Assessing Outcomes Between Risperidone Microspheres and Paliperidone Palmitate Long-Acting Injectable Antipsychotics Among Veterans

Abstract

BACKGROUND Long-acting injectable antipsychotics (LAIAs) are integral for managing schizophrenia, schizoaffective disorder, and bipolar I disorder among veterans. Studies comparing LAIAs, such as risperidone microspheres and paliperidone palmitate, are limited. The primary objective of our study was to compare the number of psychiatric hospitalizations among veterans initiated on risperidone microspheres and those taking paliperidone palmitate pre- and post-LAIA initiation. METHODS We included veterans who had received ≥ 2 injections of risperidone microspheres or paliperidone palmitate between January 1, 2016 and December 31, 2018. Nonadherence was defined as missing an injection by > 3 days for risperidone microspheres and > 7 days for paliperidone palmitate. Pre-LAIA and post-LAIA hospitalizations and rehospitalizations were assessed using a pre-post design with equivalent periods. Descriptive statistics were used for demographics and diagnoses. Nonparametric tests were used to analyze primary and secondary outcomes. RESULTS The study included 97 veterans; 44 took risperidone microspheres and 53 received paliperidone palmitate. Participants' average mean (SD) age was 46 (13.8) years, 92% were male, and 94% were diagnosed with schizophrenia or schizoaffective disorder. Veterans administered risperidone microspheres had fewer mean (SD) post-LAIA hospitalizations (0.4 [1.0] vs 0.9 [1.5]; P = .02), were less likely to be rehospitalized (22.7% vs 47.2%; P = .013) and had a shorter mean (SD) treatment duration (41.6 [40.2] vs 58.2 [45.7] weeks; P = .04) compared with paliperidone palmitate. CONCLUSION Veterans receiving risperidone microspheres had fewer posttreatment psychiatric hospitalizations and were less likely to be rehospitalized.