Seasonal variation of pediatric asthma exacerbations and its association with asthma phenotypes

BACKGROUND: The objective of this study was to examine the associations of blood inflammatory phenotypes with acute pediatric
asthma exacerbations during different seasons and the COVID-19 pandemic.
METHODS: A retrospective study was conducted involving 32,160 pediatric asthma patients from January 2008 to December 2021.
Asthma blood inflammatory phenotypes were categorized based on low (L) and high (H) eosinophils (E) and neutrophils (N) (LBE/
HBE: ≥ 0.25 × 109/L and LBN/HBN: ≥ 5 × 109/L, respectively) and logistic regression was used to examine the odds ratio (OR) of
outcome variables.
RESULTS: A 109/L increase of neutrophils and eosinophils was associated with a 1.015-fold (95% CI: 1.009–1.021) and a 1.057-fold
increase in the OR (95% CI: 1.026–1.088) for asthma exacerbations of hospitalized pediatric asthma patients. An increase in HBE/LBN
phenotype was associated with a respective 1.232-fold (95% CI: 1.081–1.404) and 1.248-fold (95% CI: 1.101–1.414) increase in the
OR for asthma exacerbations of hospitalized pediatric asthma patients before the COVID-19 pandemic in the winter and autumn
seasons. However, an increase of LBE/LBN phenotype was associated with a respective 0.873-fold (95% CI: 0.769–0.991), 0.872-fold
(95% CI: 0.771–0.986), and 0.813-fold (95% CI: 0.709–0.932) decrease in the OR for asthma exacerbations in the winter, spring and
summer seasons.
CONCLUSIONS: HBE/LBN phenotype had a higher risk of asthma exacerbations among hospitalized pediatric asthma patients in
the winter and autumn, while LBE/LBN phenotype had a lower risk in the winter, spring, and summer.