title: Can we predict sputum eosinophilia from clinical assessment in patients referred to an adult asthma clinic?
abstract: BACKGROUND
  There is overwhelming evidence that asthma guidelines aimed at reducing airway inflammation are superior to those based on clinical symptoms alone. This involves targeting eosinophilic inflammation with inhaled corticosteroids.
  
  
  OBJECTIVE
  Because induced sputum is not readily available, our study set out to investigate whether the collective or singular use of routine asthma investigations can predict sputum eosinophilia.
  
  
  METHODS
  Eighty patients underwent skin prick testing, blood tests (IgE, full blood count), spirometry, exhaled fraction nitric oxide (FeNO), PD15 to hypertonic saline, and induced sputum testing at first assessment. A predictive model for sputum eosinophilia (defined as ≥3% eosinophils) was sought using routinely available tests.
  
  
  RESULTS
  Fifty-four subjects underwent both induced sputum and FeNO testing. Seventeen (30%) revealed eosinophilic inflammation, nine (16%) neutrophilic, four (7%) mixed granulocytic and 26 (46%) paucigranulocytic. Positive predictors for sputum eosinophilia included low forced expiratory volume in 1 s (FEV(1))% predicted, raised serum eosinophil, positive smoking history, Polynesian ethnicity and negative asthma family history. There was a non-statistically significant trend for FeNO predicting sputum eosinophilia. The best combination of predictors was low FEV(1)% predicted, raised serum eosinophil, positive smoking history and negative family history of asthma.
  
  
  CONCLUSIONS
  This study demonstrates that the serum eosinophil count and FEV(1) combined with aspects of a clinical history may provide a simple and practical alternative to assessment of airway (sputum) eosinophilia in the clinical setting. A full blood count can be performed at a substantially lesser cost and with greater accessibility than induced sputum. We feel the time has come for the clinical utility of the serum eosinophil count to be revisited.
authors.affiliation: Respiratory Department, Middlemore Hospital, Auckland, New Zealand. eyap@middlemore.co.nz
authors.forename: E
authors.initials: E
authors.lastname: Yap
authors.forename: W M
authors.initials: WM
authors.lastname: Chua
authors.forename: L
authors.initials: L
authors.lastname: Jayaram
authors.forename: I
authors.initials: I
authors.lastname: Zeng
authors.forename: A C
authors.initials: AC
authors.lastname: Vandal
authors.forename: J
authors.initials: J
authors.lastname: Garrett
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D001249:Asthma / Q000150:complications / Q000188:drug therapy / Q000276:immunology / Q000473:pathology*; D001944:Breath Tests; D003430:Cross-Sectional Studies; D004804:Eosinophils; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007073:Immunoglobulin E / Q000032:analysis; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011657:Pulmonary Eosinophilia / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology; D012462:Saline Solution, Hypertonic; D012472:Salivation / Q000187:drug effects; D012882:Skin Tests; D013183:Sputum / Q000166:cytology*
chemical_list: D000305:Adrenal Cortex Hormones; D018927:Anti-Asthmatic Agents; D012462:Saline Solution, Hypertonic; D009569:Nitric Oxide; D007073:Immunoglobulin E