Population-based evaluation of blood eosinophil counts and association with patient characteristics in US adults with asthma
Sunday, March 4, 2018
South Hall A2 (Convention Center)
Herve Caspard, MD, ScD, Trung N. Tran, MD PhD, Chris Ambrose, MD
RATIONALE: Blood eosinophil count (EOS) is a marker of asthma exacerbation risk, and evidence suggests that reducing EOS leads to improved outcomes in severe asthma.

METHODS: National Health and Nutrition Examination Survey (NHANES) participants aged 18 to 64 years from 2001 through 2014 with documented EOS were analyzed. Individuals with asthma were identified based on patient report of current asthma. Allergic asthma was defined as total IgE ≥30 IU/mL, with allergen-specific IgE ≥0.35 IU/mL to at least one perennial allergen. Statistical analyses incorporated NHANES multistage sampling and sampling weights.

RESULTS: Of 28,377 participants with EOS, 2,223 were identified with asthma. EOS were greater for asthmatics than non-asthmatics (medians: 198 [95% CI: 189‒207] vs. 156 [153‒159] cells/µl, p<0.001). For asthmatics, EOS were greater in men than women (228 [212;243] vs. 184 [174‒195], p<0.001), in Hispanics and whites vs. blacks (200 [190;209] and 218 [205;231] vs. 173 [159‒187], p<0.001), with BMI <30 vs. ≥30 kg/m2 (208 [199‒217] vs. 167 [151‒184], p=0.01), with ever- vs. never-smokers (211 [195‒226] vs. 187 [176‒198], p=0.02), with allergic vs. non-allergic asthma (251 [202‒299] vs. 175 [145‒206], p<0.01), and fractional exhaled nitric oxide >50 vs. ≤50 ppb (399 [332‒467] vs. 186 [172‒199], p<0.001). There was no difference by age (p=0.15) or age at onset (p=0.38). After multivariate analyses, associations between EOS and sex, race/ethnicity, BMI, and smoking history remained.

CONCLUSIONS: Sex, race/ethnicity, BMI, and smoking history should be considered when interpreting EOS in asthmatic patients. As expected, elevated EOS correlated with other markers of T2 inflammation.