title: Diagnostic value and influencing factors of fractional exhaled nitric oxide in suspected asthma patients.
abstract: OBJECTIVE
  To explore the critical value and possible influencing factors of fractional exhaled nitric oxide (FeNO) in suspected asthma patients.
  
  
  METHODS
  923 suspected asthmatics consecutively referred to our hospital during December 2012 to July 2014 were selected. All cases were carried out FeNO measurement at first; next, spirometry, bronchoprovocation tests or bronchodilation tests were used to confirm or exclude asthma. Receiver operating characteristic curve (ROC) was used to determine the best cut-off value of FeNO for asthma diagnosis.
  
  
  RESULTS
  In bronchoprovocation test, 125 cases were diagnosed as asthma, other 283 were non-asthmatics. FeNO levels of asthmatics were significantly higher than non-asthmatics (median, 64.8 ppb vs. 27.9 ppb, P<0.01). In this group of patients, 64 ppb was the best cut-off value of FeNO to identify asthma with sensitivity of 52.0% and specificity of 94.35%. In bronchodilation test, 185 patients were diagnosed as asthma, other 330 were non-asthmatics. FeNO levels of asthmatics were significantly higher than non-asthmatics (median, 60.6 ppb vs. 29.05 ppb, P<0.01). In bronchodilation test patients, 41 ppb was the best cut-off value of FeNO to identify asthma with sensitivity of 72.43% and specificity of 74.85%. Influencing factors analysis showed that sex was an independent factor affecting patients' FeNO level.
  
  
  CONCLUSIONS
  FeNO was an effective auxiliary diagnosis method for bronchial asthma. 64 ppb and 41 ppb was the best cut-off value of FeNO to identify asthma in bronchoprovocation test or bronchodilation test, respectively. Sex was an independent factor affecting patients' FeNO level.
authors.affiliation: Department of Respiratory Medicine, Daping Hospital, Third Military Medical University Chongqing 400042, China.
authors.forename: Yubo
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Respiratory Medicine, Daping Hospital, Third Military Medical University Chongqing 400042, China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Respiratory Medicine, Daping Hospital, Third Military Medical University Chongqing 400042, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Han
authors.affiliation: Department of Respiratory Medicine, Daping Hospital, Third Military Medical University Chongqing 400042, China.
authors.forename: Wenhui
authors.initials: W
authors.lastname: Lei
authors.affiliation: Department of Respiratory Medicine, Daping Hospital, Third Military Medical University Chongqing 400042, China.
authors.forename: Zhongyan
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Respiratory Medicine, Daping Hospital, Third Military Medical University Chongqing 400042, China.
authors.forename: Kunlin
authors.initials: K
authors.lastname: Li
authors.affiliation: Department of Respiratory Medicine, Daping Hospital, Third Military Medical University Chongqing 400042, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Kang
authors.affiliation: Department of Respiratory Medicine, Daping Hospital, Third Military Medical University Chongqing 400042, China.
authors.forename: Hengyi
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Respiratory Medicine, Daping Hospital, Third Military Medical University Chongqing 400042, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: He
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D001249:Asthma / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology*; D015415:Biomarkers / Q000378:metabolism; D001944:Breath Tests; D001985:Bronchial Provocation Tests; D001993:Bronchodilator Agents / Q000008:administration & dosage; D045853:Exhalation; D005260:Female; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D011237:Predictive Value of Tests; D012372:ROC Curve; D012720:Severity of Illness Index; D012737:Sex Factors; D013147:Spirometry; D055815:Young Adult
chemical_list: D015415:Biomarkers; D001993:Bronchodilator Agents; D009569:Nitric Oxide
keywords: Fractional exhaled nitric oxide; asthma diagnosis; influencing factors