Factors associated with cessation of smoking among Swiss adults between 1991 and 2011: results from the SAPALDIA cohort.

INTRODUCTION: Smoking is still the most preventable cause of disease and premature death in Switzerland, as elsewhere. We aimed to assess the main determinants of smoking cessation in the population-based cohort of SAPALDIA (Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults). METHODS: The SAPALDIA study was initiated in 1991 with 9651 participants aged 18 to 60 years from eight areas (S1). Follow-up assessments were conducted in 2002 (S2; 8047 participants) and 2010/11 (S3; 6088 participants). At each survey, detailed information on health and potential health-related factors was collected and lung function measured. Using logistic regression, we assessed predictors of smoking cessation between S1 and S2 and between S2 and S3. RESULTS: In both periods, highest educational level (summary odds ratio [OR] 1.49, 95% confidence interval [CI] 1.08-2.06; ref. lowest level), FEV1/FVC < 0.5 (OR 6.19, 95% CI 2.44-15.7, ref. FEV1/FVC >= 0.7), higher age in men (OR 1.02, 95% CI 1.01-1.03, per year) and overweight (OR 1.38, 95% CI 1.16-1.64) were significant predictors of smoking cessation. Nicotine dependence (OR 0.97, 95% CI 0.96-0.98, per cigarette smoked a day) and female sex between age 45 and 60 (e.g., OR 0.74, 95% CI 0.61-0.91, at age 50) were negatively associated with smoking cessation. Moreover, smokers at S2 reporting a diagnosis of depression were less likely to quit smoking by S3 (OR 0.53, 95% CI 0.30-0.93). CONCLUSIONS: Prospective tobacco control policies in Switzerland should be addressed to women, younger persons and persons of lower education.