Lottery incentives for smoking cessation at the workplace: a cluster randomized trial

Smoking is the largest behavioral risk factor for loss of healthy life years. Many smokers intend and try to quit, but have trouble realizing their behavioral health goals. When workplace cessation-support is accompanied by incentives, this can increase its effectiveness. Based on principles from behavioral economics and psychology, regret lotteries have supported the realization of other health behaviors. Regret lotteries capitalize regret aversion by always informing winners at the deadline, but withholding prizes if they smoked. This study builds on previous applications of regret lotteries to test its potential, using a novel combination of incentives, the workplace as a context and smoking as the target behavior.

We compared a workplace group cessation training (control arm) to the same training plus regret lotteries (intervention arm). To test its effect on smoking cessation, we performed a cluster randomized trial with 13 organizations and 111 participants, followed for 52 weeks. Participants in the intervention arm additionally participated in 13 weekly lotteries, followed by a long-term lottery after 26 weeks. In each lottery, winners were drawn from all participants in a group. Winners were promised to always learn the outcome of the lotteries. However, the winners could only claim their prize if they did not smoke. The primary outcome of interest was continuous smoking abstinence at 52 weeks from the quit date, self-reported and biochemically validated with a carbon monoxide measurement and a cut-off point of ≤ 9 parts per million. A multi-level logistic regression analysis was performed to estimate the treatment effects after 52 weeks, while accounting for the clustered data pattern within organizations. We adjusted for Fagerström nicotine dependence score, education level, income, age and gender. Secondary outcomes were abstinence at weeks 13 and 26 after the quit-date.

At the 52-week primary outcome point of this trial, in the control arm, 23.9% of participants were continuously abstinent opposed to 43.2% in the intervention arm (OR = 3.25; 95% CI, 0.99-10.70). Thirteen weeks after the quit date, in the control arm, 35.8% of participants were continuously abstinent opposed to 68.2% in the intervention arm (OR = 3.66; 95% CI, 1.47-9.16). After 26 weeks, in the control arm, 25.4% of participants were continuously abstinent opposed to 54.6% in the intervention arm (OR = 3.24; 95% CI, 1.27-8.22).

Although differences were only statistically significant up to 26 weeks, we found meaningful and practically relevant increases in smoking cessation due to the lottery intervention at the main outcome point. The intervention design was rooted in behavioral economics and builds on previous successful applications. Therefore, the results show enough potential to theorize and further apply this method in a field setting, that can benefit from the theoretical, methodological and practical lessons learned in this trial.

The trial protocol and materials were reviewed and approved by the Radboud University Ethical Review Board (ECSW-2019-114). The study was registered in the Dutch Trial Register (trial registration number: NTR NL84632, 17 March 2020) and lottery drawings were performed by an independent notary.