Potential Markers of COVID-19 Severity Found Among Patients With Chronic Airway Diseases

Eosinopenia and elevated lactate dehydrogenase (LDH) may serve as potential predictors of COVID-19 disease severity among patients with underlying chronic airway diseases, according to results of a retrospective cohort study.

As COVID-19 has spread in the past 2 years, identifying severe cases early on in the disease course has become crucial for administration of effective care and treatment.

“Chronic bronchitis, chronic obstructive pulmonary disease (COPD), and asthma are common respiratory diseases with chronic airway inflammation,” the authors explained. “Eosinophils, neutrophils, and macrophages in innate immune response significantly increase in the airway and lungs during the initial phase of inflammation."

Both lymphocytopenia and decreased circulating eosinophil counts have been reported in patients with COVID-19, leading researchers to hypothesize patients with underlying COPD, asthma, and chronic bronchitis may exhibit different inflammatory states after infection with SARS-CoV- 2—the virus that causes COVID-19—compared with those without chronic airway inflammation.

To test their hypothesis, the investigators analyzed medical records of 59 patients with laboratory-confirmed COVID-19 and underlying chronic airway inflammation who presented to a hospital in China between January and April of 2020.

They compared demographic, clinical, and radiological characteristics and laboratory results of patients with severe and nonsevere disease. Severe COVID-19 was defined as exhibiting “respiratory distress with respiratory frequency ≥30 per minute, pulse oximeter oxygen saturation ≤93% at rest; and oxygenation index (artery partial pressure of oxygen/inspired oxygen fraction) ≤ 300 mm Hg,” the authors wrote.

Of the 1888 patients admitted to the hospital in the study window, 59 had COPD (0.95%), asthma (0.53%) or chronic bronchitis (1.64%). Twenty-six patients were classified as having severe COVID-19, and the median patient age was 71. The majority of patients were male (71%) and had 1 or more comorbidities besides chronic airway disease (53%).

Upon admission, those with severe COVID-19 were more likely to have decreased lymphocyte counts (0.6×10⁹/L vs 1.1×10⁹/L; P < .001), eosinopenia (<0.02×10⁹/L; 73% vs 24%; P < .001), increased LDH (471.0 U/L vs 230.0 U/L; P < .001), and elevated interleukin-6 levels (47.4 pg/mL vs 5.7 pg/mL; P = .002) compared with those with nonsevere COVID-19, the researchers found.

Univariate and multivariate models also revealed eosinopenia and elevated LDH were significantly associated with disease severity, while “eosinophil count and LDH level tended to return to normal range over time in both groups after treatment and severe patients recovered slower than nonsevere patients, especially in eosinophil count,” the authors said. However, no differences were observed in patients with asthma, potentially as a result of the small sample size included.

Previous treatment regimens, including use of inhaled corticosteroids, could contribute to the outcomes of patients with COVID-19, although research on this subject is scarce and more studies are warranted. In addition, different asthma and COPD phenotypes could also play a role in COVID-19 outcomes.

Overall, “our study reveals that eosinopenia and elevated LDH on admission are potential predictors of disease severity in adults with COVID-19 with underlying chronic airway diseases,” the researchers concluded. “Moreover, eosinophil counts could indicate disease progression of COVID-19, thus revealing treatment efficacy. These predictors may help clinicians identify severe COVID-19 in patients with chronic bronchitis, COPD, and asthma.”

Reference:

Chen D, Zhang S, Feng Y, et al. Decreased eosinophil counts and elevated lactate dehydrogenase predict severe COVID-19 in patients with underlying chronic airway diseases. Postgrad Med J. Published online November 22, 2021. doi:10.1136/postgradmedj-2021-139704