Multisite effectiveness trials of treatments for substance abuse and co-occurring problems: Have we chosen the best designs?

Multisite effectiveness trials such as those carried out in the National Drug Abuse Treatment Clinical Trials Network (CTN) are a critical step in the development and dissemination of evidence-based treatments because they address how such treatments perform in real-world clinical settings. Several possible experimental designs may be chosen for such effectiveness trials. These include (a) a new treatment intervention (Tx) is compared to an existing mode of community based treatment as usual (TAU): Tx versus TAU; (b) a new intervention is added to TAU and compared to TAU alone: Tx + TAU versus TAU; or (c) a new intervention is added to TAU and compared to a control condition added to TAU: Tx + TAU versus control + TAU. Each of these designs addresses a different question and has different potential strengths and weaknesses. As of December 2009, the primary outcome paper had been published for 16 of the multisite randomized clinical trials conducted in the CTN, testing various treatments for drug abuse, HIV risk behavior, or related problems.

This paper systematically examines, for each of the completed trials, the experimental design type chosen and its original rationale, the main findings of the trial, and the strengths and weaknesses of the design in hindsight. Based on this review, recommendations are generated to inform the design of future effectiveness trials on treatments for substance abuse, HIV risk, and other behavioral health problems. Addressing the right questions, looking closely at effect size and power, as well as internal versus external validity, and more consideration for three-arm designs and cost-effectiveness will serve well the goals of effectiveness research.

Related protocols: CTN-0001, CTN-0002, CTN-0003, CTN-0004, CTN-0005, CTN-0006, CTN-0007, CTN-0009, CTN-0010, CTN-0011, CTN-0013, CTN-0015, CTN-0017, CTN-0018, CTN-0019, CTN-0021