People experiencing homelessness have a 3.5-fold higher prevalence of cigarette smoking in comparison to non-homeless people, contributing to 2-fold higher rates of lung cancer and 3- to 5-fold higher rates of tobacco-attributable death. Homeless smokers want to quit, but studies have not yet uncovered the optimal approach to help them do so. In an 8-week pilot randomized controlled trial (RCT) at Boston Health Care for the Homeless Program (BHCHP), we found that financial incentives for smoking abstinence were associated with 7-fold higher odds of brief smoking abstinence in comparison to a non-incentivized control condition. These results suggest that financial incentives are a promising approach for reducing smoking in this vulnerable population, but further investigation in a larger sample is needed to improve the duration of on-treatment abstinence, assess post-treatment effects, and better understand mechanisms of action and contextual factors that may influence treatment response.~To address the above gaps in evidence, we will conduct a community-based RCT of financial incentives for smoking abstinence among adult smokers at BHCHP. Recognized as a leader in homeless health care, BHCHP serves 12,000 currently and formerly homeless patients annually throughout greater Boston. We will randomize 400 participants recruited from 3 BHCHP sites: a shelter clinic, a day center clinic, and a medical center clinic. All participants will be offered 12 weeks of varenicline, 5 sessions of tobacco coaching, and 10 cotinine monitoring visits over a 12-week period. Participants randomized to the financial incentives arm (n=200) will receive escalating debit card payments (range $25-$70) at each monitoring visit for saliva cotinine levels <30 ng/ml. Control arm participants (n=200) will receive a fixed payment ($10) at each monitoring visit regardless of their saliva cotinine level. We will use an embedded-experiment mixed methods design, where qualitative ('qual') data collection is embedded within a larger quantitative ('QUAN') RCT with the following specific aims:~Aim 1. (QUAN) To determine the effect of the financial incentives intervention on cotinine-verified 7-day smoking abstinence at A) the end of treatment (12 weeks) and B) 12 weeks after treatment (24 weeks).~Hypotheses: Incentive arm participants will have significantly greater cotinine-verified 7-day smoking abstinence than control arm participants at A) 12 weeks and B) 24 weeks.~Aim 2. (qual) To assess why, how, and under what circumstances homeless smokers A) achieve abstinence in response to financial incentives and B) maintain abstinence after incentives are stopped.~Interviews with participants at A) 12 weeks (N=30) and B) 24 weeks (N=20) will examine cognitive ('why?'), procedural ('how?'), and contextual ('under what circumstances?') dimensions of their response to financial incentives to generate hypotheses about potential mechanisms for on-treatment and post-treatment effects and to inform modifications of the intervention for future use.
This community-based randomized controlled trial will test the effect of contingent financial rewards on smoking abstinence among homeless-experienced adult cigarette smokers. Participants will be recruited from 3 Boston Health Care for the Homeless Program locations: a shelter clinic, a day center clinic, and a medical center clinic. All participants will be offered a varenicline prescription and tobacco coaching. Incentive arm participants will receive escalating financial rewards for saliva cotinine levels <30 ng/ml, assessed 10 times over 12 weeks. Embedded qualitative interviews will explore the mechanisms of on-treatment and post-treatment effects of financial incentives on smoking abstinence in the context of homelessness.