LAUSR

AIMS To determine whether mechanisms of drinking behavior change that are targeted by specific treatments mediate the effects of Packaged Cognitive Behavior Therapy (PCBT) and Network Support (NS) on abstinence rates throughout 27 months. DESIGN Secondary analysis of data from two Network Support Project randomized clinical trials, in which participants were assigned to either a case management control treatment (control) or NS treatment in trial 1, or to PCBT or NS treatment in trial 2. SETTING An out-patient substance abuse treatment site at a university medical center in the United States. PARTICIPANTS A total of 249 men and 154 women (n = 403) with alcohol use disorder. MEASUREMENTS The primary outcome was membership in a treatment responder class determined by growth mixture modeling (GMM) of monthly proportion days abstinent (PDA) to 27 months. Key predictors of responder class membership included network change variables, and changes in coping scores and self-efficacy. FINDINGS GMM analyses indicated that a three-class solution provided the best fit to the data: a treatment responder class comprising almost 55% of patients, a late relapsing class that showed post-treatment gains followed by a return to baseline drinking (12.7% of patients) and a non-responder class (32% of patients). Analyses indicated that treatment effects on responder class membership were moderated by baseline drinking (P < 0.001). PCBT effects were mediated by changes in coping scores (P < 0.05). NS treatment effects were also mediated by coping change, as well as by increases in self-efficacy and in number of abstinent friends (P < 0.05). CONCLUSIONS Long-term success in Packaged Cognitive Behavior Therapy and Network Support treatments for alcohol use disorder appears to be mediated by both general mechanisms (developing coping skills and self-efficacy) and treatment-targeted mechanisms (developing network strategies that emphasize social support and avoiding friends who drink).