Efficacy and effectiveness issues in the NIDA Cooperative Agreement: interventions for out-of-treatment drug users....

This paper examines the Cooperative Agreement (CA) HIV intervention studies for active drug users, sponsored by the National Institute on Drug Abuse, in terms of the constructs of prevention efficacy and effectiveness. A rationale is presented for conservatively interpreting outcome findings of these studies as indicative of intervention efficacy, as opposed to effectiveness. It is argued that the CA studies fall more within the domain of efficacy owing to the high degree of control and optimization that occurred with respect to intervention recruitment, participation, process monitoring, and staff training. Because the interventions were implemented and evaluated in community-based, noninstitutional settings with many real-world constraints, it is suggested that minimal shrinkage of their effects would occur if they were implemented in uncontrolled community settings. The relationship of intervention structure, content, process, dose, and participant characteristics to intervention efficacy is reviewed and discussed, both in general terms and with reference to the CA studies.