Ten placebo-controlled RCTs (n=1,500) were included in the review.
There was no evidence of statistical heterogeneity between trials.
Augmentation of standard antidepressants was associated with a statistically significant increase in remission (RR 1.75, 95% CI: 1.36, 1.63, p<0.0001) and response rates (RR 1.35, 95% CI: 1.13, 1.63, p<0.001).
Treatment with placebo, compared with intervention, was associated with a statistically significant lower rate of discontinuation due to adverse events (RR 3.38, 95% CI: 1.98, 5.76, p<0.0001). There was no difference between groups in terms of the overall discontinuation rate (RR 1.18, 95% CI: 0.93, 1.49, p=0.929) and rate of discontinuation due to inefficacy (RR 0.66, 95% CI: 0.39, 1.13, p=0.133).