title: Both exhaled nitric oxide and blood eosinophil count were associated with mild allergic asthma only in non-smokers.
abstract: BACKGROUND
  The fractional exhaled nitric oxide (FENO) and the blood eosinophil count (B-eos) are markers of eosinophilic inflammation used in the diagnosis and management of asthma. The relationships between smoking cigarette and both FENO and B-eos are complex and raise questions about the association between these markers and asthma in smokers.
  
  
  OBJECTIVE
  To determine the relationships between both FENO and B-eos on one hand and asthma and atopy on the other, according to smoking status.
  
  
  METHODS
  FENO and B-eos were measured in, respectively, 1579 and 1496 of the 1607 middle-aged adults randomly selected from the general population in the cross-sectional ELISABET survey. Allergic asthma was defined as asthma (a self-report of physician-diagnosed asthma, and wheezing in the previous 12 months or the use of asthma medications) with atopy (allergic rhinitis or hayfever in the previous 12 months, or a previous positive prick test or allergen desensitization therapy). Non-allergic asthma was defined as asthma without atopy.
  
  
  RESULTS
  The analysis included 812 (51.4%) never, 473 (30%) former and 294 (18.6%) current smokers. A total of 490 (32%) participants were atopic, 80 (5.1%) had allergic asthma, and 31 (2%) had non-allergic asthma. Only 16.2% (18/111) of asthmatics were treated with glucocorticoid inhalants, suggesting that among them a majority of participants had mild asthma. A positive interaction between smoking status and allergic asthma was observed in multivariate models explaining FENO (P = 0.003) and B-eos (P = 0.001). Thus, compared to those without allergic asthma, participants with allergic asthma had higher FENO values (+ 63.4%, 95% CI = [39; 92]) and higher B-eos (+ 63.2% [38.2; 92.7]) in never and former smokers, but not in current smokers. Lastly, an analysis of receiver-operating characteristic curves showed that each of the two markers was able to discriminate moderately allergic asthma but only in non-smokers.
  
  
  CONCLUSIONS
  FENO and B-eos were associated with the presence of mild allergic asthma only in non-smokers, not in current smokers. These findings raise questions about the clinical value of FENO and B-eos in smokers.
authors.affiliation: Faculté de Médecine Henri Warembourg, University of Lille, Lille Cedex, France.|University Hospital of Lille, Lille, France.|Pasteur Institute of Lille, INSERM U1167 RID-AGE, Lille, France.
authors.forename: J
authors.identifier: http://orcid.org/0000-0002-7516-4670
authors.initials: J
authors.lastname: Giovannelli
authors.affiliation: Faculté de Médecine Henri Warembourg, University of Lille, Lille Cedex, France.|University Hospital of Lille, Lille, France.
authors.forename: N
authors.initials: N
authors.lastname: Chérot-Kornobis
authors.affiliation: Faculté de Médecine Henri Warembourg, University of Lille, Lille Cedex, France.|University Hospital of Lille, Lille, France.
authors.forename: S
authors.initials: S
authors.lastname: Hulo
authors.affiliation: Pasteur Institute of Lille, INSERM U1167 RID-AGE, Lille, France.
authors.forename: A
authors.initials: A
authors.lastname: Ciuchete
authors.affiliation: Faculté de Médecine Henri Warembourg, University of Lille, Lille Cedex, France.|Pasteur Institute of Lille, INSERM U1167 RID-AGE, Lille, France.
authors.forename: G
authors.initials: G
authors.lastname: Clément
authors.affiliation: Faculté de Médecine Henri Warembourg, University of Lille, Lille Cedex, France.|University Hospital of Lille, Lille, France.|Pasteur Institute of Lille, INSERM U1167 RID-AGE, Lille, France.
authors.forename: P
authors.initials: P
authors.lastname: Amouyel
authors.affiliation: Faculté de Médecine Henri Warembourg, University of Lille, Lille Cedex, France.|University Hospital of Lille, Lille, France.
authors.forename: R
authors.initials: R
authors.lastname: Matran
authors.affiliation: Faculté de Médecine Henri Warembourg, University of Lille, Lille Cedex, France.|University Hospital of Lille, Lille, France.|Pasteur Institute of Lille, INSERM U1167 RID-AGE, Lille, France.
authors.forename: L
authors.initials: L
authors.lastname: Dauchet
mesh_terms: D000328:Adult; D001249:Asthma / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism*; D015415:Biomarkers; D001944:Breath Tests; D004804:Eosinophils / Q000276:immunology / Q000473:pathology; D045853:Exhalation; D005260:Female; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000096:biosynthesis*; D011159:Population Surveillance; D012307:Risk Factors; D012720:Severity of Illness Index; D012907:Smoking / Q000009:adverse effects
chemical_list: D015415:Biomarkers; D009569:Nitric Oxide
keywords: airway inflammation; blood eosinophil count; fractional exhaled nitric oxide; interaction; smoking status; tobacco