Forty-four studies were included in the review: thirty-nine RCTs and five controlled trials. Jadad scores were zero (four studies), 1 (22 studies), 2 (16 studies) and 3 (two studies).
Anxiety studies (18 trials, 20 comparisons): Approximately 60% of the trials were associated with a positive outcome. Effect sizes ranged from 0.57 to 1.09 in 11 universal trials and 0.02 to 0.48 in six selective and one joint selective and indicated trial.
Depression studies (26 trials, 30 comparisons): Approximately 63% of the comparisons were associated with a positive outcome. Significant results for positive depression outcomes were reported in five out of six universal comparisons (effect size 0.50 to 0.75), nine out of 19 selective comparisons (effect size 0.27 to 0.90), all three indicated comparisons (effect size 0.23 to 0.65) and both of the selected and indicated comparisons (effect size 0.47 to 1.50).
Results for relevance of intervention and at follow-up were reported.