Methods: A random effects meta-analysis was conducted with published RCTs of cognitive behavioral therapy, interpersonal therapy, and psychoeducation for child and adolescent mental health disorders published from January 1, 2000 – December 31, 2007 (k=98). Cohen's d was calculated for pre-test/post-test change for each intervention reported. As published articles commonly do not report adherence promoting interventions, an electronic survey of adherence promoters was sent to the first authors of the published studies. The survey asked respondents to describe their use of 8 different adherence promoting intervention strategies: telephone, mail, other technology assisted contacts, concrete assistance, motivational enhancement interviews, incentives, other therapeutic interventions, and other intervention types. Forty seven surveys were completed (48%). Results of this survey, along with other study characteristics coded from the original research reports, were treated as potential moderators of treatment effect. Weighted least squares regression (inverse sampling error variance) was used to test for moderators.
Results: 81% of the studies included at least one CBT condition. The average sample size was 156 (S.D.=282). 50% of the sample subjects were male and their average age was 12.6 (S.D.=3.15). Across all outcomes, the sample weighted pre-test/post-test average effect size was .64 (S.D.=.76); the sample weighted pre-test/post-test average effect size for mental health outcomes was .72 (S.D.=.80). Preliminary analysis indicated that less than 1% of the variance was accounted for by sampling error. Multivariate WLS analysis indicated that three variables moderated the effect size (r2=.64): group format vs. other format type (B=-.704, p<.001), number of total types of promoters utilized (B=-.283, p<.001), and average length of time in minutes devoted to promoters during each session (B=.018, p<.01). Of individual promoters, only pre-treatment motivational enhancement interventions moderated effect sizes (B=.482, p<.01).
Conclusions and Implications: Results of the study are suggestive that adherence promoting interventions improve client outcomes. RCTs that devoted more time to intervention adherence per session and that employed pre-treatment motivational enhancement interventions had higher effect sizes than interventions that do not utilize these strategies. Findings of this study suggest that adherence promotion should be systematically addressed in EBPs for child and adolescent mental health problems. Methodologically, this study demonstrated that surveys of study authors are a promising approach to measuring moderators not typically reported in RCT reports.