A systematic review including 12 studies with a total of 2334 subjects was abstracted in DARE. There was a significant difference in effect size (ES) in favour of internet-based CBT compared with control (random-effects model, ES 0.51, 95% CI: 0.28, 0.74). A pooled analysis of the 2 prevention studies (n=352) showed no significant difference between intervention and control. Heterogeneity between the 10 treatment studies was statistically significant and the ES in favour of internet-based CBT remained significant.
Comment: The quality of evidence is downgraded by inconsistency (variability in results across studies) and limitations in review methodology.