Lessons from large trials: the MTA study as a model for evaluating the treatment of childhood psychiatric disorder.

OBJECTIVE: To review the methodology of the Multimodal Treatment Study of Children With Attention-Deficit Hyperactivity Disorder (ADHD), the MTA study, and its implications for the design of future child mental health treatment studies.
METHOD: The characteristics of large-scale studies envisioned by trialists engaged in cardiovascular and cancer research provide the framework for reviewing key elements of the MTA study--objectives, research questions, measurement, sampling, and exposure to treatment--and discussing important methodological decisions the MTA investigators had to make.
RESULTS: The MTA study is a complex, standardized, carefully implemented, randomized control trial. Review of the MTA study indicated that future studies should be aligned clearly with either effectiveness or efficacy objectives but not both. Questions selected for study should be simple, clear, and important. Measurement, sampling, and data collection must adhere to the principle of simplicity to ensure maximum participation. All methodological decisions should be geared to attaining the research objectives: in effectiveness trials, this means evaluating treatments that have a high potential for dissemination if proven successful and recruiting only new referrals from child mental health settings.
CONCLUSIONS: The MTA study has raised the standard for technical excellence in child treatment research and will draw attention to some fundamental issues in large-scale child treatment studies, including articulating objectives and questions, setting priorities for measurement and sampling, and identifying treatments for evaluation that have a high probability of dissemination if found effective.