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A Randomized Controlled Trial for Smoking Cessation in Thailand

Development Challenge

A disproportionate portion of tobacco-related mortality occurs in the developing world. Of the one billion smokers in the world, nearly 80 percent live in developing countries.[1] And while rates of smoking have plateaued or declined in the developed world, tobacco consumption in developing countries is rising by approximately 3.4 percent annually.[2] Standard treatments for tobacco dependence – nicotine replacement therapy, prescription drugs, and professional counseling – are not widely available in low-resource settings. Previous studies indicate voluntary commitment contracts can improve smoking cessation programs. However, few studies have analyzed the effects of commitment contracts that incorporate social pressure into their design. 


In Thailand, 45.6 percent of adult men and 3.1 percent of adult women still smoke despite the existence of strongly enforced smoking laws that prohibit smoking in public places and regulate tobacco promotion.[3] Due in part to these policies, there is a rising demand to quit smoking. This study used a randomized controlled trial to examine the impact of monetary and social incentives on a smoking cessation program in Thailand's Nakhon Nayok province, which has an adult smoking prevalence rate of 23 percent for men and 2 percent for women.

Evaluation Strategy

The evaluation included 42 villages in six sub-districts of Nakhon Nayok province. All participants had to be smokers and at least 20 years old. 201 individuals – approximately ten percent of those eligible – were randomly sorted into two-person teams, with 66 teams randomly assigned to the treatment group and 28 teams assigned to the comparison.

In the treatment group, each individual opened a commitment savings account with a minimum balance of USD 1.67. The project added an additional USD 5 starter contribution to the account. Participants could deposit money to the savings account on a weekly basis and the project provided a USD 5 bonus if at least USD 5 were deposited during the allotted period. The deposits and matching contribution were refunded conditional on the participants abstaining from smoking after three months. If both team members abstained, each received a bonus of USD 40. This second bonus induces peer pressure for each participant to individually commit. The project sent weekly text messages to encourage deposits and monitor participants. The comparison group only received counseling before treatment assignment and at three months.

At three months, participants confirmed they quit smoking through self-reports and urine tests. Urine tests were also conducted after six months, and self-reported results were collected between 12 and 15 months (denoted below as 14 months). Outcomes of interest include abstinence from smoking and the marginal cost per quitter of the intervention.

Results and Policy Implications

The intervention increased abstinence rates in the treatment relative to the comparison groups at three, six, and 14 months after the treatment date. Abstinence rates for each group are listed in the table below:

Months after treatment date:












The study also collected data on the incremental cost of the intervention per quitter. At USD 281 per quitter, the intervention is less expensive than nicotine gum (USD 1,780) and varenicline, a common prescription medication, (USD 2,073) indicating that contracts may be a more cost-effective approach to smoking cessation in developing countries. These results highlight the potential of commitment contracts that include social incentives to curb smoking and prevent relapse.  Further research should be done to determine whether the effect persists over time.



[1]Tobacco Fact Sheet. (2014, May). World Health Organization. Retrieved from

[2] Smoking Statistics. (2002, May 28). World Health Organization. Retrieved from

[3] Benjakul, S., Termsirikulchai, L., Hsia, J., Kengganpanich, M., Puckcharern, H., Touchchai, C.,  & Asma, S. (2013). Current manufactured cigarette smoking and roll-your-own cigarette smoking in Thailand: findings from the 2009 Global Adult Tobacco Survey. BMC public health, 13(1), 277.

Photo Credit: Reuters/Sukree Sukplang, Bangok 2007.