Weight gain in patients with schizophrenia treated with risperidone, olanzapine, quetiapine or haloperidol: results of the EIRE study.

OBJECTIVES: The aim of this cross-sectional study, the EIRE study, was to assess the frequency of several side effects with antipsychotics in the clinical setting. This paper addresses the adverse effect of weight gain.

METHOD: Outpatients diagnosed of schizophrenia according to DSM-IV criteria and receiving a single antipsychotic (risperidone, olanzapine, quetiapine or haloperidol) for at least 4 weeks were consecutively recruited. Data were collected in a single visit, including data on demographic, clinical and treatment characteristics. Mean weight change was evaluated retrospectively by means of clinical charts and the weight at the time of the visit; in addition, the corresponding item of a modified version of the UKU, a Scandinavian side-effect rating scale, was used. Chi-squared test and logistic regression methods were used to analyze frequency of weight gain between treatments.

RESULTS: Out of 669 recruited, 636 evaluable patients were assessed. The treatment with the highest number of patients with weight gain as an adverse reaction on the UKU scale was olanzapine (74.5%), followed by risperidone (53.4%) and haloperidol (40.0%). The proportion of patients with clinically relevant weight gain (>or=7% increase versus initial weight) was also higher with olanzapine (45.7%) than with risperidone (30.6%) and haloperidol (22.4%). Five patients (13.5%) treated with quetiapine had some degree of weight gain according to the UKU scale, although no patient showed a clinically relevant weight gain (>or=7%). Treatment with olanzapine and risperidone were identified as risk factors of weight gain versus haloperidol. The risk of weight gain was higher in women (OR: 4.4), overweight patients (OR: 3.0) and in patients with <or=1 year of treatment (OR: 6.3) in the olanzapine group. A higher risk of weight gain in women (OR: 2.6) was also seen with risperidone.

CONCLUSION: Clinically relevant weight gain is clearly associated with olanzapine, and to lesser extent, with haloperidol and risperidone. Data for quetiapine were not conclusive because of the short duration of treatment.