophrenia diagnosis prior to and/or at index date (i.e., date of first PP3M prescription record for PP3M patients and same month/year as the matched PP3M patients for PP1M patients) and continuous enrollment in the insurance plan for ≥12 months prior to index date (baseline) were included. PP1M cohort included patients who received ≥4 PP1M doses. PP3M patients were matched with PP1M patients (1:3) using propensity score matching and prevalent new user design. Outcome measures were relapse rate, time to relapse, proportion of days covered (PDC), and level of treatment adherence defined by PDC in five levels. Time to relapse was compared by Kaplan–Meier survival curves and log-rank test with the hazard ratio calculated using Cox proportion hazards model; PDC by t-test, and relapse rate and PDC categories by chi-square test. RESULTS: A total of 1564 patients (428 PP3M and 1136 PP1M) were included. Relapse rate was lower in PP3M cohort (10.5%) compared with PP1M cohort (15.7%). Incidence rate of relapse was 8.98/100 person-years (PY) in PP3M cohort and 13.81/100 PY in PP1M cohort. After a mean (SD) follow-up of 456.1 (240.28) days in PP3M cohort and 465.4 (237.95) days in PP1M cohort, PP3M patients had a significantly lower relapse risk (hazard ratio: 0.65, 95% CI: 0.47, 0.90) than PP1M patients. Treatment adherence was significantly (p<0.0001) higher in PP3M versus PP1M cohort. CONCLUSION: Risk of relapse was significantly lower, and treatment adherence was significantly higher in PP3M cohort compared with PP1M cohort. Higher treatment adherence was associated with lower relapse rate.