Seventeen RCTs were included (n=3,523). The number of participants ranged from 68 to 382 in the included studies. Seven studies were classified as having an adequate ITT analysis, four reported an adequate method of randomisation and one reported an adequate method of allocation concealment.
There was no statistically significant difference between venlafaxine and SSRI in remission rate (RR 1.05, 95% CI: 0.97, 1.13) based on 15 trials. Statistical heterogeneity was low, although the authors noted that there was considerable variability between the studies in how they defined remission.
Based on 17 studies, there was a statistically significant better response rate with venlafaxine compared to SSRI, although the difference was likely to be clinically marginal (RR 1.06, 95% CI: 1.01, 1.12). There was evidence of moderate heterogeneity. When the studies were pooled in a random-effects model the RR was very similar, but the comparison was no longer statistically significant. There were significantly more dropouts due to adverse events in the venlafaxine group than the SSRI group (RR1.38, 95% CI: 1.08, 1.77). Over all the results of the pre-specified subgroup analyses did not alter these findings. The authors stated that there was no evidence of publication bias based on the funnel plot.