Atypical antipsychotics and weight gain in Chinese patients: a comparison of olanzapine and risperidone

To compare the effect of olanzapine with that of risperidone on weight change among Chinese patients in Hong Kong.

The body weight of subjects maintained on olanzapine or risperidone treatment was recorded at the outpatient clinic of a teaching hospital. Pretreatment weight of the subjects was retrieved from case records. Subjects on olanzapine treatment were matched in sex, age, and diagnosis with those on risperidone treatment, and demographic and clinical data were analyzed. The study was conducted in May and June 2002.

Twenty-eight olanzapine-risperidone matched pairs were studied. All were diagnosed with DSM-IV schizophrenia. In patients treated with olanzapine and risperidone, respectively, mean +/- SD duration of treatment with atypical neuroleptics was 103.5 +/- 47.4 weeks and 93.2 +/- 50.6 weeks (range, 21-255 weeks), and mean doses were 12.4 +/- 6.7 mg/day and 4.5 +/- 2.8 mg/day. The mean +/- SD weight gain of subjects on treatment with olanzapine and risperidone, respectively, was 8.34 +/- 5.97 kg (18.53 +/- 13.27 lb) and 2.74 +/- 8.09 kg (6.09 +/- 17.98 lb) with a statistically significant difference at p < .005. Lower baseline body weight and body mass index were associated with greater weight gain in both olanzapine- and risperidone-treated subjects. Gender, age, mean daily dose, and duration of treatment had no effect on weight change.

Treatment with olanzapine was associated with significantly greater weight gain than treatment with risperidone in Chinese schizophrenia patients in Hong Kong. The effect of adjunctive anticonvulsant treatment on weight gain requires further study.