Predictors of Long-Acting Injectable Antipsychotic Medication Use in Patients with Schizophrenia Spectrum, Bipolar, and Other Psychotic Disorders in a US Community-based, Integrated Health System

Abstract

Background and Hypothesis. Long-acting injectable (LAI) antipsychotics improve patient outcomes and are recommended by treatment guidelines for patients with limited medication adherence in schizophrenia spectrum, bipolar, and other psychotic disorders. Reports of LAI antipsychotic use in these disorders and if use aligns with treatment guidelines are lacking. This study aimed to re- port patient characteristics associated with LAI antipsy- chotic use in these disorders. Study Design. Retrospective observational study of patients ≥18-years-old with bipolar or psychotic disorders at a large, integrated, community- based health system. Patient demographic and clinical characteristics served as exposures for the main outcome of adjusted odds ratio (aOR) for LAI versus oral antipsy- chotic medication use from January 1, 2017 to December 31, 2023. Study Results. There were N = 2685 LAI and N = 31 531 oral antipsychotic users. Being non-white (aOR = 1.3-2.0; P < .0001), non-female (aOR = 1.5; P < .0001), from a high deprivation neighborhood (NDI, aOR = 1.3; P < .0007), having a higher body mass index (BMI, aOR = 1.3-1.7; P < .0001), psychotic (aOR = 1.6, P < .0001), or substance use dis- order (aOR = 1.4; P < .0001), and outpatient psychiatry (aOR = 2.3-7.5; P < .0001) or inpatient hospitalization (aOR = 2.4; P < .0001) utilization in the prior year with higher odds and age ≥40 (aOR = 0.4-0.7; P < .0001) or bipolar disorder (aOR = 0.9; P < .05) were associated with lower odds of LAI use. Non-white, non-female, age 18-39, and high NDI patients had higher LAI use re- gardless of treatment adherence markers. Smoking and cardiometabolic markers were also associated with LAI use. Conclusions. Demographic and clinical factors are as- sociated with increased LAI use irrespective of treatment adherence. Research on utilization variation informing eq- uitable formulation use aligned with treatment guideline recommendations is warranted.