title: Diagnostic Accuracy of Inflammatory Markers for Diagnosing Occupational Asthma.
abstract: BACKGROUND
  The assessment of airway responsiveness and inflammation is key to the investigation of occupational asthma (OA).
  
  
  OBJECTIVE
  We sought to assess and compare the diagnostic accuracies of the blood and sputum eosinophil counts and the methacholine challenge for the diagnosis of OA.
  
  
  METHODS
  We conducted a retrospective study assessing 618 patients who underwent specific inhalation challenges (SICs) for symptoms suggestive of OA between 2000 and 2015. A sputum induction and a methacholine challenge were performed before and after SICs. Blood samples were collected in all subjects before the SICs and in 100 subjects before and after SICs. The diagnostic accuracies of blood and sputum eosinophil counts and methacholine challenge were calculated for diagnosing OA.
  
  
  RESULTS
  The change in blood eosinophil count failed to differentiate workers with positive and negative SICs. The change in sputum eosinophil counts induced by the exposure to the offending agent had the highest diagnostic accuracy (receiver operating characteristic area under the curve: 86% [95% confidence interval: 0.8-0.9, P < .001]) for diagnosing OA compared with changes in concentration of methacholine inducing a 20% fall in forced expiratory volume in 1 second (PC20) and blood eosinophils. Combining a 2-fold or greater decrease in PC20or a 3% or greater increase in sputum eosinophil count achieved a sensitivity of 84% and a specificity of 74% with a negative predictive value of 91% for the diagnosis of OA.
  
  
  CONCLUSIONS
  Blood eosinophil counts do not appear to be an effective aid for diagnosing OA. The performance of both sputum cell count analysis and a methacholine challenge before and after exposure to the offending agent may represent an effective alternative in diagnosing OA when SICs are unavailable.
authors.affiliation: Centre intégré universitaire de santé et des services sociaux du Nord-de-l'Île-de-Montréal, Hôpital du Sacré-Cœur de Montréal, Université de Montréal, Montréal, Quebec, Canada.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Racine
authors.affiliation: Centre intégré universitaire de santé et des services sociaux du Nord-de-l'Île-de-Montréal, Hôpital du Sacré-Cœur de Montréal, Université de Montréal, Montréal, Quebec, Canada.
authors.forename: Roberto
authors.initials: R
authors.lastname: Castano
authors.affiliation: Centre intégré universitaire de santé et des services sociaux du Nord-de-l'Île-de-Montréal, Hôpital du Sacré-Cœur de Montréal, Université de Montréal, Montréal, Quebec, Canada.
authors.forename: André
authors.initials: A
authors.lastname: Cartier
authors.affiliation: Centre intégré universitaire de santé et des services sociaux du Nord-de-l'Île-de-Montréal, Hôpital du Sacré-Cœur de Montréal, Université de Montréal, Montréal, Quebec, Canada. Electronic address: catherine.lemiere@umontreal.ca.
authors.forename: Catherine
authors.initials: C
authors.lastname: Lemiere
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology; D059366:Asthma, Occupational / Q000175:diagnosis* / Q000276:immunology; D015415:Biomarkers / Q000378:metabolism; D001773:Blood Cells / Q000276:immunology*; D001985:Bronchial Provocation Tests; D002452:Cell Count; D004804:Eosinophils / Q000276:immunology*; D005260:Female; D006801:Humans; D007249:Inflammation / Q000175:diagnosis* / Q000276:immunology; D008297:Male; D016210:Methacholine Chloride / Q000008:administration & dosage; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013147:Spirometry; D013183:Sputum / Q000166:cytology* / Q000276:immunology
chemical_list: D000485:Allergens; D015415:Biomarkers; D016210:Methacholine Chloride
keywords: Airway responsiveness; Blood eosinophil count; Occupational asthma; Sputum eosinophil count