There is an incomplete understanding of the relationship between AD and the risk for COVID-19 infection, according to a study published in JAAD International. “There are inconsistent data in the literature concerning COVID-19 infection rates in patients with AD, with some studies finding an increased incidence of infection and others showing no significant difference,” wrote Jeffrey M. Cohen, MD, and colleagues. To address these inconsistencies, they evaluated the association between AD and COVID-19 infection among adults in the All of Us research program, a National Institutes of Health database with health data from more than 250,000 Americans with a focus on populations that have traditionally been underrepresented in research.

The study team performed a nested, matched, case-control study of the All of Us cohort, which contains participants aged 18 and older from 2018 to present. Aggregate data were collected through a combination of survey responses, physical measurements, EHR data, and genomic information from donation of biospecimens. Participants were asked to complete additional surveys after enrollment, allowing for collection of data on updated medical history, healthcare access and utilization, and more recently, questions concerning COVID-19. In the total cohort of 214,206, the researchers identified 11,752 cases of AD and 47,008 matched controls. Age, sex, and race/ethnicity were well matched between cases and controls.

A 29% Increase in Odds for Having COVID-19

Patients with AD had a 29% increase in odds for having COVID-19 infection, according to Dr. Cohen and colleagues. “Patients with AD were more likely to have a diagnosis of COVID-19 (4.2% vs 2.8%) compared to controls,” they wrote. “Patients with AD were also significantly more likely to have higher mean BMI (30.3 vs 29.9), to have hypertension (59.4% vs 48.9%), hyperlipidemia (63.5% vs 47.3%), type 2 diabetes mellitus (T2DM) (27.7% vs 20.2%), sleep apnea (9.6% vs 6.8%), cardiovascular disease (15.6% vs 10.5%), malignancy (22.0% vs 15.6%), and autoimmune disease (15.0% vs 7.9%).”

AD remained significantly associated with COVID-19 in multivariable analysis (OR, 1.29) after adjusting for demographic factors and comorbidities such as BMI, hypertension, hyperlipidemia, type 2 diabetes (T2D), and auto-immune disease (Table). “In a sensitivity analysis, we calculated E-values to measure potential residual confounding and found that a confounder would need to have an OR of 1.9 to fully explain the association between AD and COVID-19,” the researchers wrote.

AD Comorbidities Are Risk Factors for COVID-19

This large-scale study provides valuable evidence for dermatologists and other clinicians by demonstrating increased incidence of COVID-19 among patients with AD, even after controlling for common comorbidities and known COVID-19 risk factors, such as hypertension and T2D, according to Dr. Cohen and colleagues. “Our findings confirm previously identified associations between AD and various comorbidities,” they noted. “Many AD comorbidities have also been well-documented as significant risk factors for COVID-19 infection, and in particular, risk factors for severe infection with poor outcomes. Although our results were attenuated slightly in multivariable analysis after considering these potential confounding factors, the relationship between AD and COVID remained statistically significant.”

The authors added that study limitations include ascertainment of AD and COVID-19 cases using EHR data and a lack of clinical data, such as AD severity, AD therapy, COVID-19 symptoms, severity, hospitalization, and mortality. Additionally, identification of COVID-19 cases through diagnosis codes may have excluded asymptomatic infections or symptomatic infections that were never confirmed through testing. Also, patients with AD may have more contact with the health-care system, and thus, are more likely to be tested for or diagnosed with COVID-19.

“Further studies are needed to determine the immunopathologic links between AD and COVID-19 infection, and whether certain AD comorbidities or treatments modify the risk of COVID-19 infection,” wrote Dr. Cohen and colleagues.