title: Measurement of Fractional Exhaled Nitric Oxide as a Marker of Disease Activity in Inflammatory Bowel Disease.
abstract: OBJECTIVE
  Definitive diagnosis of IBD requires endoscopic and pathologic confirmation. These tools are also used to classify disease activity. Our aim was to determine if the fractional exhaled nitric oxide (FeNO) could be utilized to screen for IBD and assess for disease activity.
  
  
  METHODS
  We matched weighted IBD cases and controls from the 2009-2010 NHANES dataset. All subjects underwent measurement of FeNO using standardized techniques. We assessed for potential confounders for FeNO measurement including age, height, and asthma. For IBD subjects, we used the presence of diarrhea, fatigue, and weight loss as a proxy for IBD activity. Laboratory parameters examined to estimate disease activity included anemia (≤ 10 g/dl), iron deficiency (ferritin ≤ 20 ng/ml), hypoalbuminemia (≤ 3.2 g/dl), and CRP (≥ 1.1 mg/dl).
  
  
  RESULTS
  The weighted sample represented 199,414,901 subjects. The weighted prevalence of IBD was 2,084,895 (1.0%). IBD subjects had nearly the same FeNO level as those without IBD (17.0 ± 16.2 vs. 16.7 ± 14.5 ppb). The odds of a FeNO > 25 ppb was half (OR=0.501; 95% CI 0.497-0.504) for subjects with IBD compared to those without IBD after controlling for confounders. The AUROC curve for FeNO was 0.47 (0.35-0.59). FeNO levels were not higher in patients with laboratory values suggestive of active disease. FeNO levels were higher in IBD patients with diarrhea, rectal urgency, and fatigue but were lower in those with unintentional weight loss.
  
  
  CONCLUSIONS
  Measurement of FeNO does not appear to be useful to screen for IBD or assess disease activity.
authors.affiliation: Department of Medicine, Temple University School of Medicine, Philadelphia, PA.
authors.forename: Erkanda
authors.initials: E
authors.lastname: Ikonomi
authors.affiliation: Temple Inflammatory Bowel Disease Program, Temple University School of Medicine, Philadelphia, PA.
authors.forename: Robin D
authors.initials: RD
authors.lastname: Rothstein
authors.affiliation: Temple Inflammatory Bowel Disease Program, Temple University School of Medicine, Philadelphia, PA.
authors.forename: Adam C
authors.initials: AC
authors.lastname: Ehrlich
authors.affiliation: Temple Inflammatory Bowel Disease Program, Temple University School of Medicine, Philadelphia, PA.
authors.forename: Frank K
authors.initials: FK
authors.lastname: Friedenberg
keywords: Biomarker; Crohn’s disease; Inflammation; Inflammatory bowel disease; Nitric oxide; Ulcerative colitis