Smoking Habit and Psoriasis

Smoking is an independent risk factor for psoriasis, with particularly strong associations for heavy smokers and those who have smoked for many years, according to research published in the March 1 issue of the American Journal of Epidemiology. To determine whether there was an association between psoriasis and smoking, Wenqing Li, Ph.D., of Harvard Medical School in Boston, and colleagues looked at data for 2,410 adults with incident psoriasis who were identified among 185,836 participants from three study cohorts. The researchers found that past and current smokers had an increased relative risk (RR) of incident psoriasis compared with never smokers (1.39 and 1.94, respectively). For current smokers, there was an increasing risk for more cigarettes smoked per day (RRs for one to 14, 15 to 24, and 25 or more cigarettes/day: 1.81, 2.04, and 2.29, respectively). Similarly, there was a trend toward an increased risk of psoriasis with an increasing number of pack-years or duration of smoking, with the highest risk for those with 65 or more pack-years of smoking (RR, 2.72) and for those with a smoking duration of 30 or more years (RR, 1.99). Conversely, the risk of psoriasis was reduced with increasing time since the participant stopped smoking. "Although it has important public health indications, there is [a] lack of awareness of the association between smoking and psoriasis. We provide further evidence showing that smoking is an independent risk factor for the development of psoriasis among U.S. women and men," the authors write.