Asthma severity tied to more severe COVID-19 outcomes

In a new study, all asthma phenotypes were associated with risk for more severe COVID-19 outcomes, except for type 2 inflammation, researchers reported in the American Journal of Respiratory and Critical Care Medicine.

Researchers conducted a study to analyze the effect of asthma phenotype on COVID-19 outcomes and also to compare rates of COVID-19 hospitalization with influenza and pneumonia. The study included 434,348 adults with asthma (median age, 49.5 years; 58% women) and 748,327 matched individuals (median age, 48.5 years; 57.3% women) in the U.K. who were identified using electronic medical record data. The researchers linked patient-level data to Public Health England SARS-CoV-2 test, hospital and mortality data. Patients with asthma were phenotyped by medication, asthma exacerbation history and type 2 inflammation.

All asthma phenotypes were associated with significantly increased risk for general practitioner-diagnosed COVID-19.

"This could represent a greater risk of infection with SARS-CoV-2 for asthma, but there was also a significant association with GP consultation for advice on COVID-19 and reporting exposure to COVID-19. In addition, patients with asthma were significantly less likely to have their suspected COVID-19 diagnosis confirmed, indicating a higher risk of false-positive labeling of COVID-19 in asthma than the general population. Put together, these findings suggest that patients with asthma had increased healthcare-seeking behavior and GPS a lower threshold to diagnose COVID-19 in them,” Chloe I. Bloom, MD, senior clinical research fellow in the Airways Disease Section at the National Heart and Lung Institute at Imperial College London, and colleagues wrote.

Risk for COVID-19 hospitalization was significantly associated with the following:

• asthma with inhaled corticosteroid (ICS) use (adjusted HR = 1.27; 95% CI, 1.01-1.61);
• intermittent ICS plus add-on asthma medication use (aHR = 2; 95% CI, 1.43-2.79);
• regular ICS plus add-on asthma medication use (aHR = 1.63; 95% CI, 1.37-1.94); and
• asthma with frequent exacerbations (aHR = 1.82; 95% CI, 1.34-2.47).

These phenotypes were also significantly associated with hospitalizations for influenza and pneumonia, according to the researchers.

“Although the incident rate of hospitalization was considerably higher for COVID-19 than either pneumonia or influenza in the overall population, the elevated adjusted association between asthma and risk of hospitalization was similar between the three respiratory infections. This finding even held true for those younger patients, aged < 55 years,” Bloom and colleagues wrote.

The researchers reported significantly higher risks for ICU admission and mortality among patients with asthma and regular ICS plus add-on therapy (aHR = 1.7; 95% CI, 1.27-2.26) and those with frequent exacerbations (aHR = 1.66; 95% CI, 1.03-2.68).

“Our findings suggest that COVID-19 outcomes are related to asthma severity, as defined by use of maintenance inhaler medication and exacerbation history,” Bloom and colleagues wrote.

Atopy and blood eosinophil counts were not associated with more severe COVID-19 outcomes. The researchers wrote that they “found no association between severe COVID-19 outcomes and probable type 2 inflammation.”

The researchers noted several limitations of the current trial, including data from only the first wave of COVID-19 in the U.K. and before the availability of COVID-19 vaccines.