'The use of brief interventions adapted from motivational interviewing across behavioral domains: A systematic review': Comment

Comments on "Deterioration over time in effect of motivational interviewing in reducing drug consumption and related risk among young people" (see record 2005-04962-013) by McCambridge & Strang. McCambridge & Strang (2005) report that the effects of their brief intervention had disappeared by 12-month follow-up, and speculate that 'deterioration of effect is the most likely explanation'. Before reflecting on reasons, I would first question whether their effects had actually 'disappeared'. Their design compared a 1-hour motivational interview (MI) with an assessment-only control. From my perspective, the results from this study are surprising 12-month residual effects of one counseling session. Nevertheless, the between-group effects of brief MI do diminish over time. In a new meta-analysis of 72 clinical trials (Hettema, Steele & Miller, in press) we found that the mean effect size of MI averaged across all reported outcome variables was d=0.77 up to 1 month later, 0.39 for 1-3 months, 0.31 at 3-6 months, 0.30 in months 6-12 and 0.11 at follow-ups longer than 12 months. The McCambridge & Strang findings are consistent with this trend. (PsycINFO Database Record (c) 2010 APA, all rights reserved)