China: Passive Smoking and Eczema Risk

A recent meta-analysis published in the Journal of the European Academy of Dermatology and Venereology has shown an association between passive smoking during pregnancy and an increased risk of eczema development in offspring.

Atopic dermatitis (eczema), a condition that causes dry, itchy, and inflamed skin, is common worldwide. Several studies have explored the modifiable factors of atopic dermatitis (AD), including smoking. The adverse effects of smoking on asthma have been well documented in adolescents; however, the implications of smoking on atopic dermatitis are controversial.

The findings are contradictory and could be due to disparities in study design and covariables adjusted for in the analysis. For instance, the results of a few prospective cohort studies, which reported non-significant or negative correlations between atopic dermatitis and passive smoking, may have exhibited selection bias due to the inclusion of restricted residential regions and a lack of compliance with the survey or involving a small study population. Additionally, because AD generally develops in young individuals and it is rare for children to smoke, the focus of the majority of studies has been the effects of passive smoking on atopic dermatitis in children.

Against the above background, Wenjie Ren, School of Public Health, Xinxiang Medical University, Xinxiang, China, and colleagues examine the evidence of the relationship between active smoking or passive smoking during pregnancy and atopic dermatitis (AD) in offspring.

For this purpose, the protocol was written following the PRISMA Checklist and was registered in the PROSPERO database. The researchers searched online databases to identify all potentially related articles from inception through 1 December 2022. Cohort and case–control studies were assessed using the Newcastle–Ottawa Scale (NOS), and the Joanna Briggs Institute (JBI) critical appraisal tool was used to assess the quality of cross-sectional studies.

Heterogeneity was determined using Cochrane Q tests and I² statistics. Additionally, the reasons for the heterogeneity were analyzed according to the population source, research design, and population size. Fifteen observational studies were included in the analysis.

"Our meta-analysis suggests that atopic dermatitis in offspring is not associated with active smoking during pregnancy (pooled OR, 0.96), however, it is related to passive smoking (OR, 1.52)," the researchers reported.

"Passive smoking during pregnancy is associated with an increased risk of eczema development in offspring."

"More research is required to explore the risk of active smoking and atopic dermatitis development in offspring, particularly the association between measurements of pregnancy cotinine levels in maternal body fluids and AD in offspring," they concluded.

Reference

Chao, L., Liang, W., Zhao, X., Liang, Z., Wu, W., Song, J., & Ren, W. Maternal tobacco exposure during pregnancy and atopic dermatitis in offspring: A systematic review and meta-analysis. Journal of the European Academy of Dermatology and Venereology. https://doi.org/10.1111/jdv.19958