title: Validity of Fractional Exhaled Nitric Oxide in Diagnosis of Corticosteroid-Responsive Cough.
abstract: BACKGROUND
  Whether fractional exhaled nitric oxide (FeNO) measurement alone or combined with sputum eosinophil and atopy is useful in predicting corticosteroid-responsive cough (CRC) and non-CRC (NCRC) is not clear.
  
  
  METHODS
  A total of 244 patients with chronic cough and 59 healthy subjects as control were enrolled. The causes of chronic cough were confirmed according to a well-established diagnostic algorithm. FeNO measurement and induced sputum for differential cell were performed in all subjects.
  
  
  RESULTS
  CRC occurred in 139 (57.0%) patients and NCRC occurred in 105. The FeNO level in CRC significantly correlated with sputum eosinophils (rs = 0.583, P < .01). The median (quarter) of FeNO level in CRC was significantly higher than NCRC (32.0 ppb [19.0-65.0 ppb] vs 15.0 ppb [11.0-22.0 ppb], P < .01). FeNO of 31.5 ppb had a sensitivity and specificity of 54.0% and 91.4%, respectively, in predicting CRC from chronic cough, with a positive predictive value of 89.3% and a negative predictive value of 60.0%. If the patients had a combination of low level of FeNO ( < 22.5 ppb), normal sputum eosinophil ( < 2.5%), and absence of atopy, the sensitivity and specificity would be 30.3% and 93.5% for predicting NCRC.
  
  
  CONCLUSIONS
  In our cohort, a high level (≥ 31.5 ppb) of FeNO indicates more likelihood of CRC, but the sensitivity is insufficient to rule out a diagnosis of CRC. A combination of low-level FeNO, normal sputum eosinophil, and absence of atopy suggests a lower likelihood of CRC.
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, P.R. China.
authors.forename: Fang
authors.initials: F
authors.lastname: Yi
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, P.R. China.
authors.forename: Ruchong
authors.initials: R
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, P.R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, P.R. China.
authors.forename: Danyuan
authors.initials: D
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, P.R. China.
authors.forename: Lina
authors.initials: L
authors.lastname: Han
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, P.R. China.
authors.forename: Baojuan
authors.initials: B
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, P.R. China.
authors.forename: Siqi
authors.initials: S
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, P.R. China.
authors.forename: Qiaoli
authors.initials: Q
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, P.R. China. Electronic address: klai@163.com.
authors.forename: Kefang
authors.initials: K
authors.lastname: Lai
mesh_terms: D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D001249:Asthma / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D001944:Breath Tests; D016022:Case-Control Studies; D002908:Chronic Disease; D015331:Cohort Studies; D003371:Cough / Q000175:diagnosis* / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology; D004802:Eosinophilia / Q000150:complications / Q000175:diagnosis*; D004804:Eosinophils / Q000166:cytology*; D005260:Female; D005541:Forced Expiratory Volume; D005764:Gastroesophageal Reflux / Q000150:complications / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013183:Sputum / Q000166:cytology*; D014797:Vital Capacity; D055815:Young Adult
chemical_list: D000305:Adrenal Cortex Hormones; D009569:Nitric Oxide
keywords: atopy; chronic cough; corticosteroids-responsive cough; eosinophil; fractional exhaled nitric oxide