Trajectories of body mass index change in first episode of mania: 3-year data from the Systematic Treatment Optimization Program for Early Mania (STOP-EM)

Background Overweight/obesity is common in patients with bipolar disorder (BD). However, little is known about longitudinal trends in body mass index (BMI) in patients with BD. Furthermore, most studies on the association between BMI and clinical outcomes are restricted by retrospective and cross-sectional designs. This study uses prospectively-gathered data from a first episode mania (FEM) cohort to examine the trajectories of BMI change and analyze their association with clinical outcomes during a 3-year period. Methods A total of 110 FEM patients receiving maintenance treatment and 57 healthy subjects were included. The comparisons of BMI trajectories were examined using linear mixed-effects models. The effects of BMI on time to any mood episode were assessed by Cox proportional-hazards models. Results The estimated mean BMI in FEM patients significantly increased from 24.0 kg/m² to 25.4 kg/m² within 6 months. FEM patients had a significant BMI increase trend over the entire 3 years follow-up, which was not observed in the control group. No significant difference in BMI trajectory between patient subgroups (baseline normal-weight vs. overweight/obese; male vs. female) was observed. BMI increase predicted an increased risk of recurrence during follow-up visits (HR=1.50, 95% CI: 1.06–2.13; p=0.02). Limitations Naturalistic design does not allow the accurate assessments of the impact of pharmacologic treatments on BMI. Conclusions FEM patients showed a significantly increased BMI trajectory compared to healthy subjects. Furthermore, BMI increase is independently associated with an increased risk of recurrence to a new mood episode during 3-year follow-up. Thus, weight control prevention is needed in the early course of BD.