title: Role of exhaled nitric oxide as a predictor of atopy.
abstract: BACKGROUND
  The fractional exhaled nitric oxide (FeNO) is a quantitative, noninvasive and safe measure of airways inflammation that may complement the assessment of asthma. Elevations of FeNO have recently been found to correlate with allergic sensitization. Therefore, FeNO may be a useful predictor of atopy in the general population. We sought to determine the diagnostic accuracy of FeNO in predicting atopy in a population-based study.
  
  
  METHODS
  We conducted a cross-sectional study in an age- and sex- stratified random sample of 13 to 15 year-olds in two communities in Peru. We asked participants about asthma symptoms, environmental exposures and sociodemographics, and underwent spirometry, assessment of FeNO and an allergy skin test. We used multivariable logistic regression to model the odds of atopy as a function of FeNO, and calculated area-under-the-curves (AUC) to determine the diagnostic accuracy of FeNO as a predictor of atopy.
  
  
  RESULTS
  Of 1441 recruited participants, 1119 (83%) completed all evaluations. Mean FeNO was 17.6 ppb (SD=0.6) in atopics and 11.6 ppb (SD=0.8) in non-atopics (p<0.001). In multivariable analyses, a FeNO>20 ppb was associated with an increase in the odds of atopy in non-asthmatics (OR=5.3, 95% CI 3.3 to 8.5) and asthmatics (OR=16.2, 95% CI 3.4 to 77.5). A FeNO>20 ppb was the best predictor for atopy with an AUC of 68% (95% CI 64% to 69%). Stratified by asthma, the AUC was 65% (95% CI 61% to 69%) in non-asthmatics and 82% (95% CI 71% to 91%) in asthmatics.
  
  
  CONCLUSIONS
  FeNO had limited accuracy to identify atopy among the general population; however, it may be a useful indicator of atopic phenotype among asthmatics.
authors: Asociación Benéfica PRISMA, Lima, Peru.
authors: Karina M
authors: KM
authors: Romero
authors: Colin L
authors: CL
authors: Robinson
authors: Lauren M
authors: LM
authors: Baumann
authors: Robert H
authors: RH
authors: Gilman
authors: Robert G
authors: RG
authors: Hamilton
authors: Nadia N
authors: NN
authors: Hansel
authors: William
authors: W
authors: Checkley
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000032:analysis; D001944:Breath Tests / Q000379:methods*; D003430:Cross-Sectional Studies; D045853:Exhalation; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000175:diagnosis* / Q000453:epidemiology / Q000378:metabolism*; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*; D010568:Peru / Q000453:epidemiology; D015995:Prevalence; D015203:Reproducibility of Results; D018570:Risk Assessment; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D009569:Nitric Oxide
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