Weight gain over 4 months in schizophrenia patients: a comparison of olanzapine and risperidone.

Weight gain frequently accompanies treatment with antipsychotics. In order to determine whether newer antipsychotic agents differ from each other with respect to weight gain, we compared two cohorts of patients with DSM-IV schizophrenia who had newly started treatment with either risperidone or olanzapine. After obtaining informed consent, data regarding body weight and height were culled from existing medical records of 100 patients (50 patients in each treatment group). Baseline body weight, close to the time of starting the new medication, and body mass index [BMI = weight (kg)/height (m) squared] were compared to the body weight and BMI following 4 months of treatment. There was no significant change in mean body weight or BMI in the group treated with risperidone (baseline weight = 83.1 kg +/- 20.5, follow-up = 82.8 kg +/- 19.9; matched pair t = 0.66, P = n.s.; baseline BMI = 29.6 +/- 9.4, follow-up = 29.5 +/- 9.1; matched pair t = 0.79, P = n.s.). However, in the group treated with olanzapine, there was a significant increase in both mean body weight and BMI (baseline weight = 84.9 kg +/- 25.0, follow-up = 87.1 kg +/- 25.1; matched pair t = 4.62, P < 0.001; baseline BMI = 29.5 +/- 7.4, follow-up = 30.3 +/- 7.5; matched pair t = 4.43, P < 0.001). In this naturalistic study, treatment with olanzapine was associated with a mean weight gain of about 2 kg from baseline, in patients with schizophrenia, while treatment with risperidone was associated with no mean weight change.