Objective: To analyze the association of psoriasis with smoking habits and alcohol consumption before first diagnosis by a dermatologist.
Design: A multicenter case-control study. Interviews were conducted by trained medical investigators using a structured questionnaire.
Setting: Outpatient services of 10 general and 10 teaching hospitals in northern and southern Italy.
Subjects: Patients with a first diagnosis of psoriasis made by a dermatologist and a history of skin manifestations of no longer than 2 years after the reported disease onset. Patients with new diagnoses of skin diseases other than psoriasis were selected as control subjects. A total of 404 case patients (median age, 35 years) and 616 controls (median age, 36 years) were included in the analysis.
Results: The risk for psoriasis was higher in ex-smokers and in current smokers than in patients who never smoked. The relation with smoking was stronger and more consistent among women than men. In men, a significant association was restricted to the ex-smoker status. Smoking was strongly associated with pustular lesions (29 patients) with an adjusted odds ratio of 10.5 (95% confidence interval, 3.3-33.5) for those smoking more than 15 cigarettes per day. No significant overall association with alcohol consumption was documented after controlling for smoking habits. However, the risk seemed to vary according to sex, with a moderate association being documented in men.
Conclusions: Cigarette smoking and, in men, alcohol consumption are associated with psoriasis. There is a strong association between smoking and pustular lesions.