Since the prevalence of obesity continues to increase, there is a demand for effective and safe anti-obesity agents that can produce and maintain weight loss and improve comorbidity. We did a meta-analysis of all published randomised controlled trials to assess the efficacy and safety of the newly approved anti-obesity agent rimonabant.

We searched The Cochrane database and Controlled Trials Register, Medline via Pubmed, Embase via WebSpirs, Web of Science, Scopus, and reference lists up to July, 2007. We collected data from four double-blind, randomised controlled trials (including 4105 participants) that compared 20 mg per day rimonabant with placebo.

Patients given rimonabant had a 4·7 kg (95% CI 4·1–5·3 kg; p<0·0001) greater weight reduction after 1 year than did those given placebo. Rimonabant caused significantly more adverse events than did placebo (OR=1·4; p=0·0007; number needed to harm=25 individuals [95% CI 17–58]), and 1·4 times more serious adverse events (OR=1·4; p=0·03; number needed to harm=59 [27–830]). Patients given rimonabant were 2·5 times more likely to discontinue the treatment because of depressive mood disorders than were those given placebo (OR=2·5; p=0·01; number needed to harm=49 [19–316]). Furthermore, anxiety caused more patients to discontinue treatment in rimonabant groups than in placebo groups (OR=3·0; p=0·03; number needed to harm=166 [47–3716]).

Our findings suggest that 20 mg per day rimonabant increases the risk of psychiatric adverse events—ie, depressed mood disorders and anxiety—despite depressed mood being an exclusion criterion in these trials. Taken together with the recent US Food and Drug Administration finding of increased risk of suicide during treatment with rimonabant, we recommend increased alertness by physicians to these potentially severe psychiatric adverse reactions.