Nationwide access to an internet-based contingency management intervention to promote smoking cessation: a randomized controlled trial

Background and aims: Contingency management (CM) is one of the most effective behavioral interventions to promote drug abstinence, but availability of this treatment is limited. We evaluated the efficacy and acceptability of internet-based CM relative to an internet-based monitoring and goal-setting control group in a nationwide sample of cigarette smokers. Design: Randomized controlled trial with 3- and 6-month follow-ups. Setting: United States. Participants: Smokers (n = 94) from 26 states were enrolled (mean age 36, 56% female). Intervention and comparator: Participants were randomized to earn financial incentives (up to $480 over 7 weeks) based on video-verified abstinence using breath carbon monoxide (CO) output (n = 48; abstinent contingent group, AC), or based on submitting CO samples (n = 46, submission contingent, SC). Both groups also received the same CO-based goals. A $50 deposit was required in both groups that could be recouped from initial earnings. Measures: The primary outcome was point prevalence at week 4. Secondary outcomes were point prevalence at the 3- and 6-month follow-ups, percentages of negative CO samples, adherence to the CO sampling protocol, and treatment acceptability ratings on a 0–100-mm visual analog scale. Findings: Abstinence rates differed at 4 weeks between the AC (39.6%) and SC (13.0%) groups [odds ratio (OR) = 4.4, 95% confidence interval (CI) = 1.6–12.3], but not at the 3- (29.2% AC and 19.6% SC, OR = 1.7, 95% CI = 0.6–4.4) or 6- (22.9% AC and 13.0% SC, OR = 2.0, 95% CI = 0.7–5.9) month follow-ups. During the two main treatment phases, there were significant differences in negative COs (53.9% AC and 24.8% SC, OR = 3.5, 95% CI = 3.1–4.0; 43.4% AC and 24.6% SC, OR = 2.3, 95% CI = 1.6–3.4). Adherence to the CO submission protocol was equivalent (78% AC and 85% SC, difference = 7.0%, 95% CI = −10.3 to 23.8 %, F < 1, P = 0.39). The lowest acceptability ratings were for the items assessing the deposit, whereas the highest ratings concerned the ease of the intervention, the graph of CO results, and earning money. Conclusions: A contingency management/financial incentive program delivered via the internet improved short-term abstinence rates compared with an internet program without the incentives.