Cigarette smoking and risk of rosacea: a nationwide population-based cohort study

Background: Most evidence regarding the relationship between cigarette smoking and risk of rosacea is obtained from cross-sectional or case–control studies. Objective: To examine the association between smoking and risk of developing rosacea. Methods: Participants were collected from four rounds (2001, 2005, 2009 and 2013) of the Taiwan National Health Interview Survey. Incident cases of rosacea were identified from the National Health Insurance database. Cox proportional hazard model was used for the analyses. Results: Of the 59 973 participants, 379 developed rosacea during a mean follow-up of 10.8 years. After adjustment for potential confounders, current smokers had a lower risk of rosacea than never smokers [adjusted hazard ratio (aHR) 0.60; 95% confidence interval (CI) 0.39–0.92]. An increase in smoking intensity was associated with a decreased risk of rosacea among current smokers (P_trend = 0.0101). Compared with never smokers, current smokers of >15 cigarettes/day had an aHR of 0.51 (95% CI: 0.26–0.99) for rosacea. For incident rosacea, the aHRs (95% CIs) of current smokers of ≤10 years of smoking and ≤10 pack-years of smoking were 0.44 (0.22–0.88) and 0.51 (0.29–0.89), respectively. Former smoking was not associated with rosacea risk. Conclusion: Current smoking was significantly associated with a decreased risk of rosacea.