Efficacy of diazepam as an anti-anxiety agent: meta-analysis of double-blind, randomized controlled trials carried out in Japan.

Diazepam is one of the most widely used, broad-spectrum anti-anxiety agents. The aim of this study was to evaluate the efficacy of diazepam, and to establish whether it is more effective than a placebo in improving the various neurotic anxiety states seen in patients with neurosis or psychosomatic disease. Of the recently established comprehensive register of psychotropic drug trials carried out in Japan, a total of 17 double-blind, randomized controlled trials were identified on the treatment of neurosis using anti-anxiety compounds, in which both diazepam and placebos were used. Meta-analysis of these 17 studies demonstrated that diazepam is significantly more effective than a placebo (relative risk 1.35, 95% confidence interval 1.21-1.51, number needed to treat 9). The maximal effective dose of diazepam seems to be 12 or 18 mg/day with a treatment duration of 2 or more weeks. There was no significant difference between the effects of placebo and a diazepam dose of 6 mg/day. Caution should be exercised in assessing these results, however, since this is the first meta-analysis showing the significant effectiveness of diazepam in the treatment of neurosis or psychosomatic disease. Copyright 2003 John Wiley & Sons, Ltd.