Weight gain induced by haloperidol, risperidone and olanzapine after 1 year: Findings of a randomized clinical trial in a drug-naive population

Background: There is little information about weight gain induced by antipsychotics at long-term. Objective: To quantify the weight gain induced by first (haloperidol) and second generation antipsychotics (olanzapine and risperidone) in a cohort of drug-naive subjects after 1 year of treatment. Methods: This is a prospective, randomized clinical trial, including a representative sample of first episode psychotic incident cases from a population area of 555.000 people. The main outcome measures were changes in body weight and body mass index at 3 months and at 12 months. Both a per protocol analysis and an intention to treat analysis were conducted. Results: A total of 164 drug-naive patients were included. At 12 months 144 patients were evaluated. Of them, 66% completed the protocol and 34% needed treatment switch. We found statistically significant differences in weight gain at 3 months: 3.8 kg (+/-4.1) for haloperidol, 5.9 kg (+/-5.1) for risperidone and 8.4 kg (+/-5.0) for olanzapine (F = 7.045; p=0.002). After 1 year the difference in weight gain had disappeared: 9.7 kg (+/-5.7) for haloperidol, 8.9 kg (+/-8.8) for risperidone and 10.9 kg (+/-7.2) for olanzapine (F = 0.817; p = 0.445). Conclusions: Drug-naive patients experience an extraordinary weight gain after I year of treatment with haloperidol, olanzapine or risperidone. The main difference among these treatments is the pattern of weight gain but not the final amount of weight gain. (C) 2007 Elsevier B.V. All rights reserved.