title: A population-based study of smoking, serum cotinine and exhaled nitric oxide among asthmatics and a healthy population in the USA.
abstract: Fractional concentration of exhaled nitric oxide (FeNO) is recommended by the American Thoracic Society (ATS) as a noninvasive biomarker of airway inflammation. In addition to inflammation, many factors may be associated with FeNO, particularly tobacco exposure; however, only age has been included as an influential factor for children below 12 years. Numerous studies have demonstrated negative associations between tobacco exposure and FeNO levels with self-reported data, but few with an objective assessment of smoking.
  
  
  
  Data from the National Health and Nutrition Examination Survey (NHANES) 2007-2012 were analyzed to examine the association between FeNO and active/passive tobacco. Exposure was assessed by both self-report and serum cotinine levels among 11,160 subjects aged 6-79 years old with asthma, or without any respiratory disease.
  
  
  
  Study results indicated 28.8% lower FeNO, 95% CI [25.2%, 32.3%] and 38.1% lower FeNO, 95% CI: [28.1, 46.2] was observed among healthy and asthmatic participants with serum cotinine in the highest quartile compared to those in the lowest quartile, respectively. Self-reported smoking status and recent tobacco use were also associated with decreased FeNO. Self-reported passive smoking was significantly associated with a 1.0% decrease in FeNO 95% CI [0.0, 2.0] among asthmatic subjects but not among healthy subjects.
  
  
  
  Active smoking, whether measured by self-report or serum cotinine, was associated with decreased FeNO levels. In addition to age, increased attention should be given to tobacco exposure when using FeNO as a biomarker in clinical practice. Additional research is needed to establish reference value of FeNO considering the impact of tobacco exposure.
authors.affiliation: a Department of Epidemiology and Biostatistics , School of Public Health, Texas A&M University , College Station , TX , USA.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Xu
authors.affiliation: b Department of Epidemiology , College of Public Health and Health Professions and College of Medicine, University of Florida , Gainesville , FL , USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Hu
authors.affiliation: c Department of Public Health , East Carolina University, Brody School of Medicine , Greenville , NC, USA.
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Kearney
authors.affiliation: d School of Public Health, Key Laboratory of Public Health Safety of the Ministry of Education and Key Laboratory of Health Technology Assessment of the Ministry of Health, Fudan University , Shanghai , China , and.
authors.forename: Haidong
authors.initials: H
authors.lastname: Kan
authors.affiliation: e Department of Environmental and Occupational Health , School of Public Health, Texas A&M Health Science Center , McAllen , TX , USA.
authors.forename: Genny
authors.initials: G
authors.lastname: Carrillo
authors.affiliation: b Department of Epidemiology , College of Public Health and Health Professions and College of Medicine, University of Florida , Gainesville , FL , USA.
authors.forename: Xinguang
authors.initials: X
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000097:blood / Q000453:epidemiology / Q000378:metabolism*; D002648:Child; D003367:Cotinine / Q000097:blood*; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D009749:Nutrition Surveys; D057566:Self Report; D012907:Smoking / Q000097:blood / Q000453:epidemiology / Q000378:metabolism*; D014028:Tobacco Smoke Pollution; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D014028:Tobacco Smoke Pollution; D009569:Nitric Oxide; D003367:Cotinine
keywords: Asthma; Exhaled nitric oxide; NHANES; Serum cotinine; Smoking