Identifying clinical and demographic characteristic differences between eosinophilic and non-eosinophilic asthma and detecting predictors of eosinophilic asthma among Egyptian asthmatic patients

Abstract
Introduction
Asthma is a heterogenous disease with various phenotypes that is characterized by airway limitation due to bronchospasm and airway inflammation associated with excessive mucus secretion. Eosinophilic asthma subtype is described as a late onset asthma that presents with more severe respiratory symptoms, and with sputum eosinophilia ≥ 3%. In the current study, we aimed to identify the difference in the clinical and demographic characteristics between eosinophilic and non-eosinophilic asthma subtypes and to determine predictors of eosinophilic asthma.

Materials and methods
One hundred bronchial asthma patients with age ≥ 18 years were divided into two groups according to sputum eosinophilia. All patients were subjected to medical history, Asthma Control Test (ACT), spirometry, serum IgE level, skin prick testing (SPT), and nasal endoscopy to detect nasal polyposis and allergic signs.

Results
No statistical difference was found between eosinophilic and non-eosinophilic asthma patients regarding age, gender, and body mass index. Patients with sputum eosinophilia had more severe obstruction by spirometry, and positive SPT to food allergens, pollens, and latex with statistical significance (p values 0.001, 0.016, and 0.017 respectively). Additionally, patients with sputum eosinophilia had lower ACT score, higher serum IgE level and higher serum eosinophil count. Total IgE had the highest diagnostic accuracy for discrimination of sputum eosinophilia among asthma patients. Pollen allergy and the severity of airway obstruction by spirometry were independent predictors of eosinophilic asthma.

Conclusion
Patients with eosinophilic asthma had more severe airway obstruction, lower ACT scores, higher serum IgE level, and serum eosinophil count. Pollen allergy and obstructive pattern by spirometry were independent predictors of eosinophilic asthma.