Beyond “planning”: A meta-analysis of implementation intentions to support smoking cessation.

Objective: Implementation intentions support behavior change by encouraging people to link critical situations with appropriate responses. Overall effectiveness for smoking cessation is unknown. This systematic review and meta-analysis aimed to evaluate the effectiveness of implementation intentions for smoking cessation. Method: Using PRISMA guidelines, 6 electronic databases were searched (updated February 2018) using key terms. Data were pooled for smoking cessation (categorical variable; yes/no) and entered into random effects models. Analyses assessed: (a) effectiveness as a single intervention, and (b) effectiveness when included as one of multiple intervention components. Results: Twelve studies were identified. Implementation intentions were effective for smoking cessation at follow up, OR = 1.70, CI [1.32, 2.20], p < .001, average 10.7% quit rate for intervention participants (4.9% in controls). Implementation intentions as a single intervention were effective for smoking cessation, OR = 5.69, 95% CI [1.39, 23.25], p = .02 (average quit rate 14.3% in intervention participants vs. 3.6% in controls) and as part of multicomponent interventions, OR = 1.67, 95% CI [1.29, 1.66], p < .001 (average quit rate 8.2% in intervention participants vs. 5.8% in controls). Conclusions: Implementation intentions are effective at helping smokers quit although the review reported substantial heterogeneity across the limited number of included studies. The present review sets the agenda for future research in this area including longer term objectively verified abstinence and identification of potential moderators of effectiveness including population characteristics.