Associations Between Individual Characteristics and Blood Eosinophil Counts in Adults with Asthma or COPD

Elevated blood eosinophil (bEOS) counts are markers of inflammation associated with poorer outcomes in individuals with asthma and chronic obstructive pulmonary disease (COPD). However, little is known about factors impacting the variability of bEOS counts in individuals with these conditions.

To determine the association between individual characteristics and bEOS counts in individuals with asthma, COPD, and nonasthma/COPD controls.

Participants in the National Health and Nutrition Examination Surveys (2001-2016) aged 18 years or older with asthma or COPD and nonasthma/COPD controls were identified on the basis of diagnoses by health care practitioners. Associations between bEOS counts and age, sex, race/ethnicity, body mass index, and smoking status were investigated. Statistical analyses incorporated National Health and Nutrition Examination Surveys multistage sampling and sampling weights.

bEOS counts were significantly higher in individuals with asthma than in nonasthma/COPD controls. There was no significant difference between individuals with COPD and nonasthma/COPD controls. Across all 3 populations, median bEOS counts were consistently higher in men (15%-20%) and in those with higher body mass index (∼5%-25%) and lower in individuals of black race (15%-20%). bEOS counts increased with age in nonasthma/COPD controls but not in individuals with asthma or COPD. Among nonasthma/COPD controls and individuals with asthma, bEOS counts were higher in current and former smokers compared with never smokers, but no such association was found between bEOS counts and smoking status in individuals with COPD.

In individuals with asthma or COPD, sex, race, and body mass index should be considered when interpreting bEOS counts. Smoking history should also be considered in individuals with asthma. Future research should evaluate the association between bEOS counts adjusted for demographic factors and clinical outcomes, such as asthma or COPD exacerbations.