A Comparison of Weight Change During Treatment With Olanzapine or Aripiprazole: Results From a Randomized, Double-Blind Study

Background: Weight gain is a side effect of therapy with many atypical antipsychotics and may have important clinical repercussions with respect to long-term health and treatment compliance. The primary objective of this double-blind study was to compare the safety and tolerability of aripiprazole and olanzapine in patients with schizophrenia as evidenced by the percentage of patients exhibiting significant weight gain. Method: This was a 26-week, multicenter, randomized, double-blind, active-controlled trial in patients with DSM-IV schizophrenia who were in acute relapse and required hospitalization. Significant weight gain was defined as a ≥ 7% increase in body weight from baseline. Body weight, Positive and Negative Syndrome Scale, and Clinical Global Impressions-Improvement scale (CGI-I) assessments were performed at baseline and at regular intervals during the study. The study period was from April 2000 through June 2001. Results: 317 patients were randomly assigned to aripiprazole (N = 156) or olanzapine (N = 161). Compared with those treated with aripiprazole, a greater proportion of patients treated with olanzapine exhibited clinically significant weight gain during the trial. By week 26, 37% of olanzapine-treated patients had experienced significant weight gain compared with 14% of aripiprazole-treated patients (p<.001). Statistically significant differences in mean weight change were observed between treatments beginning at week 1 and sustained throughout the study. At week 26, there was a mean weight loss of 1.37 kg (3.04 lb) with aripiprazole compared with a mean increase of 4.23 kg (9.40 lb) with olanzapine among patients who remained on therapy (p <.001). Changes in fasting plasma levels of total cholesterol, high-density lipoprotein cholesterol, and triglycerides were significantly different in the 2 treatment groups, with worsening of the lipid profile among patients treated with olanzapine. There was a consistent and sustained improvement in symptoms in patients who remained on therapy with either olanzapine or aripiprazole as assessed by CGI-I scores and responder rates throughout the study. Conclusion: Olanzapine had a greater impact on patients' weight than aripiprazole. Significant differences in favor of aripiprazole were also observed in the effects of therapy on plasma lipid profile. Both treatment groups achieved comparable clinically meaningful improvements on efficacy measures. The observed effects on weight and lipids indicate a potentially lower metabolic and cardiovascular risk in patients treated with aripiprazole compared with those treated with olanzapine.