Effectiveness of a low-intensity intra-worksite intervention on smoking cessation in Japanese employees: a three-year intervention trial.

To test the effectiveness of a low-intensity intervention program for smoking cessation targeting the worksite environment in employees who had a low readiness to quit, we conducted an intervention trial at six intervention and six control worksites in Japan. A total of 2,307 smokers at baseline who remained at their worksite throughout the three-year study period were analyzed (1,017 in intervention and 1,290 in control groups). The multi-component program at the worksites consisted of (1) presenting information on the harms of tobacco smoking and the benefits of cessation by posters, websites, and newsletters; (2) smoking cessation campaigns for smokers; (3) advice on designation of smoking areas; and (4) periodic site-visits of the designated smoking areas by an expert researcher. At baseline, the intervention and control groups each had high prevalence of immotive or precontemplation, that reflected low readiness to quit (71.5% and 73.2%, respectively). The smoking cessation rate, as not having smoked for the preceding six months or longer, assessed at 36 months after the baseline survey by a self-administered questionnaire was significantly higher in the intervention group than the control group (12.1%, vs. 9.4%, p=0.021). The intervention program still had a significant effect on the smoking cessation rate after multiple logistic regression analysis adjusted for sex, age, type of occupation, age of starting smoking, quit attempts in the past, number of cigarettes per day, and readiness to quit (odds ratio: 1.38, 95% confidence interval: 1.05-1.81, p=0.02). The cost per additional quitter due to the intervention was calculated to be Yen 70,080. These findings indicate that this program is effective and can be implemented in similar workplaces where the prevalence of smoking is high and smokers' readiness to cease smoking is low.