title: Longitudinal measurements of exhaled nitric oxide in children-what is a significant change in FE(NO) ?
abstract: BACKGROUND
  The principle aim of this study was to describe the variability of exhaled nitric oxide (FE(NO)) concentrations over 10 months in children with and without asthma.
  
  
  METHODS
  FE(NO) was measured on six occasions at 2-month intervals in a community-based cohort of children with and without asthma.
  
  
  RESULTS
  There were 178 children recruited, 47 had asthma, mean age 9.6 yr. A total of 851 FE(NO) measurements were made. The change in FE(NO) values was positively associated with the initial FE(NO) concentration (p < 0.001) and duration between paired measurements (p = 0.016) but not asthma diagnosis; there was an interaction between initial FE(NO) and duration between measurements. As an approximate rule-of-thumb, a child's FE(NO) may rise by up to 100% of their current FE(NO) over 2 and 4 months, independent of asthma.
  
  
  CONCLUSIONS
  Both the baseline FE(NO) and interval between repeated FE(NO) measurements are relevant to FE(NO) values, independent of asthma. These findings may be useful to clinical interpretation of FE(NO) results in children.
authors.affiliation: Child Health, University of Aberdeen, Aberdeen, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Cutts
authors.forename: Steve
authors.initials: S
authors.lastname: Turner
mesh_terms: D001249:Asthma / Q000175:diagnosis*; D001944:Breath Tests / Q000379:methods*; D002648:Child; D045853:Exhalation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D044382:Population Groups; D011379:Prognosis; D013997:Time Factors
chemical_list: D009569:Nitric Oxide
keywords: asthma; child; longitudinal study; nitric oxide