Predictors and Moderators of Antipsychotic-Related Weight Gain in the Treatment of Early-Onset Schizophrenia Spectrum Disorders Study

Background: Antipsychotic-related weight gain is a common clinically relevant side effect when treating psychotic disorders in pediatric populations, yet few predictors and no moderators of antipsychotic-related weight gain are known.

Methods: The Treatment of Early-Onset Schizophrenia Spectrum Disorders (TEOSS) study randomized 119 youths (age 8-19 years) with schizophrenia or schizoaffective disorder to 8 weeks of antipsychotic treatment with molindone, risperidone, or olanzapine and assessed treatment response and side effects. In this secondary analysis, we used multivariable linear regression and receiver operating characteristic analysis to investigate predictors and moderators of weight change and percent weight change from baseline to week 8.

Results: Treatment assignment was the most discriminant predictor of weight change [F(2, 66) = 17.00, p < 0.001] and percent weight change [F(2, 66) = 16.85, p < 0.001]. Mean weight gain was 0.74 (standard deviation ±3.51) kg for molindone, 4.13 ± 3.79 kg for risperidone, and 7.29 ± 3.44 kg for olanzapine. After adjusting for treatment assignment, lower pretreatment hemoglobin A1C (HgbA1C) predicted more weight gain [F(1, 55) = 4.71, p = 0.03]. Diagnosis (schizoaffective vs. schizophrenia) moderated weight change [F(2, 63) = 6.02, p = 0.004] and percent weight change [F(2, 63) = 5.26, p = 0.008] such that schizoaffective diagnosis predicted larger weight gain for youths in the risperidone treatment arm. Age, sex, family income, baseline weight, and symptoms neither predicted nor moderated weight change or percent weight change.

Conclusion: We identified prognostic subgroups and novel risk factors for antipsychotic-related weight gain. We confirmed that antipsychotic choice is extremely important for predicting future weight gain. We also found that younger age did not predict greater weight gain, in contrast to prior studies. Our findings require replication in an independent sample because we did not adjust for multiple comparisons to minimize false negatives. ClinicalTrials.gov Identifier: NCT00053703.