Effectiveness of motivational interviewing in smoking groups in primary healthcare: a community-based randomized cluster trial

Smoking is the main cause of avoidable death and a major public health problem worldwide, with primary healthcare being a strategic setting for treating this problem. Aims: to evaluate the effectiveness of motivational interviewing associated with the cognitive behavioral therapy (CBT) in smoking groups in primary healthcare. A community-based cluster randomized clinical trial was conducted in Brazil, starting in July 2016. Professionals in the test group were trained in motivational interviewing for eight hours to associate it with the CBT. The usual treatment for smoking cessation in groups consists of four structured weekly sessions of 90 minutes each using a CBT. Taylor's linearization was used to correct the p-values; the chi-square test with Pearson correlation was used for categorical variables, and analysis of variance as well as the Student t-test were used for continuous variables. In total, 44 smoking groups were conducted, totaling 329 patients (178 in the motivational interviewing group and 151 in the control group). The smoking cessation rate with motivational interviewing was 61.8%, with RR = 1.25 (95%CI: 1.01-1.54, p = 0.043), and 47.7% in the control group, in the fourth weekly group treatment session. Mean session attendance was 3.1 (95%CI: 2.9-3.3) in the motivational interviewing group and 2.9 (95%CI: 2.5-3.4) in the control group. The completion rate for the motivational interviewing group was 65.2% and for the control group, 57.6%. Motivational interviewing associated with the CBT was shown to be effective and superior to only CBT to smoking cessation in groups in the fourth weekly session and for the population profile of the study (women with an average age of 50.6 years).