title: Exhaled nitric oxide measure using multiple flows in clinically relevant subgroups of COPD.
abstract: Although there is widespread interest in fractional exhaled nitric oxide (FeNO) as a non-invasive, time and cost effective biomarker for assessing airway inflammation in chronic obstructive pulmonary disease (COPD), its usefulness is still controversial. We examined the FeNO levels in clinically meaningful subgroups of COPD in a group of 91 COPD patients with FEV(1) 17-77% of predicted. Multiple flow rates FeNO at 10, 30, 50, 100 and 200 mL/s were measured and a two-compartment model was used to estimate the diffusion Capacity (D), alveolar NO concentration (Calv) and airway wall NO concentration (Caw). All patients had spirometry, assessment of symptoms with questionnaires and low-dose CT scan as well as assessment of weight and body composition. We examined the following subgroups of COPD: Patients with 1) Severe emphysema, 2) Chronic bronchitis, 3) Frequent exacerbations, 4) Loss of lean body mass and 5) Low fat-free mass index. We used advanced non-linear mixed model adjusted for age and gender. The modelled differences in D, Calv or Caw among COPD subgroups were small and not statistically significant. The analysis showed significant effects of current smoking on Caw and of gender on D and Calv. The results were the same if the advanced non-linear mixed model was substituted by more standard analysis techniques. This study questions the relevance of using FeNO as a biomarker to evaluate local inflammation in COPD and points to a need for developing novel non-invasive biomarkers for research laboratory work and daily clinical practice.
authors.affiliation: Department of Cardiology & Respiratory Medicine, Hvidovre Hospital & Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Nassim
authors.initials: N
authors.lastname: Bazeghi
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Gerds
authors.forename: Esben
authors.initials: E
authors.lastname: Budtz-Jørgensen
authors.forename: Jens
authors.initials: J
authors.lastname: Hove
authors.forename: Jørgen
authors.initials: J
authors.lastname: Vestbo
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D015992:Body Mass Index; D001944:Breath Tests; D018450:Disease Progression; D045853:Exhalation; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D009569:Nitric Oxide / Q000378:metabolism*; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D012907:Smoking / Q000378:metabolism* / Q000503:physiopathology; D013147:Spirometry; D011795:Surveys and Questionnaires
chemical_list: D015415:Biomarkers; D009569:Nitric Oxide