Weight Gain and Metabolic Changes in Patients With First-Episode Psychosis or Early-Phase Schizophrenia Treated With Olanzapine: A Meta-Analysis

BACKGROUND: Patients with first-episode psychosis or early-phase schizophrenia are susceptible to olanzapine-associated weight gain and cardiometabolic dysregulation. This meta-analysis characterized weight and metabolic effects observed during olanzapine treatment in randomized clinical trials in this vulnerable patient population. METHODS: PubMed, EMBASE, and Dialog were searched for randomized controlled trials (RCTs) reporting weight or cardiometabolic outcomes associated with olanzapine treatment in first-episode psychosis or early-phase schizophrenia. Random-effects meta-analysis and meta-regression were conducted using R v4.0.5. RESULTS: Of 1203 records identified, 26 RCTs informed the analyses. The meta-analytic mean (95% CI) weight gain was 7.53 (6.42–8.63) kg in studies (n = 19) that reported weight gain with olanzapine treatment. Stratified by duration, the mean (95% CI) weight gain was significantly higher in studies >13 weeks in duration than in those lasting ≤13 weeks: 11.35 (10.05–12.65) vs 5.51 (4.73–6.28) kg, respectively. Despite between-study variability, increases from baseline in most glycemic and lipid parameters were generally small in studies of both ≤13 and >13 weeks. There were no correlations, however, between weight gain and metabolic parameter changes when stratified by study duration. CONCLUSIONS: In RCTs enrolling patients with first-episode psychosis or early-phase schizophrenia, olanzapine was consistently associated with weight gain that was greater in studies lasting >13 weeks compared with those of ≤13 weeks. Metabolic changes observed across studies suggest that RCTs may underestimate metabolic sequelae vs real-world treatment observations. Patients with first-episode psychosis or early-phase schizophrenia are vulnerable to olanzapine-associated weight gain; strategies minimizing olanzapine-associated weight gain should be carefully considered.