Preventive effect of aripiprazole once monthly on rehospitalization for bipolar disorder: A multicenter 1‐year retrospective mirror image study

AIM: We conducted a 1‐year retrospective mirror‐image study to investigate the effect of aripiprazole once monthly (AOM) on rehospitalization for bipolar disorder. METHODS: Participants were recruited from psychiatric emergency and acute care hospitals in western Japan. We included 39 participants with bipolar disorder who had been administered AOM for at least 1 year with no missing medical records during the observational period. The primary outcomes were rehospitalization rate, number of rehospitalizations, total hospitalization days, and time to rehospitalization in the context of overall psychiatric readmissions. The significance level was set at p < 0.05. RESULTS: AOM significantly reduced the rehospitalization rate from 23/39 (59%) to 7/39 (18%) (p = 0.001). The number of rehospitalizations decreased significantly from a mean of 0.85 per person‐year to 0.41 per person‐year (p = 0.048). The total hospitalization days significantly decreased from a mean of 34.9 days to 14.4 days (p = 0.008). AOM significantly prolonged the time to rehospitalization (p < 0.001). CONCLUSION: This study found that AOM reduces overall psychiatric rehospitalization for bipolar disorder based on data from 1 year before and after AOM administration in the real‐world setting. Future studies should examine the robustness and persistence of the rehospitalization preventive effect of AOM with larger sample sizes and longer observation periods beyond 1 year.