Relationship between blood eosinophil count (Eos), clinical characteristics and mortality of patients with COPD

Abstract

Background: Several studies suggest that, in patients with COPD, Eos is associated with (i) exacerbation frequency and (ii) the effect of inhaled corticosteroid for exacerbation prevention.

Aim: To determine whether Eos defines patients' groups exhibiting attributes of COPD clinical phenotypes, we compared the clinical features and mortality rate between COPD patients with ≥2% (Eos+) and <2% (Eos-) blood eosinophils in the Initiatives BPCO French cohort.

Methods: The following data were collected at inclusion: medical and smoking history, occupational exposures, dyspnea, cough and sputum production, exacerbations in the previous year, history of allergy and asthma, nasal symptoms, BMI, SGRQ score, post-bronchodilator spirometry and plethysmography, comorbidities, CRP and medications. Three-year survival was available for all patients. BOD and ADO scores were calculated.

Results: Eos was available in 458 patients (mean age: 62 years, 72% male, mean FEV1: 51%), including 235 Eos+ patients (49%). No difference between Eos+ and Eos- groups was observed in univariate analyses except for diabetes (17% in Eos-, 8% in Eos+, p=0.02) and SGRQ score (mean, 48 units in Eos -, 40 units in Eos+, p=0.007). In particular, there was no difference in term of exacerbations rate (mean, 1.6/patient/year) or history of asthma (15% of the population). Three-year mortality rate was 17% in Eos- vs 13% in Eos+ (NS).

Conclusion: Apart from differences in health-related quality of life and frequency of diabetes (which warrant further investigation), Eos+ COPD patients exhibit no specific clinical characteristic, especially regarding symptoms, lung function, exacerbations and prognosis.