Commitment contracts and team incentives: a randomized controlled trial for smoking cessation in Thailand

Abstract

Background: Treatment for tobacco dependence is not available in many low-resource settings, especially in developing countries.

Purpose: To test the impact of a novel mix of monetary and social incentives on smoking abstinence in rural communities of Thailand.

Design: An RCT of commitment contracts and team incentives for rural smokers to quit smoking. Smokers were not blinded to treatment status, although the assessor of the biochemical urine test was.

Setting/participants: All adult smokers living in the study area were eligible to participate; 215 adult smokers from 42 villages in Nakhon Nayok province, Thailand, participated. Fourteen smokers who lacked teammates were dropped.

Intervention: A total of 201 smokers were assigned to a two-person team, and then randomly assigned by team (in a 2:1 ratio) with computer-generated random numbers to receive smoking-cessation counseling (control group) or counseling plus offer of a commitment contract, team incentives, and text message reminders for smoking cessation at 3 months (intervention group).

Main outcome measures: The primary outcome was biochemically verified 7-day abstinence at 6 months, assessed on an intention-to-treat basis. Secondary outcomes include study participation, biochemically verified abstinence at 3 months, self-reported abstinence at 14 months, and the incremental cost per quitter of the intervention, nicotine gum, and varenicline in Thailand. Data were collected in 2010-2011 and analyzed in 2012.

Results: The trial enrolled 215 (10.5%) of 2055 smokers. The abstinence rate was 46.2% (61/132) in the intervention group and 14.5% (10/69) in the control group (adjusted OR 7.5 [3.0-18.6]) at 3 months; 44.3% (58/131) and 18.8% (13/69) at the primary end point of 6 months (adjusted OR 4.2 [1.8-9.7]); and 42.0% (55/131) and 24.6% (17/69) at 14 months (adjusted OR 2.2 [1.0-4.8]). The purchasing power parity-adjusted incremental cost per quitter from the intervention is $281 (95% CI=$187, $562), less than for nicotine gum ($1780, 95% CI=$1414, $2401) or varenicline ($2073, 95% CI=$1357, $4388) in Thailand.

Conclusions: The intervention enhanced abstinence by 91%-136% at 6 months, relative to the control group, although self-reports at 14 months suggest tapering of the treatment effect. The intervention may offer a viable, cost-effective alternative to current smoking-cessation approaches in low-resource settings.

Trial registration: This study is registered at ClinicalTrials.gov NCT01311115.

Figure 1

Study profile

Figure 2

Predicted probability of smoking abstinence, by month and treatment status

Figure 3

Incremental cost per quitter, by type of intervention Thai, Thailand; Sing., Singapore