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Clinical characteristics of eosinophilic asthma exacerbations
Author(s) -
Bjerregaard Asger,
Laing Ingrid A.,
Backer Vibeke,
Fally Markus,
Khoo SiewKim,
Chidlow Glenys,
Sikazwe Chisha,
Smith David W.,
Le Souëf Peter,
Porsbjerg Celeste
Publication year - 2017
Publication title -
respirology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 85
eISSN - 1440-1843
pISSN - 1323-7799
DOI - 10.1111/resp.12905
Subject(s) - medicine , sputum , exacerbation , exhaled nitric oxide , asthma , eosinophilia , spirometry , eosinophilic , gastroenterology , eosinophil , immunology , pathology , tuberculosis
Background and objective Airway eosinophilia is associated with an increased risk of asthma exacerbations; however, the impact on the severity of exacerbations is largely unknown. We describe the sputum inflammatory phenotype during asthma exacerbation and correlate it with severity and treatment response. Methods Patients presenting to hospital with an asthma exacerbation were recruited during a 12‐month period and followed up after 4 weeks. Induced sputum was collected at both visits. Patients underwent spirometry, arterial blood gas analysis, fractional exhaled nitric oxide analysis, white blood cell counts and a screening for common respiratory viruses and bacteria. An eosinophilic exacerbation ( EE ) was defined as having sputum eosinophils ≥ 3% and a non‐eosinophilic exacerbation as < 3% ( NEE ). Results A total of 47 patients were enrolled; 37 (79%) had successful sputum induction at baseline, of whom 43% had sputum eosinophils ≥3% ( EE ). Patients with EE had a significantly lower forced expiratory volume in 1 s ( FEV 1 ) % predicted (70.8%, P = 0.03) than patients with NEE (83.6%). Furthermore, EE patients were more likely to require supplemental oxygen during admission (63% vs 14%, P = 0.002). The prevalence of respiratory viruses was the same in EE and NEE patients (44% vs 52%, P = 0.60), as was bacterial infection (6% vs 14%, P = 0.44). Fractional expiratory nitric oxide ( FeNO ) correlated with sputum %‐eosinophils (ρ = 0.57, P < 0.001), and predicted airway eosinophilia with a sensitivity of 86% and a specificity of 70%. Conclusion Our findings suggest that eosinophilic asthma exacerbations may be clinically more severe than NEEs , supporting the identification of these higher risk patients for specific interventions.