Twenty-six RCTs reported in 29 publications (n=4,502 participants as reported in the table presented), range 23 to 786) were included. Nineteen trials were judged to be at low risk of bias in terms of sequence generation, nine in terms of allocation concealment and 17 in terms of incomplete outcome data. Five trials were rated as low risk of bias on all three domains. Sixteen studies performed an intention-to-treat analysis and four performed a quasi-intention-to-treat analysis. Three trials reported long-term follow-up of 32 weeks or 12 months.
Depression (eight RCTs, n=2,873): Six trials reported positive effects for CBT compared to control. The two trials that did not show beneficial effects used a psycho-education control group; one other trial that used a psycho-education control group reported beneficial effects. Effect size differences ranged from 0.30 to 0.53 for prevention or quasi-prevention trials and from 0.42 to 0.65 for patients with clinically significant symptoms. Two trials that reported follow-up of 12 months reported continued beneficial effects.
Anxiety (16 RCTs, n=1,318): All trials reported a significant positive result on at least one outcome measure. Effect size differences ranged from 0.29 to 1.74 and most exceeded 0.65.
Depression and anxiety interventions (two RCTs, n=311): One RCT reported an overall beneficial effect. Effect size differences ranged from 0.07 to 0.64.