From the Journals

Eosinophils may predict outcomes in acute COPD exacerbations



High levels of eosinophils had a protective effect for individuals who experienced acute exacerbations of chronic obstructive pulmonary disease, based on data from nearly 1,000 patients.

Several blood biomarkers are under investigation for links to acute exacerbation of chronic obstructive pulmonary disease (AECOPD), which remains one of the top three causes of death worldwide, wrote Riuying Wang, MD, of Third Hospital of Shanxi Medical University, Taiyuan, China, and colleagues.

“Numerous studies have shown the relationship between eosinophilia and clinical outcomes of patients with AECOPD. However, the evidence lacks consensus, and the research thresholds are controversial,” they said.

In a study published in Heart & Lung, the researchers reviewed data from 984 adults with AECOPD over a 3-year follow-up period. The mean age of the patients was 71 years, and 78% were men. The patients’ blood eosinophil levels were grouped into three categories: EOS < 2%, EOS from 2% to < 3%, and 3% or higher. The researchers examined the association between eosinophilia and various comorbidities, treatment, and mortality.

Eosinophilia occurred in 477 cases. The prevalence of eosinophilia in the three groups was 36.48%, 22.87%, and 48.48% respectively, with eosinophilia defined as eosinophil counts of at least 100 cells per microliter, according to the report in Heart & Lung.

An EOS of 2% or higher was associated with significantly fewer cases of complicated pulmonary heart disease and atrial fibrillation than the lower EOS group. Similarly, patients in the EOS group of 2% or higher were less likely to use ventilators and systemic glucocorticoids and those in the EOS less than 2% group had significantly heavier airflow limitation, higher D-dimer, higher burden of infectious inflammation, and higher prevalence of respiratory failure than the other groups.

In addition, significantly fewer deaths occurred during the study period among patients with EOS of 2% or higher, compared with the lower EOS group (P < .01). The findings suggest that “Eosinophils can be used as a prognostic indicator of mortality in AECOPD,” the researchers said.

The researchers also used the area under the curve to examine the predictive value of EOS. The ROC curve showed that the indicators of AUC 0.5 included chest CT imaging, osteoporosis, mental illness, dust exposure, and being a former smoker; however, “the predictive value of EOS by the ROC curve was unstable. Further validation in large samples is needed,” the researchers wrote in their discussion.

The study findings were limited by several factors including the retrospective design and use of data from a single center, the researchers noted. Other limitations included the relatively small sample size and a lack of data on some clinical features and performance metrics, as well as lack of evaluation of chest CT subtypes.

However, the results are consistent with previous studies on infection and antibiotics and reviewed the optimal threshold of AECOPD, the researchers wrote. Based on their findings, “Eosinophils can not only guide clinical treatment but also be used as an index to predict the clinical outcome and prognosis of AECOPD patients,” they concluded.

The study received no outside funding. The researchers had no financial conflicts to disclose.

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