Does Ethnicity Influence Fractional Exhaled Nitric Oxide in Healthy Individuals?

Background Fractional exhaled nitric oxide (Feno) is used clinically as a biomarker of eosinophilic airway inflammation. Awareness of the factors influencing Feno values is important for valid clinical interpretation. Methods We undertook a systematic review of PubMed, Cochrane Library, Scopus, and Web of Science databases and reference lists of included articles to evaluate whether ethnicity influences Feno values, and to determine if this influence affects clinical interpretation according to current guidelines. We included all studies that performed online Feno measurements on at least 25 healthy, non-Caucasian individuals, and examined the effect of ethnicity on Feno. Results From 62 potential studies, 12 studies were included. One study recruited only children ( Conclusions Ethnicity influences Feno values, and for some ethnic groups this influence likely affects clinical interpretation according to current guidelines. There is a need to establish healthy Feno reference ranges for specific ethnic groups to improve clinical application.