Psoriasis and Smoking: A Systematic Literature Review and Meta-Analysis With Qualitative Analysis of Effect of Smoking on Psoriasis Severity

Background: Smoking has been associated with psoriasis prevalence and severity. Objective: To evaluate prevalence of smoking in patients with psoriasis and to examine the relationship between smoking and psoriasis severity. Methods: MEDLINE, EMBASE, and Cochrane databases (1960-2012) and conference proceedings (2010-2012) were systematically searched using keywords relevant to psoriasis and smoking. Controlled studies addressing psoriasis and smoking status were included. A meta-analysis for the relative risk of smoking in psoriasis patients was performed. Results: Meta-analysis identified a significant association between smoking and psoriasis with a relative risk of 1.88 (95% CI, 1.66-2.13) for smoking in patients with psoriasis versus patients without psoriasis. Eight articles of 11 with data on smoking and psoriasis severity suggested that severity increases with smoking status. Conclusions: This literature review is in favor of a positive association between the prevalence of smoking and psoriasis as well as an association between smoking and severity of psoriasis.