title: Exhaled nitric oxide in school children: Searching for the lost variability.
abstract: OBJECTIVE
  The factors - including asthma and rhinoconjunctivitis - which influence FeNO values in a general population of school children have been studied in order to know to what extent the variability of those values can be explained.
  
  
  METHODS
  FeNO was measured in a population of 240 school children aged 6-12 years by means of a Niox-Mino™ device in a standardised way. Parents filled in an ISAAC-validated questionnaire of symptoms and environmental factors. Diagnoses were checked against clinical records. Height and weight were measured. A multivariate regression analysis including all variables in the questionnaire was performed, which was followed by two Xi stepwise tests in order to build a predictive model which included the main variables influencing FeNO values.
  
  
  RESULTS
  Among the 240 children, 10 suffered from asthma, 16 from rhinoconjunctivitis and 15 from both conditions. FeNO values (GM±GSD) in children with rhinoconjunctivitis (19.61±1.20ppb), with asthma (18.62±1.32ppb), and with both conditions (17.62±1.19ppb) tended to be significantly higher than control children (11.42±1.04ppb), p=0.0016, p=0.08 and p=0.01, respectively. The different predictive models were able to explain only 20-27% of FeNO variability.
  
  
  CONCLUSIONS
  The proportion of FeNO inter-individual variability which can be explained by individual (including suffering from asthma or rhinoconjunctivitis), family, and environmental factors is very low (20-27%). This could have implications on the usefulness of FeNO as a diagnostic tool in asthma.
authors.affiliation: Department of General Pediatrics, Arrixaca University Children's Hospital, University of Murcia, Murcia, Spain. Electronic address: pat.garcia.marcos@gmail.com.
authors.forename: P W
authors.initials: PW
authors.lastname: Garcia-Marcos
authors.affiliation: Emergency Department, Los Arcos del Mar Menor University Hospital, San Javier, Murcia, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Soriano-Pérez
authors.affiliation: Department of General Pediatrics, Arrixaca University Children's Hospital, University of Murcia, Murcia, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Perez-Fernández
authors.affiliation: Department of Pediatric Respiratory Medicine, Los Arcos del Mar Menor University Hospital, San Javier, Murcia, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Valverde-Molina
mesh_terms: D001249:Asthma / Q000175:diagnosis*; D015415:Biomarkers / Q000032:analysis; D001944:Breath Tests; D002648:Child; D003233:Conjunctivitis, Allergic / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007249:Inflammation / Q000175:diagnosis; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*; D011237:Predictive Value of Tests; D065631:Rhinitis, Allergic / Q000175:diagnosis*; D013030:Spain; D011795:Surveys and Questionnaires
chemical_list: D015415:Biomarkers; D009569:Nitric Oxide
keywords: Asthma; Atopy; Epidemiology; FeNO; Rhinoconjunctivitis; School children