COPD treatment choices based on blood eosinophils: are we there yet?

Abstract

Eosinophils are increasingly being recognised as an important characteristic feature of COPD. Patients with COPD and eosinophilic inflammation tend to respond to steroid therapy; however, many questions remain regarding the optimum measurement. Eosinophilic inflammation may be defined based on various sampling techniques, including eosinophil levels in blood, sputum, bronchoalveolar lavage or biopsy, which leads to inconsistencies in its definition. Blood eosinophils may increase in conjunction with sputum eosinophils during COPD exacerbations and therefore may be a good surrogate marker of airway eosinophilic inflammation. However, the timing of the blood eosinophil measurement, the stability of the eosinophil count and the threshold used in different studies are variable. The use of blood eosinophil count to direct biological therapies in COPD has also had variable outcomes. Eosinophilic inflammation has an important role in COPD management; however, its use as the optimum biomarker still needs further investigation.Key pointsEosinophilia may play a significant role in the pathogenesis of COPD.Eosinophilic inflammation in COPD can be steroid responsive; however, eosinophilic inflammation is variable, and caution needs to be taken with measurements and the thresholds used.The long-term effects of reducing eosinophil levels in COPD is unclear.Educational aimsTo explore current knowledge of eosinophils in COPD.To explore the relationship between eosinophilia and corticosteroid use.To understand the limitations of assessing and using eosinophilia in COPD.

Using biomarkers to adjust corticosteroid dose in patients with severe asthma

“…The choice of optimal T2 biomarkers to use is often debated. Peripheral blood eosinophil count is established as a biomarker of T2 disease in asthma [ 5 ], but also of corticosteroid responsiveness in COPD [ 6 ]. F ENO is also established as a marker of T2 disease [ 7 ], but is less commonly measured than eosinophil counts and requires specific equipment.…”

Blood Eosinophils in Chronic Obstructive Pulmonary Disease: Is There Enough Evidence?

“…According to a US National Science Foundation subcommittee on replicability in science, "Reproducibility is a minimum necessary condition for a finding to be believable and informative". 35 Reproducibility of results (previously described as replicability) refers to obtaining the same results from the conduct of an independent study whose procedures are closely matched; however, this is difficult to obtain when we analyse studies that have explored the role of blood eosinophils in COPD. 36 The possibility of obtaining 'inferential reproducibility', which means drawing the same conclusions from either an independent replication of a study or a reanalysis of the original study, seems more realistic.…”

Eosinophils as a Biomarker in Asthma and COPD

“…We concluded that in asthma patients the eosinophil count is variable than the COPD patients. [8][9][10].…”