Psoriasis is an inflammatory skin disease associated with increased cardiovascular comorbidity. Smoking is associated with an increased risk of cardiovascular disease, and prior studies have suggested that patients with psoriasis are more likely to be active smokers. Smoking may also be a risk factor in the development of psoriasis. We conducted a systematic review and meta-analysis to assess the prevalence of smoking among patients with psoriasis, and we reviewed the contribution of smoking to the incidence of psoriasis. A total of 25 prevalence and three incidence studies were identified. The meta-analysis of prevalence studies included a total of 146 934 patients with psoriasis and 529 111 patients without psoriasis. Random effects meta-analysis found an association between psoriasis and current smoking [pooled odds ratio (OR) 1·78, 95% confidence interval (CI) 1·52-2·06], as well as between psoriasis and former smoking (pooled OR 1·62, 95% CI 1·33-1·99). Meta-regression analysis did not reveal any sources of study heterogeneity, but a funnel plot suggested possible publication bias. A subset of studies also examined the association between moderate-to-severe psoriasis and smoking, with a pooled OR of 1·72 (95% CI 1·33-2·22) for prevalent smoking. The three incidence studies found an association between smoking and incidence of psoriasis, with a possible dose-effect of smoking intensity and duration on psoriasis incidence. These findings suggest that smoking is an independent risk factor for the development of psoriasis, and that patients with established psoriasis continue to smoke more than patients without psoriasis. What's already known about this topic? Psoriasis is associated with a number of cardiovascular risk factors, many of which are influenced by smoking. What does this study add? Patients with psoriasis are more likely to be current or former smokers. Smoking is also associated with an increased risk of developing psoriasis. These findings emphasize that patients with psoriasis should be screened for smoking, and that public health efforts to reduce smoking could also decrease the incidence of psoriasis.
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