Predictors of antipsychotic-induced weight gain in first-episode psychosis: conclusions from a randomized, double-blind, controlled prospective study of olanzapine, risperidone, and haloperidol.

Background: Antipsychotic-induced weight gain is one of the most distressing adverse effects being observed in recent times. Most studies have been limited by several confounders.

Aim: To evaluate the predictors of antipsychotic-induced weight gain in drug-naive patients with first-episode psychosis treated with olanzapine, risperidone, or haloperidol and compare them with a healthy matched control group.

Methods: Newly diagnosed patients with first-episode schizophrenia treated with antipsychotic medication-olanzapine, risperidone, or haloperidol-and matched healthy controls were followed for 6 weeks. Body mass index (BMI), waist circumference, and weight changes and proportions of subjects with more than 7% weight gain were calculated. The predictors of weight gain were explored.

Results: Ninety-nine patients with first-episode schizophrenia and 51 healthy controls were examined. Waist circumference (r = -0.25; P < 0.01) and weight (r = -0.24; P < 0.01) at baseline in addition to the disease process (P < 0.001) as well as antipsychotic use (P < 0.001) were associated with greater increases in weight and BMI. Olanzapine (77%) had greater clinically significant weight gain as compared with risperidone (63%) and haloperidol (22%). Lower BMI at baseline and a diagnosis of undifferentiated schizophrenia were associated with antipsychotic-induced weight gain.

Conclusions: The results confirm clinically significant and substantial weight gain induced by antipsychotic treatment in drug-naive patients with first-episode schizophrenia and identify several risk factors for weight gain such as lower BMI scores, use of olanzapine, and a diagnosis of undifferentiated schizophrenia.