Association between smoking and Behçet's disease: a nationwide population-based study in Korea

Background: There have been conflicting results about the association between Behçet's disease and smoking. Smoking has been reported to be a protective factor for Behçet's disease, whereas smoking may have a role in triggering Behçet's disease. Objectives: The aim of this study was to investigate the incidence of Behçet's disease in Korea according to smoking status using nationwide population data. Methods: We analysed clinical data from individuals 20 years of age and older who received a health examination arranged by the Korean national insurance programme between 2009 and 2012. The incidence of Behçet's disease was analysed according to smoking status reported by individuals during their health examination. Newly diagnosed cases of Behçet's disease were identified using claims data from baseline to the date of diagnosis or until 31 December 2016. Results: The risk of Behçet's disease was lower in current smokers compared with never-smokers regardless of the amount and duration of smoking. The decreased risk of Behçet's disease in current smoker persisted after adjusting for age, sex, regular exercise, drinking status, BMI, diabetes mellitus, hypertension, and dyslipidaemia, history of stroke and/or history of ischaemic heart diseases. Limitations: Genetic susceptibility or family history of Behçet's disease was not considered. Conclusions: This study found a decreased incidence of Behçet's disease in current smokers compared with never-smokers. Further investigation of the pathophysiology responsible for the negative association between smoking and Behçet's disease is needed.