title: Prognostic value of bronchial provocation and FENO measurement for asthma diagnosis--results of a delayed type of diagnostic study.
abstract: OBJECTIVE
  To compare the prognostic value of FENO with bronchoprovocation testing when the clinical course within the first year after assessment was taken into account; to compare the prognostic values with respect to eosinophilic versus non-eosinophilic inflammatory pattern.
  
  
  METHODS
  Cross-sectional diagnostic study with a delayed-type reference standard in 393 patients attending a private practice of pneumologists with complaints suspicious of obstructive airway disease.
  
  
  METHODS
  FENO measurement. Reference standard: ratio FEV1/VC or airway resistance assessed by body plethysmography, with additional bronchoprovocation or bronchodilator testing, as well as spontaneous sputum (smear slides). This was combined with a follow-up evaluation by a structured interview after 12 months.
  
  
  RESULTS
  302 (76.8%) patients were reached for follow-up. Regarding asthma diagnosis, the area under the curve (AUC) for FENO was 0.603 (95%CI 0.528-0.677) for the whole group. With eosinophilic asthma as target, AUC increased (0.819 (95%CI 0.703-0.934)) and exceeded that of bronchoprovocation (0.711 (95%CI 0.584-0.874)). FENO showed no diagnostic value in non-eosinophilic asthma. In patients reporting wheezing and allergic rhinitis at the initial assessment, its positive predictive value was 90.9% (95%CI 62.3%-98.4) at a cut-off of 45 ppb, and 100% (95%CI 56.6-100%) at 81 ppb.
  
  
  CONCLUSIONS
  FENO bears limited information when measured non-specifically in primary care, but is useful for diagnosing eosinophilic asthma. If sputum is not available, information on wheezing and rhinitis can narrow down the range of patients in whom FENO is informative. Moreover, the evaluation of the clinical value of FENO benefits from taking into account follow-up data to confirm the diagnosis.
authors: Institute of General Practice, University Hospital Klinikum rechts der Isar, Technische Universität München, Germany. Electronic address: antonius.schneider@tum.de.
authors: Antonius
authors: A
authors: Schneider
authors: Institute of General Practice, University Hospital Klinikum rechts der Isar, Technische Universität München, Germany.
authors: Bernhard
authors: B
authors: Faderl
authors: Institute of General Practice, University Hospital Klinikum rechts der Isar, Technische Universität München, Germany.
authors: Johannes
authors: J
authors: Schwarzbach
authors: Lungenclinic Grosshansdorf, Großhansdorf, Germany.
authors: Lutz
authors: L
authors: Welker
authors: Institute of General Practice, University Hospital Klinikum rechts der Isar, Technische Universität München, Germany.
authors: Marlies
authors: M
authors: Karsch-Völk
authors: Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine, Ludwig-Maximilians-University, Munich, Germany.
authors: Rudolf A
authors: RA
authors: Jörres
mesh_terms: D000328:Adult; D001249:Asthma / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology*; D001985:Bronchial Provocation Tests / Q000379:methods; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D010993:Plethysmography, Whole Body / Q000379:methods; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D012129:Respiratory Function Tests; D018570:Risk Assessment; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013183:Sputum / Q000166:cytology / Q000378:metabolism*; D014797:Vital Capacity
chemical_list: D009569:Nitric Oxide
keywords: Asthma; Eosinophilic; Nitric oxide; Non-eosinophilic; Sensitivity; Specificity