Effectiveness of the Brief Guided Self-Change Therapy Combined with Varenicline under "Real-Life" Conditions and Mediators for Smoking Cessation.

Background: Brief therapies have proven to reduce tobacco cost-effectively, however, unsuccessful quit attempts remain notable in real-life conditions, and the underlying mechanisms of treatment success are still unclear. Objectives: We aimed to analyze the effectiveness of the Guided Self-Change (GSC) therapy combined with varenicline (VAR+T) in public health services against varenicline alone (VAR), and to identify mediators of treatment outcomes. We conducted a two-arm quasi-experimental study with 126 treatment-seeking smokers (age=57.3±9.1 years; 59.5% women). Before treatment, and at weeks 12 and 24, we assessed tobacco use and five potential mediators: withdrawal, craving, motivation to quit, anxiety, and depression. Results: Only 25% of participants adhered to varenicline prescription, and 54% to GSC therapy. VAR+T group showed a greater proportion of abstainers compared to VAR group at week 12 (75% vs 57.4%; φc=0.21) and week 24 (62.9% vs 52.5%; φc=0.10). When controlling for weeks taking varenicline, motivation showed a significant indirect effect over abstinence rates in VAR+T compared with VAR (a1b1=1.34; 95%CI=0.04, 5.03). Conclusions: The GSC effectiveness seems to increase motivation which in turn contributes to reducing tobacco use. The implementation of GSC therapy in public health services could minimize treatment duration and increase smoking abstinence in 'real-life' conditions where varenicline adherence remains low.