Effect of long-acting injectable antipsychotics on 1-year hospitalization in bipolar disorder: a mirror-image study

Long-acting injectable (LAI) antipsychotics are often used for the long-term management also of bipolar disorder (BD). Nonetheless, evidence on their effect on pragmatic outcomes such as hospitalization risk in BD is inconsistent. We carried out a mirror-image study comparing rates and number of days of hospitalization, one year before and after the initiation of LAI treatment, in a sample of subjects with BD. Participants were selected from the STAR Network Depot Study, a pragmatic, observational, multicenter research involving a cohort of inpatients and outpatients consecutively started on LAI treatment. Variations in rates and in total number of days of hospitalization between the 12 months before and those after treatment initiation were analyzed. Among 461 individuals screened for eligibility, we included 71 adults with BD, initiated either on first- (FGA) or second-generation (SGA) LAIs. We found a significant decrease in terms of 12-month hospitalization rates (p < 0.001) and number of days (p < 0.001) after LAI initiation, without any effect by age, gender, alcohol/substance use disorders, and symptom severity. Subgroup analyses based on antipsychotic class, history of LAI treatment, and concomitant oral medications, confirmed the decreasing trend on both hospitalization rates and number of days. However, these reductions were not significant among participants who continued this treatment for less than 6 months. Comprehensively, this study supports the role of LAIs as effective maintenance treatment options for BD. Further research is needed to identify clinical characteristics of people with BD who would most benefit from long-acting formulations of antipsychotics.