Current smokers may be less likely to develop rosacea, suggest results from a prospective cohort study published in the Journal of the European Academy of Dermatology & Venereology. These data challenge previous studies that demonstrated a positive association between smoking and certain inflammatory diseases, including rosacea.
Investigators abstracted data from the National Health Interview Survey (NHIS) in Taiwan. The NHIS is administered every 4 years to a nationally representative sample of Taiwanese residents to assess population health status, health behaviors, and healthcare utilization. Participants aged ≥12 years who participated in the NHIS during the years 2001, 2005, 2009, and 2013 were recruited for the present study. NHIS data were linked to the National Health Insurance Research Database (NHIRD), which provides comprehensive demographic information and healthcare claims data. Patients were followed from time of NHIS participation until diagnosis of rosacea, death, or study conclusion in December 2017. Diagnosis of rosacea was ascertained from NHIRD records; patients with at least 1 inpatient or 3 outpatient visits with a rosacea code were considered to have incident rosacea. Patients were classified as ever, current, or never smokers in analyses. Current smokers were further delineated into categories based on smoking intensity. Cox proportional hazard models were used to assess the risk for incident rosacea by smoking status. Models were adjusted for age, sex, marital status, education level, household income, comorbid conditions, body mass index (BMI), and alcohol consumption.
A total of 59,973 individuals were included in the study, of whom 50.3% were men. Mean age at NHIS administration was 40.6 ± 17.8 years; mean follow-up time was 10.8 ± 4.5 years. Overall, 73.7% of participants (n=44,188) were never smokers, 21.6% (n=12,979) were current smokers, and 4.7% (n=2806) were former smokers. Over 645,932 person-years of follow-up, 379 participants developed rosacea. The incidence rates for rosacea in never, current, and former smokers were 71.86, 21.64, and 19.71 cases per 100,000 person-years, respectively. In the fully adjusted model, current smokers had a lower risk for incident rosacea compared with never smokers (adjusted hazard ratio [aHR], 0.60; 95% confidence interval [CI], 0.39-0.92). Men and participants with rural residence were also less likely to develop rosacea. By contrast, hyperlipidemia, chronic liver disease, and connective tissue disease were associated with increased risk for rosacea. In adjusted models, increased smoking intensity appeared to predict lower incidence of rosacea (P =.0101). Specifically, patients smoking >15 cigarettes per day had an adjusted HR of 0.51 (95% CI, 0.29-0.99) for incident rosacea compared with never smokers. Among patients smoking <15 cigarettes per day, however, risk for rosacea was comparable to that of never smokers. When stratified by smoking duration, current smokers with ≤10 and >10 pack-years of smoking had adjusted HRs of 0.44 (95% CI, 0.22-0.88) and 0.51 (0.29-0.89), respectively.
As study limitations, investigators noted the risk for misclassification bias and the lack of data on rosacea subtypes.
These results suggest that current smokers may be at lower risk for incident rosacea than never smokers. Results remained robust in sensitivity analyses for potentially misdiagnosed conditions. The mechanisms which underlie this relationship between rosacea and smoking remain unclear, although smoking-associated vasoconstriction of peripheral arteries may be a factor.
Dai YX, Yeh FY, Chou YJ, et al. Cigarette smoking and risk of rosacea: a nationwide population-based cohort study [published online May 13, 2020]. J Eur Acad Dermatol Venereol. doi: 10.1111/jdv.16595