Consistent effects of atopy and smoking on FeNO in American and European large population-based samples

Abstract

Introduction: We recently suggested a novel model for prediction of reference FeNO values, by applying the Lambda-Mu-Sigma (LMS) regression models, that may help interpreting FeNO in clinical practice. Aim: To describe the effect of smoking and atopy in two large groups of healthy individuals with the LMS models, and to evaluate the consistency of the results in the two samples. Methods: Caucasian healthy subjects (age 24-75 years) from US NHANES and a Swedish cohort were analysed. Smoking was defined as non-smokers (including former smokers) and current smokers. Atopy was defined by a positive Phadiatop in the Swedish data, and self-reported hay fever symptoms in the past 12 months in the US data. Models were created with the LMS method, imbedded in the Generalized Additive Models for Location, Scale, and Shape (GAMLSS) models, for each sex and corrected for age and height. Results: A total of 6,723 subjects were included, 2,157 from NHANES and 4,566 from Sweden. In NHANES there were 15.5% current smokers, and 15.6% atopics. Current smoking decreased FeNO by 62.5% and 55.1%, whereas atopy increased FeNO by 15.8% and 8.5%, in males and females, respectively. In the Swedish cohort, there were 15.2% current smokers, and 23.2% atopics. The results were similar: current smoking decreased FeNO by 41.8% and 35.0%, whereas atopy increased FeNO by 20.1% and 8.5%, in males and females, respectively. Conclusion: We show consistent effects of active smoking and atopy in large samples of healthy individuals from the US and Europe. These effects seem to be constant and should be accounted for in the interpretation of FeNO in clinical practice.