title: Clinical characteristics of eosinophilic asthma exacerbations.
abstract: 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.
  
  
  
  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).
  
  
  
  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 (FEV1) % 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%.
  
  
  
  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.
authors.affiliation: Respiratory Research Unit, Bispebjerg University Hospital, Copenhagen, Denmark.|Telethon Kids Institute, Perth, Western Australia, Australia.|School of Paediatrics & Child Health, University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Asger
authors.initials: A
authors.lastname: Bjerregaard
authors.affiliation: Telethon Kids Institute, Perth, Western Australia, Australia.|School of Paediatrics & Child Health, University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Ingrid A
authors.initials: IA
authors.lastname: Laing
authors.affiliation: Respiratory Research Unit, Bispebjerg University Hospital, Copenhagen, Denmark.
authors.forename: Vibeke
authors.initials: V
authors.lastname: Backer
authors.affiliation: Respiratory Research Unit, Bispebjerg University Hospital, Copenhagen, Denmark.
authors.forename: Markus
authors.initials: M
authors.lastname: Fally
authors.affiliation: Telethon Kids Institute, Perth, Western Australia, Australia.|School of Paediatrics & Child Health, University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Siew-Kim
authors.initials: SK
authors.lastname: Khoo
authors.affiliation: Department of Microbiology, PathWest Laboratory Medicine Western Australia, Perth, Western Australia, Australia.
authors.forename: Glenys
authors.initials: G
authors.lastname: Chidlow
authors.affiliation: Department of Microbiology, PathWest Laboratory Medicine Western Australia, Perth, Western Australia, Australia.|School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Chisha
authors.initials: C
authors.lastname: Sikazwe
authors.affiliation: Telethon Kids Institute, Perth, Western Australia, Australia.|Department of Microbiology, PathWest Laboratory Medicine Western Australia, Perth, Western Australia, Australia.|School of Pathology and Laboratory Medicine, University of Western Australia, Perth, Western Australia, Australia.
authors.forename: David W
authors.initials: DW
authors.lastname: Smith
authors.affiliation: School of Paediatrics & Child Health, University of Western Australia, Perth, Western Australia, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Le Souëf
authors.affiliation: Respiratory Research Unit, Bispebjerg University Hospital, Copenhagen, Denmark.
authors.forename: Celeste
authors.initials: C
authors.lastname: Porsbjerg
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000150:complications* / Q000503:physiopathology* / Q000628:therapy; D001944:Breath Tests; D018450:Disease Progression; D004802:Eosinophilia / Q000150:complications* / Q000503:physiopathology*; D004804:Eosinophils; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis; D010641:Phenotype; D011237:Predictive Value of Tests; D012137:Respiratory System; D012141:Respiratory Tract Infections / Q000382:microbiology* / Q000821:virology; D013147:Spirometry; D013183:Sputum / Q000166:cytology*; D000067251:Symptom Flare Up; D055815:Young Adult
chemical_list: D009569:Nitric Oxide
keywords: acute asthma; eosinophils; phenotypes; sputum; viral infection