Effectiveness of annual interventions for smoking cessation in an occupational setting in Japan

To examine the effectiveness of a small-scale smoking cessation intervention program conducted annually for ten years in an occupational setting in Japan. We conducted an annual intervention program promoting smoking cessation in male smokers from 1993 to 2002 in an occupational setting in Hyogo, Japan. Trends in smoking prevalence in this worksite were compared with a control group from two similar worksites of the same company. The intervention program was carried out by medical students (the fourth year of a six-year course) who received training on the protocol prior to the intervention. This protocol consisted of one initial group session, followed by periodical correspondence for two months. Successful cessation of smoking was determined by self-declaration of abstinence for longer than four weeks after intervention, confirmed by an expiratory carbon monoxide concentration of less than nine ppm. Smoking prevalence was determined by a self-administered questionnaire provided at the annual health checkup. The proportion of smokers who participated in the program was 3.47% on average. Abstinence rates following each intervention ranged from 13.3% to 60.0%, with the prevalence of male smokers at the intervention worksite decreasing from 56.2% in 1993 to 47.0% in 2002. In contrast, the smoking prevalence of the control worksites remained largely unchanged, being 60.2% in 1995 and 57.6% in 2002. At the end of the study, the intervention worksite had a significantly lower prevalence of smokers in either the crude or age-adjusted rate. A small-scale but repeated smoking cessation intervention program at a worksite can reduce smoking prevalence more efficiently than the natural trends.