Alcohol intake: a risk factor for psoriasis in young and middle aged men?

OBJECTIVE--To clarify the nature of the association between alcohol intake and psoriasis. DESIGN--Case-control study of men aged 19-50 with onset of skin disease in 1976 or later. SETTING--Outpatient clinics of the departments of dermatology of the university central hospitals in Helsinki, Oulu, and Tampere from September 1987 to April 1989. SUBJECTS--144 Patients with psoriasis and 285 unmatched controls with other skin diseases. MAIN OUTCOME MEASURES--Results of clinical examination and self administered questionnaire assessing lifestyle and alcohol intake during two specified periods--namely, 12 months before the onset of skin disease and 12 months before the date of examination. RESULTS--Recalled mean alcohol intake before the onset of skin diseases was 42.9 g/day among the patients with psoriasis and 21.0 g/day among the controls. In logistic regression analysis psoriasis was associated with alcohol intake but not with coffee consumption, smoking, age, marital state, or social group. The odds ratio for psoriasis at an alcohol intake of 100 g/day compared with no intake was 2.2 (95% confidence interval 1.3 to 3.9). The controls decreased their alcohol intake after the onset of the disease but the group with psoriasis did not. Analysis of serum enzyme values showed that gamma-glutamyltransferase activity was significantly correlated with alcohol intake (r = 0.35), the mean activity being 75.0 U/l among patients with psoriasis and 41.9 U/l among controls. CONCLUSIONS--Alcohol is a risk factor for psoriasis in young and middle aged men, and psoriasis may sustain drinking.