Colby Stong
Atopic diseases are not associated with blood eosinophil count early in childhood, although a strong association was observed at 6 years of age, according to study findings published in Pediatric Allergy and Immunology.
Researchers in Copenhagen evaluated the association between blood eosinophil count (BEC) in children and the development of atopic diseases among children up to 6 years of age, using data from the ongoing COPSAC2000 and COPSAC2010 mother-child cohorts.
COPSAC2000 included 411 children of mothers with a history of asthma who were enrolled during the first month of life from 1998 to 2001. COPSAC2010 included 700 children of pregnant mothers enrolled at week 24 of pregnancy from 2008 to 2010. The families attended a research clinic for regular sessions and for acute symptoms from birth until age 6 years.
Overall, 956 (86.1%) of the 1111 children had at least 1 blood eosinophil count at age 18 months (n= 687) or 6 years (n=769) and were included in the analyses.
No association between blood eosinophil count and recurrent wheeze/asthma, atopic dermatitis, or allergic sensitization to inhalant allergens was found at age 18 months, although a significant association with sensitization to food allergens or any allergen was observed. At age 6 years, a significant association occurred between blood eosinophil count and recurrent wheeze/asthma (odds ratio [OR], 1.10; 95% CI, 1.04-1.16; P =.0005), atopic dermatitis (OR, 1.06; 95% CI, 1.01-1.12; P =.02), and allergic rhinitis (OR, 1.11; 95% CI, 1.05-1.18; P =.0002).
For children who had recurrent wheeze/asthma or atopic dermatitis at age 18 months, blood eosinophil count was not associated with disease persistence until age 6 (recurrent wheeze/asthma: hazard ratio [HR] of time to remission, 1.0; 95% CI, 0.85-1.18; P =.96; atopic dermatitis: HR of time to remission, 0.95; 95% CI, 0.83-1.08; P =.42).
Overall, blood eosinophil count at age 18 months was not associated with later recurrent wheeze/asthma, allergic rhinitis, atopic dermatitis, or allergic sensitization at 6 years. A trend was observed in which children with current atopic dermatitis by age 6 years had increased blood eosinophils at 18 months (geometric mean ratios [GMR], 1.18; 95% CI, 1.00-1.40; P =.05) as well as increased eosinophil counts at 6 years of age (GMR, 1.30; 95% CI, 1.10-1.54; P =.002). No atopic dermatitis temporal trajectories were associated with blood eosinophil count at 18 months, and all the trajectories had a significantly increased eosinophil count at 6 years vs healthy children (transient atopic dermatitis: GMR, 1.21; 95% CI, 1.05-1.38; P =.008; late-onset atopic dermatitis: GMR, 1.31; 95% CI, 1.03-1.67; P =.03; and persistent atopic dermatitis: GMR, 1.40; 95% CI, 1.13-1.74; P =.002).
Blood eosinophil count at 18 months had a strong association with an elevated blood eosinophil count at 6 years of age (beta-coefficient = 0.28; 95% CI, 0.19-0.37; P <.0001).
A study limitation is the inclusion of few children with severe atopic disease. Also, the timing of blood sampling may not have been ideal for disease prediction, and eosinophil activation was not evaluated.
“In opposition to current management guidelines, this study questions the clinical value of blood eosinophil count measured in toddlers as a predictive biomarker for subsequent atopic disease in early childhood,” the study authors stated.
References:
Jensen SK, Melgaard ME, Pedersen C-ET, et al. Limited clinical role of blood eosinophil levels in early life atopic disease: a mother–child cohort study. Pediatr Allergy Immunol. 2023;34(11):e14050. doi:10.1111/pai.14050