Testing blood eosinophils at admission could have ‘significant prognostic implications’, say researchers.
Elderly COPD patients with a blood eosinophil count of 150 cells/μL or more on admission to hospital for covid are significantly more likely to develop respiratory and systemic complications than those without COPD.
However, the study of almost 2000 elderly patients hospitalised for covid in Hong Kong found that there was no increased risk in these COPD patients if the blood eosinophil counts were under that threshold.
Patients with high eosinophil counts were more likely to need invasive mechanical ventilation, ICU, systemic corticosteroid treatment and to develop a secondary bacterial infection.
“This group of patients also have the longest length of stay upon admission for covid-19. The findings of this study not only concur with previous reports that COPD being a risk factor of severe covid-19 but also identify a subgroup with admission blood eosinophil count ≥ 150 cells/μL who have the worse prognosis with more severe covid-19,” the authors wrote.
They said the findings provided a “readily available tool” that clinicians could use to strategy the risks in these patients.
“Elderly and COPD have been considered to be one of the independent prognostic factors in covid-19. But from our study findings, the phenotype of COPD also plays an important role in prognostication.”
The researchers analysed hospital data from patients over age 65 without a history of asthma, 133 of whom had COPD. They found 93 with blood eosinophil counts on admission less than 150 cells/μL and 40 had blood eosinophil counts of 150 cells/μL or more.
Patients with a high eosinophil count had five times the odds of respiratory failure, more than twice the odds of invasive mechanical ventilation and more than twice the odds of ICU admission than those without COPD. Patients with a lower eosinophil count had no greater odds of covid severity.
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The researchers said that doctors should consider more aggressive treatment in these patients earlier in the disease to prevent complications.
“Early aggressive treatment for these patients may not only be able to prevent major complications from covid-19 and shorten their hospital length of stay, but it may also have long term benefits for these patients.
“By preventing developing respiratory complications, this may help to prevent any potential lung damage including post-inflammatory fibrosis in these patients, who already have compromised lung function due to underlying COPD.”
More investigation was needed to understand whether inhaled corticosteroids could help these patients, they added.
“Although inhaled corticosteroid should only be prescribed for patients with COPD with history of exacerbation and of eosinophilic phenotype, the finding of our study, as well as that has been reported in this literature, may suggest for further research direction on this area.”
