Incentive payments increased quit rates among low-income smokers in Switzerland

The study, conducted in Geneva, Switzerland, enrolled 805 low-income smokers who indicated they were motivated to quit. Researchers randomly assigned 401 participants to the incentive group and 404 to a control group, verifying smoking status with biochemical tests throughout the study.

Limitations of the study were that a larger portion of the 81 participants who dropped out were in the control group than in the incentive group. Participants who dropped out or were missing data were counted as smokers. Also participants in the control group knew they were recruited to a study where some participants would receive incentive payments; and control group participants were subjected to fewer biochemical tests to verify status, which could have impacted behavior.

All participants in the study were provided booklets and access to a website with information about smoking cessation were given biochemical tests at the outset to confirm they were smokers. The incentive group received frequent rewards for confirmed abstinence, with rewards increasing incrementally after three months. Total incentives were worth as much as $1,500.

Previous research has shown smaller incentives helped smokers remain abstinent for six months after final incentive payments when research subjects were educated, relatively affluent employees of U.S. companies with access to counseling and other assistance. Researchers, led by Jean-François Etter, PhD, from the Institute of Global Health, University of Geneva, Switzerland, set out to find out if larger, incremental rewards would work better among lower income smokers who did not have access to other smoking cessation support.

Participants had a median income of about $20,000, and smoked about 16 cigarettes a day, with 43 percent identified as students, and 19 percent unemployed.

At three months, 44.4 percent of the smokers in the incentive group reported they had been abstinent continuously compared to 6.4 percent of the control group. At six months, 35.9 percent of the incentive group and 5.7 percent of the control group reported continuous abstinence. At each stage, biochemical tests confirmed abstinence for seven days and for four weeks.

At 18 months, which was one year after incentive payments ended, 9.5 percent of the incentive group and 3.7 percent of the control were confirmed abstinent.

With a difference of 5.76 percentage points between the control and the incentives group after 18 months, 17 people would need to go through an incentive program like the one in the study to get one person to quit. In an accompanying editorial, Joseph A. Ladapo, M.D., PhD, and Judith J. Prochaska, PhD, MPH, noted this means it would cost $28,050 to yield one additional long-term quitter.