AAAAI 2021: Asthma Not an Independent Predictor of Severe COVID-19 Outcomes

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Asthma is not an independent risk factor for hospitalization or more severe disease due to coronavirus disease 2019 (COVID-19), according to recent research presented at the 2021 American Academy of Allergy, Asthma and Immunology Virtual Annual Meeting, February 26 – March 1, 2021.

“In our cohort of patients tested for SARS-CoV-2 at Stanford between March and September, asthma was not an independent risk factor in and of itself for hospitalization or more severe disease from COVID,” said lead author Lauren E. Eggert, MD, pulmonologist, clinical assistant professor in the Division of Pulmonary, Allergy, and Critical Care Medicine at Stanford University School of Medicine, in a poster presentation at the meeting. “What’s more, allergic asthma actually decreased the risk of hospitalization by nearly half.”

Eggert also noted that current research regarding the effect of comorbid asthma on the severity of COVID-19 is conflicting.

“The general thought at the beginning of the pandemic was that because COVID-19 is predominantly a viral respiratory illness, and viral illnesses are known to cause asthma exacerbations, that patients with asthma may be at higher risk if they got COVID infection,” said Eggert. “But some of the data also showed that Th2 inflammation downregulates ACE2 receptor, which has been shown to be the port of entry for the SARS-CoV-2 virus, so maybe allergy might have a protective effect.”

To investigate further, Eggert and colleagues examined 5596 patients who tested positive for SARS-CoV-2 at Stanford Health Care between March and September 2020. A total of 605 (10.8%) patients were hospitalized, including 100 (16.5%) patients with asthma. Also, participants’ baseline characteristics were comparable, except hospitalized patients tended to be older.

In a univariate analysis, asthma was significantly associated with COVID-19-related hospitalization (odds ratio [OR], 1.53; 95% confidence interval [CI], 1.2-1.93; P<.001); but, many of the patients had comorbid conditions known to exacerbate COVID-19, including hypertension, diabetes, obesity, and coronary heart disease.

After researchers adjusted for these factors, they found there was not a significant association between asthma and hospitalization due to COVID-19 (OR, 1.12; 95% CI, 0.86-1.45; P<.40). Eggert and colleagues also found that asthma was not significantly associated with disease severity in patients hospitalized with COVID-19 (OR, 1.21; 95% CI, 0.8-1.85; P=.37).

Another interesting finding was that allergic asthma may be protective against COVID-19.

“When we stratified by allergic asthma versus non-allergic asthma, we found that having a diagnosis of allergic asthma actually conferred a protective effect. There was almost half the risk of hospitalization in asthmatics with allergic asthma as compared to others," added Eggert in the presentation.

Eggert also reported that eosinophil levels during hospitalization, even when adjusted for systemic steroid use, correlated with better outcomes, independent of asthmatic status.

Going forward, Eggert said it will be critical for similar studies to be conducted.

"There is also a lot of interest in how this might affect our patients on biologics, which deplete eosinophils and kind of get rid of that allergic phenotype. Does that have any effect on disease severity? Unfortunately, the number of patients on biologics was very small in our cohort, but I do think this is an interesting area for exploration," concluded Eggert.

Reference: Eggert L, Cao S, He Z, et al. Asthma as a predictor of more severe outcomes in COVID-19 infection. Presented at: the American Academy of Allergy, Asthma & Immunology (AAAAI) Virtual Annual Meeting; February 26-March 1, 2021. Abstract 138.