Relationship between blood eosinophils, clinical characteristics, and mortality in patients with COPD

Abstract

In patients with COPD, there is controversy regarding the association of blood eosinophil (Eos) levels with 1) exacerbation frequency and 2) the effect of inhaled corticosteroids for prevention of exacerbations. To determine whether Eos define subgroups of patients exhibiting attributes of COPD clinical phenotypes, we compared clinical features and mortality rates in COPD patients from the Initiatives BPCO French cohort categorized using different thresholds of blood Eos levels. 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, body mass index, St George Respiratory Questionnaire (SGRQ) total score, post-bronchodilator spirometry, comorbidities, and medications. Three-year survival between groups was compared using Kaplan–Meier analysis. Three sets of analyses were performed to compare patients with ≥2% versus <2%, ≥3% versus <3%, and ≥4% versus <4% Eos. Eos was available in 458 patients (mean age: 62 years, 72% male, mean forced expiratory volume in 1 second: 51% pred), including 235 patients with Eos ≥2% (49%), 149 with Eos ≥3% (33%), and 90 with Eos ≥4% (20%). For all cutoffs, there was no difference between Eos+ and Eos− groups in univariate analyses except for diabetes and SGRQ score (more frequent and more impaired, respectively, in lower Eos categories). In particular, there was no difference in exacerbation rate, history of asthma, or three-year survival. In conclusion, regardless of the cutoff, Eos+ COPD patients exhibited no specific characteristic in terms of symptoms, lung function, exacerbation rate, and prognosis. These findings suggest that the association of higher Eos with exacerbations reported in previous studies could be population specific, which does not support generalizing the use of Eos as a biomarker for COPD phenotyping.

Prevalence of persistent blood eosinophilia: relation to outcomes in patients with COPD

“…Furthermore, in the CHAIN and BODE cohorts, the prevalence of ICS use was similar in patients with persistently high, intermittently variable or persistently low eosinophil counts (supplementary table S2), thus negating an effect of use of ICSs on the findings reported here. The lack of a relationship between eosinophil level and outcomes is similar to the results reported by ZYSMAN et al [29], who followed 458 patients with COPD for an average of 3 years. They observed no difference in exacerbation rates of asthma or COPD exacerbations irrespective of the threshold of eosinophils used for the analysis.…”

Peripheral eosinophil count as a biomarker for the management of COPD: not there yet

“…More recently, the Copenhagen City Lung study strongly suggested that a high peripheral blood eosinophil count (>340 cells per µL) was associated with an increased risk of severe COPD exacerbations [5]. In contrast, and similar to the results of the ECLIPSE study [6] and of ZYSMAN et al [7], both of which were conducted in patients with COPD, no increased risk of moderate-severe exacerbations was found when a threshold of 2% blood eosinophils was used [5]. Finally, contributing to the overall confusion about the role of eosinophils as a risk factor for COPD outcomes, increased blood eosinophils in patients with COPD were also associated with better lung function, improved quality of life [6,8], and even reduced mortality [9].…”

Blood eosinophil count as a predictor of hospital length of stay in COPD exacerbations

“…6 Another study that had assessed the peripheral eosinophil count of a French cohort (not during exacerbations) found no significant difference in mortality between COPD patients with higher versus lower blood eosinophil levels, for all tested thresholds of eosinophils (2%, 3% and 4%) with a median follow-up period of 48 months. 23 A spot peripheral eosinophil count on hospitalization probably could only have some prognostic use for that particular exacerbation but not on longer term outcome. FEV 1 appeared to have mild improvement for those with higher eosinophil cut-off value.…”