Primary outcome indices in illicit drug dependence treatment research: Systematic approach to selection and measurement of drug use end-points in clinical trials.

Clinical trials test the safety and efficacy of behavioral and pharmacological interventions in drug-dependent individuals. However, there is no consensus about the most appropriate outcome(s) to consider in determining treatment efficacy or on the most appropriate methods for assessing selected outcome(s). This paper summarizes the discussion and recommendations of a panel of treatment and research experts, recently convened by the U.S. National Institute on Drug Abuse (NIDA) to select appropriate primary outcomes for drug dependence treatment clinical trials, including the National Drug Abuse Treatment Clinical Trials Network (CTN), and examine the feasibility of selecting a common outcome to be included in all or most trials (a paper from a second panel at the same meeting presents an overview of previous recommendations and outlines specific guidelines for consideration in candidate outcomes — see Tiffany et al, 2012). A brief history of outcomes employed in prior drug dependence treatment research, incorporating perspectives from tobacco and alcohol research, is included.

Conclusions: The panel reached consensus that the primary outcome measure should be an indicator of drug-taking behavior, and that there is no single clinical metric that is appropriate for inclusion in most drug dependence treatment trials. The panel noted that a wide variety of indicators are available, the most appropriate one varying by study methods and goals (e.g. abstinence or reduction of use). It is recommended that a decision process, based on such trial variables, be developed to guide the selection of primary and secondary outcomes as well as the methods to assess them.

Update: Commentary about this article and a related article by Stephen Tiffany (see item 793), with responses from Drs. Donovan and Tiffany, was published in Addiction 2012;107(4):719-726.