Aims: To assess the effectiveness of a smoking cessation intervention at the workplace. The intervention was adapted to smokers‘ tobacco dependence, and included minimal structured counselling at the first visit (5–8 minutes), nicotine patches for three months, and three sessions of counselling for reinforcement of abstinence (2–3 minutes) over a three month period.

Methods: Open randomised trial with two groups: the intervention group, and the control group which was subjected to standard clinical practice, consisting of short (30 seconds to one minute) sporadic sessions of unstructured medical antismoking advice. The trial was carried out among 217 smokers of both sexes, aged 20–63 years, motivated to quit smoking and without contraindications for nicotine patches, who were employees at a public transport company and at two worksites of an electric company. The main outcome measure was self reported tobacco abstinence confirmed by carbon monoxide in expired air ≤10 ppm. Analysis was performed according to intention-to-treat.

Results: The rate of continuous abstinence at 12 months was 20.2% for the intervention versus 8.7% for the control group (OR: 2.58; 95% CI: 1.13 to 5.90; p = 0.025). In subgroup analyses, effectiveness of the intervention did not vary substantially with age, tobacco dependence, number of cigarettes smoked per day, number of years of tobacco consumption, degree of desire to quit smoking, time spent with smokers, subjective health, and presence of tobacco related symptoms. Weight gain at 12 months was similar for both groups (1.69 kg in the intervention v 2.01 kg in the control group; p = 0.21).

Conclusions: A simple and easily generalisable intervention at the workplace is effective to achieve long term smoking cessation. In a setting similar to ours, nine subjects would have to be treated for three months for one to achieve continuous abstinence for 12 months.