Real-world Use of the Aripiprazole Two-injection Start Regimen in Schizophrenia and Bipolar Disorder: A Cluster Analysis

Objective: Two-injection start regimen of aripiprazole once-monthly (AOM-TIS) is a practical strategy aimed at achieving rapid stabilization in psychiatric admissions.To address the limited real-world data from centers with high treatment resistance and polypharmacy, this study evaluated the effects of AOM-TIS on clinical profiles, medication use, and treatment processes.Methods: In this retrospective observational study of 111 patients, Cluster Analysis was utilized to identify distinct patient subgroups based on variables including diagnosis, length of stay, and antipsychotic load.Results: Most patients were female (72.1%) and diagnosed with bipolar disorder.A substantial proportion continued antipsychotic polypharmacy at discharge, with limited transition to monotherapy.Cluster analysis identified two distinct profiles: a High Antipsychotic Load-Resistant group (HAL-R; n = 56) with greater medication burden and longer hospitalization, and a Low Antipsychotic Load-Simplified group (LAL-S; n = 55) with shorter stays.Delayed AOM-TIS initiation correlated with longer hospitalization (r = 0.320, p = 0.001).However, the absolute timing of initiation did not differ significantly between the HAL-R and LAL-S subgroups.Conclusion: The real-world application of AOM-TIS appears to reflect differing patterns of use across clinical contexts, including its incorporation within complex polypharmacy in more resistant cases (HAL-R) and its use during transition toward maintenance-oriented treatment in less complex profiles (LAL-S).Earlier initiation is associated with shorter hospitalization; however, this relationship is likely influenced by confounding by indication, reflecting clinician-driven decisions based on baseline illness severity.