title: Exhaled breath profiling enables discrimination of chronic obstructive pulmonary disease and asthma.
abstract: BACKGROUND
  Chronic obstructive pulmonary disease (COPD) and asthma can exhibit overlapping clinical features. Exhaled air contains volatile organic compounds (VOCs) that may qualify as noninvasive biomarkers. VOC profiles can be assessed using integrative analysis by electronic nose, resulting in exhaled molecular fingerprints (breathprints).
  
  
  OBJECTIVE
  We hypothesized that breathprints by electronic nose can discriminate patients with COPD and asthma.
  
  
  METHODS
  Ninety subjects participated in a cross-sectional study: 30 patients with COPD (age, 61.6 +/- 9.3 years; FEV(1), 1.72 +/- 0.69 L), 20 patients with asthma (age, 35.4 +/- 15.1 years; FEV(1) 3.32 +/- 0.86 L), 20 nonsmoking control subjects (age, 56.7 +/- 9.3 years; FEV(1), 3.44 +/- 0.76 L), and 20 smoking control subjects (age, 56.1 +/- 5.9 years; FEV(1), 3.58 +/- 0.78). After 5 minutes of tidal breathing through an inspiratory VOC filter, an expiratory vital capacity was collected in a Tedlar bag and sampled by electronic nose. Breathprints were analyzed by discriminant analysis on principal component reduction resulting in cross-validated accuracy values (accuracy). Repeatability and reproducibility were assessed by measuring samples in duplicate by two devices.
  
  
  RESULTS
  Breathprints from patients with asthma were separated from patients with COPD (accuracy 96%; P < 0.001), from nonsmoking control subjects (accuracy, 95%; P < 0.001), and from smoking control subjects (accuracy, 92.5%; P < 0.001). Exhaled breath profiles of patients with COPD partially overlapped with those of asymptomatic smokers (accuracy, 66%; P = 0.006). Measurements were repeatable and reproducible.
  
  
  CONCLUSIONS
  Molecular profiling of exhaled air can distinguish patients with COPD and asthma and control subjects. Our data demonstrate a potential of electronic noses in the differential diagnosis of obstructive airway diseases and in the risk assessment in asymptomatic smokers. Clinical trial registered with www.trialregister.nl (NTR 1282).
authors.affiliation: Department of Respiratory Medicine, F5-260, Academic Medical Centre, University of Amsterdam, P.O. Box 22700, Amsterdam NL-1100 DE, The Netherlands. N.Fens@amc.nl
authors.forename: Niki
authors.initials: N
authors.lastname: Fens
authors.forename: Aeilko H
authors.initials: AH
authors.lastname: Zwinderman
authors.forename: Marc P
authors.initials: MP
authors.lastname: van der Schee
authors.forename: Selma B
authors.initials: SB
authors.lastname: de Nijs
authors.forename: Erica
authors.initials: E
authors.lastname: Dijkers
authors.forename: Albert C
authors.initials: AC
authors.lastname: Roldaan
authors.forename: David
authors.initials: D
authors.lastname: Cheung
authors.forename: Elisabeth H
authors.initials: EH
authors.lastname: Bel
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Sterk
mesh_terms: D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001249:Asthma / Q000175:diagnosis* / Q000188:drug therapy; D015415:Biomarkers / Q000032:analysis; D001944:Breath Tests / Q000295:instrumentation* / Q000379:methods*; D003430:Cross-Sectional Studies; D045853:Exhalation; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000188:drug therapy; D015203:Reproducibility of Results; D012907:Smoking; D055549:Volatile Organic Compounds / Q000032:analysis; D055815:Young Adult
chemical_list: D000305:Adrenal Cortex Hormones; D015415:Biomarkers; D055549:Volatile Organic Compounds