Association of atopic dermatitis with smoking: A systematic review and meta-analysis

Background: Tobacco exposure might be a modifiable risk factor for atopic dermatitis (AD). Objective: We examine the association between AD and exposure to tobacco smoke. Methods: We performed a systematic review and meta-analysis of observational studies (n = 86) in MEDLINE, EMBASE, Scopus, and Cochrane Library (1823-2015). Quality of evidence was assessed using the Newcastle-Ottawa Scale (NOS). A meta-analysis was performed using random-effects models to estimate pooled odds ratios (OR). Subset analyses were performed for different ages (children, adult), regions, study designs (cross-sectional, longitudinal), study sizes (<5000, 5000), study quality (NOS score <6, and amount of smoking (mild, extensive). Results: A diagnosis of AD was associated with higher odds of active smoking (OR 1.87, 95% confidence interval 1.32-2.63) and exposure to passive smoke (OR 1.18, 95% confidence interval 1.01-1.38), but not maternal smoking during pregnancy (OR 1.06, 95% confidence interval 0.80-1.40). The association between active smoking and AD remained significant in children and adults, all continents studied, and study sizes, but all were cross-sectional designs and had NOS score 6 or greater. Passive smoke was associated with AD in children and adults, cross-sectional studies, South/Central American and African studies, study size less than 5000, and NOS score less than 6. Limitations: AD severity and distribution were not assessed. Conclusions: Active and passive exposure to smoke are associated with increased AD prevalence.