title: Guideline-recommended fractional exhaled nitric oxide is a poor predictor of health-care use among inner-city children and adolescents receiving usual asthma care.
abstract: BACKGROUND
  American Thoracic Society guidelines support using fractional exhaled nitric oxide (FENO) measurements in patients with asthma and highlight gaps in the evidence base. Little is known about the use of FENO levels to predict asthma exacerbations among high-risk, urban, minority populations receiving usual care.
  
  
  METHODS
  Children with persistent asthma (n = 138) were enrolled in a prospective, observational cohort study and skin tested at baseline (a wheal ≥ 3 mm indicated a positive skin-prick test). FENO levels, lung function, and asthma-related health-care use were assessed at baseline and every 3 months thereafter for 1 year. Relationships between FENO levels and health-care use in the subsequent 3 months were examined. Final models accounted for repeated outcome measures and were adjusted for age, sex, and lung function.
  
  
  RESULTS
  The mean age of the children was 11 years (range, 5-17 years), and most were male (57%), black (91%), and atopic (90%). At baseline, the median FENO level was 31.5 parts per billion (interquartile range, 16-61 ppb) and mean FEV1/FVC was 80.7% (SD, ± 9.6%). There were 237 acute asthma-related health-care visits, 105 unscheduled doctor visits, 125 ED visits, and seven hospitalizations during the follow-up period. FENO level was not a significant predictor of acute visits, ED visits, unscheduled doctor visits, or hospitalization in either unadjusted or adjusted analyses. Use of recommended cut points did not improve the predictive value of the FENO level (positive predictive value, 0.6%-32.8%) nor did application of the guideline-based algorithm to assess change over time.
  
  
  CONCLUSIONS
  FENO level may not be a clinically useful predictor of health-care use for asthma exacerbations in urban minority children with asthma.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD. Electronic address: mmccor16@jhmi.edu.
authors.forename: Meredith C
authors.initials: MC
authors.lastname: McCormack
authors.affiliation: Division of Pediatric Allergy and Immunology, Johns Hopkins University, Baltimore, MD.
authors.forename: Charles
authors.initials: C
authors.lastname: Aloe
authors.affiliation: Division of Pediatric Allergy and Immunology, Johns Hopkins University, Baltimore, MD.
authors.forename: Jean
authors.initials: J
authors.lastname: Curtin-Brosnan
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Gregory B
authors.initials: GB
authors.lastname: Diette
authors.affiliation: Bloomberg School of Public Health, Department of Environmental Health Sciences, Johns Hopkins University, Baltimore, MD.
authors.forename: Patrick N
authors.initials: PN
authors.lastname: Breysse
authors.affiliation: Division of Pediatric Allergy and Immunology, Johns Hopkins University, Baltimore, MD.
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Matsui
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D001944:Breath Tests; D002648:Child; D002675:Child, Preschool; D045853:Exhalation; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*; D017410:Practice Guidelines as Topic; D011446:Prospective Studies; D011785:Quality Assurance, Health Care; D014505:Urban Population
chemical_list: D009569:Nitric Oxide