Cigarette Smoking, Alcohol Consumption, and Risk of Alopecia Areata: A Population-Based Cohort Study in Taiwan.

Background: The effects of cigarette smoking and alcohol consumption on the risk of alopecia areata (AA) are unclear. Objective: The aim was to examine the association of cigarette smoking and alcohol consumption with AA. Methods: We collected participants from four rounds (2001, 2005, 2009, and 2013) of the Taiwan National Health Interview Survey. Incident AA cases were identified from the National Health Insurance database. Results: Of the 60,055 participants, 154 developed AA during the 647,902 person-years of follow-up. After controlling for confounders, current smokers had a higher risk of incident AA than never smokers [adjusted hazard ratio (aHR) 1.88; 95% confidence interval (CI) 1.22–2.88]. There was a trend toward an increased risk of AA with increasing numbers of years of smoking and cumulative pack-years of smoking among current smokers. The aHRs (95% CIs) of current smokers of > 5 and ≤ 15 cigarettes per day, > 10 and ≤ 20 years of smoking, ≤ 10, and > 10 and ≤ 20 pack-years of smoking were 2.03 (1.17–3.51), 2.25 (1.21–4.18), 1.86 (1.12–3.09), and 2.04 (1.04–4.01), respectively. Conversely, social and regular drinkers had significantly lower risks of AA than never drinkers [aHRs (95% CIs) 0.65 (0.43–0.98) and 0.49 (0.26–0.93), respectively]. Conclusion: Current smokers had an increased risk of developing AA, while alcohol consumption was associated with a decreased risk of AA. [ABSTRACT FROM AUTHOR]