Youth psychotherapy outcome research: a review and critique of the evidence base.

Over the past four decades, researchers have produced extensive evidence on psychotherapy for youth mental health problems and disorders. The evidence often has been evaluated through narrative reviews and through meta-analyses assessing the magnitude of treatment effects, but methodological analysis addressing the character and quality of the evidence base itself is an important complement, needed to place treatment effects in perspective and to suggest directions for future research. We carried out such an analysis, focusing on all the methodologically acceptable published randomized trials our search identified involving treatment of anxiety, depression, ADHD and related conditions, and conduct-related problems and disorders. The 236 studies tested 383 treatments and included 427 treatment-control comparisons, spanning the years 1962 through 2002. The analysis revealed considerable breadth, diversity, and rigor in the measurement approaches used to assess participant characteristics and treatment outcomes. However, reporting on important sample characteristics (e.g., ethnicity) showed major gaps, and more than half the studies failed to use well-standardized procedures to ensure appropriate sample selection. Because sample sizes left most studies underpowered, and procedures to enhance treatment fidelity were generally weak, many of the treatments investigated may not have received fair tests. Studies were particularly weak in clinical representativeness of their samples, therapists, and settings, suggesting a need for increased emphasis on external validity in youth treatment research.