title: Does Ethnicity Influence Fractional Exhaled Nitric Oxide in Healthy Individuals?: A Systematic Review.
abstract: 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.
  
  
  
  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.
  
  
  
  From 62 potential studies, 12 studies were included. One study recruited only children (< 12 years of age), six studies recruited children and/or adolescents, four studies recruited adults only, and a single study involved children, adolescents, and adults. In total, 16 different ethnic populations representing 11 ethnicities were studied. Ethnicity was considered a significant influencing factor in 10 of the included studies. We found the geometric mean Feno to be above the normal healthy range in two studies. We also identified five studies in which at least 5% of participants had Feno results above the age-specific inflammatory ranges.
  
  
  
  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.
authors.affiliation: Queensland University of Technology, Centre for Children's Health Research, South Brisbane, QLD, Australia; Indigenous Respiratory Outreach Care Program, The Prince Charles Hospital, Chermside, QLD, Australia; Department of Respiratory and Sleep Medicine, Lady Cilento Children's Hospital, South Brisbane, QLD, Australia. Electronic address: tamara.blake@health.qld.gov.au.
authors.forename: Tamara L
authors.initials: TL
authors.lastname: Blake
authors.affiliation: Indigenous Respiratory Outreach Care Program, The Prince Charles Hospital, Chermside, QLD, Australia; Department of Respiratory and Sleep Medicine, Lady Cilento Children's Hospital, South Brisbane, QLD, Australia; Child Health Division, Menzies School of Health Research, Darwin, NT, Australia.
authors.forename: Anne B
authors.initials: AB
authors.lastname: Chang
authors.affiliation: Child Health Division, Menzies School of Health Research, Darwin, NT, Australia.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Chatfield
authors.affiliation: Queensland University of Technology, Centre for Children's Health Research, South Brisbane, QLD, Australia.
authors.forename: Helen L
authors.initials: HL
authors.lastname: Petsky
authors.affiliation: Department of Respiratory and Sleep Medicine, Lady Cilento Children's Hospital, South Brisbane, QLD, Australia.
authors.forename: Leanne T
authors.initials: LT
authors.lastname: Rodwell
authors.affiliation: Department of Thoracic Medicine, Royal Brisbane and Women's Hospital, Herston, QLD, Australia.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Brown
authors.affiliation: Indigenous Respiratory Outreach Care Program, The Prince Charles Hospital, Chermside, QLD, Australia.
authors.forename: Deb C
authors.initials: DC
authors.lastname: Hill
authors.affiliation: Queensland University of Technology, Centre for Children's Health Research, South Brisbane, QLD, Australia; Indigenous Respiratory Outreach Care Program, The Prince Charles Hospital, Chermside, QLD, Australia; Department of Respiratory and Sleep Medicine, Lady Cilento Children's Hospital, South Brisbane, QLD, Australia.
authors.forename: Margaret S
authors.initials: MS
authors.lastname: McElrea
mesh_terms: D001944:Breath Tests / Q000379:methods*; D005006:Ethnicity; D006801:Humans; D009569:Nitric Oxide / Q000032:analysis*; D011657:Pulmonary Eosinophilia / Q000175:diagnosis / Q000208:ethnology; D012016:Reference Values
chemical_list: D009569:Nitric Oxide
keywords: ethnicity; exhaled nitric oxide; pulmonary function test