A new study comparing the effectiveness of smoking cessation strategies offers some insight on human behavior but little clear-cut guidance for employers and policymakers.

Smokers were significantly more likely to abstain from smoking for at least six months if they risked losing a $150 deposit. But few people were willing to put down the deposit in the first place, suggesting the strategy might be less valuable than ones that are otherwise less effective.

University of Pennsylvania researchers assigned individuals into five groups with different interventions. Some participants were offered $800 for abstaining from smoking. Another group had to put down the $150 deposit, which they would get back along with a reward of about $450 if they abstained from smoking. A third was offered “usual care,” which included informational materials and American Cancer Society guides.

The study, published Wednesday in the New England Journal of Medicine, had 2,538 participants, all of whom were adults over 18 who smoked at least five cigarettes a day and were either CVS Caremark employees or friends or family members of employees. The study was funded by CVS, the National Cancer Institute and the National Institute on Aging.

The 41% of participants with CVS health plan benefits also had access to free pharmacologic smoking-cessation aids and nicotine-replacement therapy.

Abstinence was measured at 14 days, 30 days and six months. After six months, 52.3% of those who put down the deposit were still abstaining from smoking compared with 17.1% in the reward category and just 6% in the usual-care group.

While it may appear that the deposit strategy was the most successful, only 13.7% of the smokers assigned to that group agreed to remain in the study. In comparison, 90% of smokers assigned to the reward group went along with it.

Cass Sunstein, a Harvard University law professor who served as a senior adviser to President Barack Obama and wrote a book called "Nudge" about behavioral economics, says the findings reflect people's general “loss averse” bias.

“They tend to dislike losses more than they like corresponding gains,” Mr. Sunstein wrote in an editorial accompanying the study in the New England Journal of Medicine. The deposit and reward strategies for smoking cessation, he said, are akin to having to pay a 5-cent tax on a grocery versus receiving a 5-cent bonus for bringing one's own bag.

Mr. Sunstein said the study illustrated the implications of using loss-aversion strategies in different ways. “The more obvious is that smokers are far more likely to quit if they stand to lose money if they fail,” he said. “The more subtle is that the very prospect of incurring losses makes people far less willing to enter a smoking-cessation program."

Mr. Sunstein suggested future research be done that tests whether a smaller deposit would increase participation without decreasing the effectiveness of the strategy.

CVS announced that it would start a new program, called “700 Good Reasons,” that would do just that. The program will require participants to put down a $50 deposit with the chance to earn up to $700 in rewards (along with the return of their deposit) if they abstain from tobacco for 12 months.

“The research we conducted with the University of Pennsylvania provided us with important information about what can motivate and help our colleagues stop smoking,” Lisa Bisaccia, CVS Health's executive vice president and Chief Human Resources Officer, said in a news release.

In the NEJM report, the University of Pennsylvania researchers also cited a study finding that employers sustain as much as $5,816 in additional costs for employees who are smokers because of absenteeism ($517), reduced productivity ($462), time lost during smoke breaks ($3,077) and — for self-insured employers — extra health care costs ($2,056).

The researchers conclude that it would be “highly cost-saving” for employers to invest $800 in a smoking-cessation effort. Reward-based programs, they conclude, were more effective than deposit-based programs because of their much higher rate of acceptance.

The researchers also found no significant difference in the abstinence rates between participants who worked together as a cohort and those who worked alone. Nor did the participants with access to free smoking-cessation aids have higher rates of success.

CVS discontinued sales of tobacco products at its stores last year. Last year also marked the 50th anniversary of the release of “Smoking and Health”, U.S. Surgeon General Dr. Luther Terry's report on the hazardous effects of smoking tobacco.

Andis Robeznieks writes for Modern Healthcare, a sister publication of Business Insurance.