Thirty-three studies (7,690 participants) were included in the review: 29 randomised controlled trials (RCTs), two non-randomised between-group studies and two non-randomised single group pre- and post-test studies. Sample sizes across the studies ranged from 10 to 1,578 patients. Post-treatment assessments were conducted from two weeks to 52 weeks post intervention.
Small but statistically significant benefits of the eHealth interventions were observed across all trials (d=0.118, 95% CI 0.066 to 0.171; 33 studies) with significant heterogeneity across the results (Q=62.851, p<0.001).
Effect sizes for the interventions that incorporated behavioural components were also small and statistically significant (d=0.354, 95% CI 0.232 to 0.475; 20 studies). There were no significant differences between educational eHealth interventions and control treatments (d=0.033, 95% CI 0.037 to 0.103; 13 studies). The reviewers stated that the Q statistics within each of the behavioural and educational interventions did not suggest statistically significant heterogeneity.
The fail safe n size calculation was that 230 studies with null findings were required to negate the observed findings.