Major Finding: Data adjusted for age, smoking, body mass index, dietary folate, and physical exercise showed that women who reported drinking more than 2.3 drinks per week had a 1.72 relative risk of developing psoriasis (95% CI, 1.15-2.57), compared with women to did not drink.
Data Source: A study of more than 82,000 women from the Nurses' Health Study II cohort.
Disclosures: Dr. Qureshi disclosed serving as a consultant to pharmaceutical makers Amgen and Genentech; the study was funded by grants from the National Institutes of Health/National Cancer Institute.
Women who drink more than two drinks per week are significantly more likely to develop psoriasis than are women who abstain from alcohol.
Moreover, when stratified by type of alcohol consumed, it is full-calorie, non-light beer—not wine, liquor, or light beer—that appears to raise the risk for the skin condition, according to a study of over 82,000 women published online Aug. 16 in the Archives of Dermatology.
Dr. Abrar A. Qureshi, director of the Translational Research Resource Center in the department of dermatology at Brigham and Women's Hospital, Boston, looked at 116,430 female registered nurses from the Nurses' Health Study II (an ongoing longitudinal study begun in 1989).
The nurses were asked about whether they had ever had a diagnosis of psoriasis between 1991 and 2005, with 1991 being the first year in the study in which alcohol intake data patterns were assessed. Weekly drinking was also assessed in 1995, 1999, and 2003 (doi:10.1001/archdermatol.2010.204).
Overall, among the 47,614 women who responded to the survey and reported consuming alcohol, the mean age was 36 years. It was the same for the 35,058 abstainers who responded.
The only differences between the cohorts were that the abstainers had a slightly higher body mass index (BMI) and were less physically active; drinkers were more likely to smoke or have ever smoked.
Dr. Qureshi and his colleagues found that with adjustment for age only, there was a 1.89 relative risk of developing psoriasis among patients who reported drinking more than 2.3 drinks per week (95% confidence interval, 1.29-2.77).
When adjusted for age, smoking, BMI, dietary folate, and physical exercise, the risk dropped, but only slightly, to 1.72 (95% CI, 1.15-2.57).
Furthermore, when stratified by type of alcohol, having five or more glasses of non-light beer per week was the only beverage to be significantly associated with incident psoriasis, after the multivariate adjustment (RR 1.76; 95% CI 1.15-2.69). Five or more glasses of light beer, white wine, or red wine were not significantly associated with psoriasis, nor were two or more glasses per week of liquor.
Finally, the authors analyzed alcohol intake and confirmed psoriasis according to the Psoriasis Screening Tool questionnaire, a one-page, self-administered, seven-question survey sent to all study participants who reported prior psoriasis diagnosis.
Among this subgroup of confirmed cases, after the same multivariate adjustment used in the earlier analysis, the relative risk associated with any alcohol intake above 2.3 drinks per week was even more pronounced—2.54 (95% CI, 1.57-4.10), and for 5 or more non-light beer drinks per week, it was 2.29 (95% CI, 1.36-3.85).
The authors postulated that beer's gluten content could be the culprit, since gluten has been tied to psoriasis in prior studies.
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