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.