Across the board, researchers saw that studies of active smokers showed increased prevalence of the skin condition, regardless of age or region. It isn't quite clear, though, whether smoking causes AD or AD causes people to smoke.
A recent and expansive review of previous studies found some evidence correlating smoking rates with increased risk of atopic dermatitis (AD). The researchers examined 86 studies to determine the association between an AD diagnosis and smoking, passive exposure to smoke, and smoking during pregnancy.
Thousands of papers turned up in the initial literature search and the pool was whittled down based on relevance and quality. Twenty of the studies yielded data on “active smoking”, 66 contained data on secondhand smoke, and 23 had mention of maternal smoking. The authors of the meta-analysis made note both of each study’s relative quality and how each diagnosed AD.
Across the board, they found that studies of active smokers showed increased prevalence of AD, regardless of age or region. Though two studies examined amount of smoking in conjunction to AD (“AD was significantly associated with both mild (OR 2.68, 95% CI 1.78-4.04) and extensive (OR 2.70, 95% CI 1.11-6.60) amounts of active smoking with similar effect sizes”), none measured AD severity in active smokers.
Results from the studies on passive exposure to tobacco smoke were mixed, with significant correlations found in research that originated in South America and Africa and marginal correlations in Asia, but no link of statistical significance in studies from North America or Europe. In the studies that did seem to indicate some link, older patients exposed to smoke were at a higher risk.
Perhaps surprisingly, no significant link was found between AD risk and maternal smoke, particularly in the largest, highest-quality studies the authors reviewed, despite the countless harmful outcomes associated with smoking during pregnancy.
The authors write that “the results of this meta-analysis of observational studies suggest that active smoking and passive exposure to cigarette smoke in the home are associated with higher prevalence of AD in both children and adults.” While that may be evident, they do note that all of the studies of active smokers were cross-sectional, meaning they could not determine “whether smoking causes AD or vice versa.”
The analysis was published in The Journal of the American Academy of Dermatology.