Blood eosinophils and outcomes in COPD

Abstract

Rationale. In the general population, increased peripheral blood eosinophil (Eos) levels appears to be associated with increased risk of severe exacerbations among COPD patients. Whether the utility of blood eosinophils as a biomarkers at clinical levels is largely unknown. Aim. To evaluate the association between Eos and severe exacerbations and mortality in COPD attending pulmonary clinics. Methods. We recruited from December 1, 2011 to March 30, 2014, smokers (> 20 pack/year) with clinical COPD defined as FEV1/FVC Results. Baseline characteristics were: FEV1 1.67 l (SD 0.64), FEV1 % predicted 62.2% (19.1), age 71 (8.6); 81.5% male. During a follow-up of 3.8 years (median: 0.3-5.1), there was 71 deaths and 373 COPD exacerbation. The mean (± sd) Eos at enrollment was 188 (± 145) cells per µl. At all visits, 91 patients had Eos 400 cells per µl and 87 had variable counts. Using Cox regression models adjusted by age, sex, FEV1% predicted and comorbid conditions, neither baseline Eos nor any Eos cut-of were related to progressive loss of lung function, median annual exacerbation frequency or mortality. Conclusions. Peripheral blood eosinophils levels are not associated with robust outcomes among COPD patients.