Methods: A random effects meta-analysis was conducted with RCTs of CBT published from January 1, 2000 – December 31, 2009. Forty-nine studies (k=49) that treated children and adolescents with anxiety or mood disorders were analyzed. Information obtained from CBT intervention studies included demographic characteristics (age, gender, race), intervention characteristics (treatment modality, number of sessions, session length in minutes), booster session characteristics (number of booster sessions, time to each booster session), outcome measures, and pre-test/post-test means and standard deviations. Authors and trained research assistants coded data from each article, yielding an inter-rater agreement (>95%) among them. Cohen's d (with CI and I2) was calculated for pre-test/post-test change for each outcome and then yielded a single effect size per study by averaging across outcomes.
Results: Results show that overall CBT treatment of internalizing disorders for youth had large effects on study outcomes (k=49, d=0.90). Specifically, CBT for anxiety disorders yielded larger effects (k=37, d=0.94), whereas CBT for mood disorders showed smaller effects (k=12, d=0.81). However, studies with booster sessions exert substantially larger effects (k=14, d=1.19) than those without booster sessions (k=35, d=0.84). Interaction results found differing effects of booster sessions by demographic and intervention characteristics. Among studies with booster sessions youth from 10 to 13 years-of-age showed 20% larger effects than children (0 to 9 years-of-age) or teens (14 to 17 years-of-age). In studies with more male participants (67% to 100%), booster sessions yielded 20% larger effects than were female-dominated studies (67% to 100%). The interaction of booster sessions by number of sessions (median of 12) evidenced a bimodal distribution, with below and above median categories having higher effects than the median category. A linear trend was detected in the interaction of booster sessions by session length in minutes, showing increasing effects as number of session length increased. Also, in the interaction of booster sessions by intervention modality, effects of family and group modalities were 20% smaller than individual treatment and 50% smaller than mixed treatment. All effect sizes were statistically significant (p<.05).
Implications: Findings can assist in the individual tailoring of CBT interventions for children and adolescents by incorporating booster sessions on according to specific client mental illness presentation and demographics. Overall, findings show that using booster sessions increases the effects of CBT on youth. Booster sessions are therefore recommended for CBT interventions for youth with anxiety and mood disorders. Clinical, research, and policy implications will be explored.
