A retrospective analysis of the short-term effects of olanzapine and quetiapine on weight and body mass index in children and adolescents.

STUDY
OBJECTIVE: To evaluate changes in short-term weight and body mass index (BMI) in children and adolescents receiving olanzapine or quetiapine.
DESIGN: Retrospective study Setting. Austin State Hospital, Austin, Texas. PATIENTS: One hundred three patients younger than 18 years who were admitted to the hospital and treated with olanzapine (50 patients) or quetiapine (53) for at least 2 weeks between October 1, 1997, and October 31, 2001. INTERVENTION: Treatment with at least 2 weeks of olanzapine or quetiapine.
MEASUREMENTS AND MAIN RESULTS: Mean+/-SD daily doses of olandzapine and quetiapine were 13.9+/-7.3 and 510.9+/-250.3 mg, respectively Weight and height were measured at baseline and 14 or more days after baseline. Body mass index (in kg/m2) was calculated using serial measurements of weight and height, and change in BMI was determined. The olanzapine group gained an average of 3.8 kg, the quetiapine group 0.03 kg. In the olanzapine group, BMI increased by an average of 1.3 kg/m2; in the quetiapine group, BMI decreased by 0.2 kg/m2. After controlling for baseline differences, significant between-group differences in weight and BMI change were noted. Change in BMI correlated significantly with baseline BMI in quetiapine-treated girls.
CONCLUSION: Patients taking olanzapine had greater increases in weight and BMI than those taking quetiapine. Further studies are necessary to determine the relative risk, magnitude, and time course of antipsychotic-induced weight gain in this patient population.