Blood eosinophil counts and exacerbation risk in stable COPD with ≤1 moderate exacerbation on dual bronchodilator...

High blood eosinophil counts correlate with the risk of future exacerbations. It is uncertain whether this correlation is still valid even in stable chronic obstructive pulmonary disease (COPD) patients receiving optimal management.

To evaluate whether increased blood eosinophil counts are associated with future exacerbation risk in stable COPD patients receiving dual bronchodilator use.

This study used data from the Korean COPD Subgroup Study (KOCOSS) cohort. Stable COPD was defined as experiencing fewer than two moderate or no severe exacerbations in the previous year. The exposure variable was blood eosinophil level, with a high level defined as ≥ 300 cells/μL. The primary and secondary outcomes were the moderate-to-severe and severe acute exacerbation of COPD (AECOPD). The risk of AECOPD was assessed using a multivariable Cox regression model.

Over a median follow-up of 12 months (interquartile ranges, 6-24 months), the incidence of moderate-to-severe AECOPD was 16.5 %. In multivariable analysis, the risk of moderate-to-severe and severe AECOPD increased by 14 % and 27 % for every 100-cell/μL increase in blood eosinophil count (95 % CI: 1.00-1.30). Patients with a high eosinophil count also exhibited an increased risk of moderate-to-severe AECOPD compared to those without (adjusted hazard ratio [aHR] = 1.79, 95 % confidence interval [CI] = 1.05-3.03). Exploratory analyses showed that higher blood eosinophil counts were also associated with an increased the risk of severe AECOPD (aHR: 1.27, 95 % CI: 1.04-1.54).

Higher blood eosinophil counts were associated with an increased risk of AECOPD in stable COPD patients, even among those receiving dual bronchodilators.