Abstract
BACKGROUND: The association of alcohol with psoriasis has been inconsistent among studies. OBJECTIVES: We aimed (1) to determine whether alcohol consumption (by status, frequency, and subtype of alcohol) modulates smoking-related psoriasis risk in postmenopausal women while stratifying for smoking status and pack-years and (2) to evaluate the effect of smoking cessation on psoriasis risk in postmenopausal women. METHODS: This prospective cohort study included 106,844 postmenopausal women enrolled in the Women's Health Initiative between 1993 and 1998. Patients diagnosed with psoriasis were identified using fee-for-service Medicare International Classification of Diseases, Ninth Revision, Clinical Modification codes assigned by dermatologists or rheumatologists. Self-administered questionnaires were used to obtain information on demographics, medical history, and smoking and alcohol habits. Hazard ratios from Cox regression models were adjusted for ethnicity, income, body mass index, and history of non-melanoma skin cancer and were stratified on age and on randomization status in the Women's Health Initiative study components. RESULTS: In the initial statistical model, past and current alcohol drinkers had higher risks of psoriasis compared with never-drinkers (P-trend < 0.001). This association was not observed after adjusting for cigarette smoking (P-trend: 0.478). The effect of alcohol (by status, frequency, and alcohol subtype) isolated by stratifying the analysis by smoking status (i.e., among never smokers) showed no association with psoriasis. Smoking showed an increasing risk for psoriasis with greater pack-years compared with those who have never smoked (P-trend: < 0.001). Compared to smokers at baseline, past smokers had a lower risk of psoriasis across women who smoked 5-14 cigarettes per day (hazard ratio 0.67, 95% confidence interval 0.51-0.88) and across women who smoked for 5-24 years (hazard ratio 0.65, 95% confidence interval 0.46-0.90). CONCLUSIONS: These findings indicate that alcohol consumption does not modulate smoking-related psoriasis risk. Cigarette smoking, but not alcohol consumption, is an independent risk factor for psoriasis in postmenopausal women. As greater pack-years was associated with a higher risk of psoriasis and smoking cessation was conversely associated with a lower risk of psoriasis for moderate smokers, a greater emphasis on smoking abstinence and cessation counseling may benefit patients who already have other risk factors for psoriasis.