Prognostic Factors in Severe Eosinophilic Asthma in a Pediatric Population: A Prospective Cohort Study in Spain

Background/Objectives: The objective of this study was to provide real-world data on prognostic factors in children with severe eosinophilic asthma and to assess biomarkers of outcome. Methods: Fifty-nine children (aged 6-17 years) were included in a prospective cohort attended in a Severe Asthma Unit of a tertiary care teaching hospital in Badalona (Barcelona, Spain) and visited at baseline and at 1-year follow-up. Study variables included asthma control using the Asthma Control Test (ACT), forced expiratory volume in one second (FEV1), exacerbation episodes, fractional exhaled nitric oxide (FeNO), and inflammatory biomarkers (blood tests, sputum cells, immunoallergic tests, and levels of cytokines and effector cells in blood and sputum). Results: There were 36 boys and 23 girls, with a mean (SD) age of 11.9 (2.8) years. Uncontrolled severe asthma was diagnosed in 83.1% of cases, with poor symptom control (ACT score < 20) in 52.5%, obstructive pattern (FEV1 < 80% predicted) in 35.6%, and more than one exacerbation in the previous year in 30.5%. The mean duration of asthma was 9.2 (3.6) years. Positive prick tests were recorded in 55 patients, with polysensitization in 6. The mean percentage of sputum eosinophils was 2.5% (3.1%), and the mean eosinophil blood count 543.4 (427.7) cells/µL. Ten patients (32%) showed sputum eosinophilia (>3% eosinophils). Sputum eosinophils did not correlate with blood eosinophils, FeNO, and serum periostin. At 12 months, 13 (22%) children had uncontrolled asthma and 46 (78%) had controlled asthma. Variables significantly associated with uncontrolled asthma were duration of asthma (OR = 1.23, 95% CI 1.01-1.49, p = 0.04) and an ACT score < 20 (OR = 0.80, 95% CI 0.69-0.93, p = 0.004). Lower serum levels of IL-9 appeared to be related with uncontrolled asthma, but statistical significance was not reached. Conclusions: Pediatric severe eosinophilic asthma showed a predominant allergic phenotype with symptomatic disease as a main contributor of uncontrolled asthma at 1 year. Predictive biomarkers of outcome were not identified. Further studies are needed to confirm the present findings especially considering additional variables for a better phenotypic characterization of severe eosinophilic asthma in children and to study in-depth the role of inflammatory biomarkers.