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

Background There have been conflicting results about the association between Behcet's disease and smoking. Smoking has been reported to be a protective factor for Behcet's disease, whereas smoking may have a role in triggering Behcet's disease. Objectives The aim of this study was to investigate the incidence of Behcet'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 Behcet's disease was analysed according to smoking status reported by individuals during their health examination. Newly diagnosed cases of Behcet's disease were identified using claims data from baseline to the date of diagnosis or until 31 December 2016. Results The risk of Behcet's disease was lower in current smokers compared with never-smokers regardless of the amount and duration of smoking. The decreased risk of Behcet'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 Behcet's disease was not considered. Conclusions This study found a decreased incidence of Behcet's disease in current smokers compared with never-smokers. Further investigation of the pathophysiology responsible for the negative association between smoking and Behcet's disease is needed.