Abstract
BackgroundThe 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.MethodsWe 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.ResultsOf 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.ConclusionsFeNO had limited accuracy to identify atopy among the general population; however, it may be a useful indicator of atopic phenotype among asthmatics.
Highlights
The fractional exhaled nitric oxide (FeNO) is a quantitative, noninvasive and safe measure of airways inflammation that may complement the assessment of asthma
We did not observe major differences between those with and without incomplete assessments (Table 1); we were more successful in obtaining both FeNO and an allergy skin tests among participants in Tumbes vs. Lima (p
Mean FeNO was higher in atopics than in non-atopics (17.6 ppb vs. 11.6 ppb; p
Summary
The fractional exhaled nitric oxide (FeNO) is a quantitative, noninvasive and safe measure of airways inflammation that may complement the assessment of asthma. FeNO may be a useful marker in the assessment of asthma status and control [3,4] It has shown potential promise as a non-invasive biomarker for asthma because it is a simple, well tolerated test with no risk to the participant [5] and it provides real-time, reproducible results in children aged ≥4 years [1,2,3,6,7,8,9]. For these reasons, FeNO has been recently recommended as a clinical endpoint for the charac-. The fact that atopy cannot always be identified using an allergy skin test [21], and the underlying risks involved in the determination of allergic skin sensitization increases the importance of studying the validity of FeNO as a simple, non-invasive biomarker for atopy [2,4,17]
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