Blood eosinophil counts in the general population and airways disease: a comprehensive review and meta-analysis

Abstract

BackgroundThe clinical context for using blood eosinophil (EOS) counts as treatment-response biomarkers in asthma and chronic obstructive pulmonary disease (COPD) requires better understanding of EOS distributions and ranges. We describe EOS distributions and ranges published in asthma, COPD, control (non-asthma/COPD) and general populations.MethodsWe conducted a comprehensive literature review and meta-analysis of observational studies (Jan 2008 to Nov 2018) that included EOS counts in asthma, severe asthma, COPD, control and general populations. Excluded studies had total sample sizes <200, EOS as inclusion criterion, hospitalised population only, exclusively paediatric participants.ResultsOverall, 91 eligible studies were identified, most had total-population-level data available: asthma (n=39 studies), severe asthma (n=12 studies), COPD (n=23 studies), control (n=7 studies), general populations (n=14 studies); some articles reported data for multiple populations. Reported EOS distributions were right-skewed (n=7 studies). Reported median EOS counts ranged from: asthma, 157–280 cells·µL−1 (n=22 studies); severe asthma, 200–400 cells·µL−1 (n=8 studies); COPD, 150–183 cells·µL−1 (n=6 studies); controls, 100–160 cells·µL−1 (n=3 studies); general populations, 100–200 cells·µL−1 (n=6 studies). The meta-analysis showed observed variability was mostly between studies rather than within studies. Factors reportedly associated with higher blood EOS counts included: current smoking, positive skin prick test, elevated total IgE, comorbid allergic rhinitis, age ≤18 years, male sex, spirometric asthma/COPD diagnosis, metabolic syndrome and adiposity.ConclusionEOS distribution and range varied by study population, and were affected by clinical factors including age, smoking history and comorbidities which, regardless of severity, should be considered during treatment decision making.

Impact of Blood Eosinophil Variability in Asthma: A Real-Life Population Study

“…Regarding the interindividual variability of normal values of blood eosinophils according to clinical characteristics, a recent study performed in a general population found higher eosinophil count in males, higher levels in individuals with T2 characteristics and no changed was found with age (17) . A recent meta-analysis in general population and patients with airway diseases found that eosinophil distribution and range varied by study population, and were affected by clinical factors including age, smoking history and comorbidities which, regardless of severity (18). All these findings are in line with ours.…”

Inverse association between Helicobacter pylori infection and childhood asthma in a physical examination population: a cross-sectional study in Chongqing, China

“…It is well known that family history of allergies and blood eosinophil counts are strongly associated with childhood asthma [29,30]. Recently, the association between BMI and childhood asthma has received increasing attention.…”

Tumefactive eosinophil‐rich non‐granulomatous small vessel vasculitis in the cerebrum in a patient with idiopathic hypereosinophilic syndrome

“…Several factors, including elevated IgE and allergic rhinitis, are associated with higher blood eosinophil counts. 9 However, the total number of peripheral blood eosinophils does not exceed 1.5 Â 10 9 /L in patients with asthma, regardless of the clinical severity, 10 even with comorbid allergic rhinitis. 11 Based on these previous observations, allergic rhinitis and parasinusitis may not necessarily be considered direct causes of blood hypereosinophilia in the present case.…”

“…HE in the present case appears to be secondary (reactive) to allergic rhinitis and parasinusitis as possible underlying conditions. Several factors, including elevated IgE and allergic rhinitis, are associated with higher blood eosinophil counts 9 . However, the total number of peripheral blood eosinophils does not exceed 1.5 × 10 9 /L in patients with asthma, regardless of the clinical severity, 10 even with comorbid allergic rhinitis 11 .…”