Impact of treatment with long‑acting injectable antipsychotics on hospitalization and relapse rates in schizophrenia spectrum disorders: a 3‑year follow-up mirror‑image study

Background: Long-acting injectable (LAI) antipsychotics are an important treatment option for the long-term treatment management of schizophrenia spectrum disorders (SSDs). Emerging evidences suggest a beneficial impact on long-term treatment outcomes, such as hospitalization and/or relapse risk. Objectives: We aimed to apply a 3-year follow-up mirror observation design to compare relapse as well as hospitalization rates and the number of hospitalization days during the 3 years before and after the start of LAI treatment in a sample of individuals with SSDs in a naturalistic outpatient clinical setting. Methods: We used a 3-year follow-up mirror-image design to compare hospitalization rates and duration, and the total number of clinical relapses in the 3 years before and after initiating LAI treatment in outpatients suffering from SSDs, switching from their oral counterparts. Results: Among 83 individuals screened, 56 adults (females, n = 20, 35.7%) with SSDs who began treatment with either first-generation (FGA) or second-generation (SGA) LAIs were included. Overall, switching from oral to LAI antipsychotic formulations significantly reduced both the number and duration of hospitalizations (from 10.15 to 0.18 average days) in treatment-compliant patients, as well as the overall number of relapses at 3 years of follow-up (from an average of 1.85 to 1.10). In the subgroup analysis, we found a reduced number of hospitalizations during the 3 years follow-up for both patients switched to SGA LAIs and FGA LAIs, but only if receiving LAI treatment for >6 consecutive months. This benefit was only reported in patients switched to LAI for the first time. Conclusion: This study highlights the effectiveness of LAIs as a maintenance treatment for SSDs, particularly for patients with longer LAI treatment duration. Future research may further identify the clinical characteristics of individuals with SSDs who may benefit most from LAI treatment.