No causal association between atopic dermatitis and COVID-19 outcomes: A Mendelian randomization study

Frequent hand washing and disinfection during the corona virus disease (COVID-19) pandemic may lead to skin-related disability. The causal relationship between atopic dermatitis (AD), the most common chronic, noninfectious, inflammatory skin disease, and COVID-19 remains unclear. We used Mendelian randomization (MR) to explore the causal inference of atopic dermatitis with COVID-19 outcomes.

Genome-wide association study (GWAS) data for AD, consisting of 8383 cases and 236,162 controls of European ethnicity, were provided by the FinnGen database. The GWAS outcome data were derived from the COVID-19 Host Genetics Initiative and consisted of COVID-19 susceptibility (122,616 cases and 2,475,240 controls), hospitalization (32,519 cases and 2,062,805 controls), and very severe respiratory disease (13,769 cases and 1,072,442 controls). The inverse variance weighted with a fixed effects model (IVW (fe)) was used as the main statistical approach to assess the causality between AD and COVID-19 in this study. Several other analytical methods have also been used to complement or identify pleiotropy and heterogeneity.

MR analysis showed no causality between AD and COVID-19 outcomes. The odds ratios (OR) were 1.00 (95% confidence interval (CI), 0.99-1.02) for susceptibility, 1.00 (95% CI, 0.96-1.04) for hospitalization, 0.97 (95% CI, 0.92-1.03) for very severe respiratory disease by the method of IVW (fe).

In conclusion, we found no causal relationship between AD and COVID-19 outcomes. This study provides additional ideas for the exploration of the risk factors for COVID-19.