title: Diagnostic accuracy of the C-urea breath test in children: adjustment of the cut-off value according to age.
abstract: OBJECTIVE
  The (13)C-urea breath test ((13)C-UBT) is a reliable non-invasive method of diagnosing Helicobacter pylori infection in adults and children. However, only a few validation studies have been performed on the (13)C-UBT in very young children. The purpose of the present study was to evaluate the diagnostic accuracy of the (13)C-UBT according to age, and to determine the optimal cut-off value in children.
  
  
  METHODS
  A total of 307 (13)C-UBT were performed in 274 children. All were compared with the results of endoscopic biopsy-based methods to confirm H. pylori infection. Seventy-five milligrams of (13)C-urea was ingested without a test meal. Two breath samples were collected at 0 and 30 min. The optimal cut-off value of the (13)C-UBT was assessed by determining the sensitivity, specificity, false negative, and false positive results, at cut-off values ranging from 2.0 to 10.0 per thousand.
  
  
  RESULTS
  The delta over baseline (DOB) values of the (13)C-UBT showed a significant negative correlation with age in both the H. pylori-positive group (r = -0.309; P = 0.005) and the H. pylori-negative group (r = -0.162; P = 0.015). High false positive results and low specificity were noted in children aged 6 years or less compared with children older than 6 years at a cut-off value of 4.0 per thousand (false positives; 8.3%vs 0.85%, specificity; 89.8%vs 98.8%). After adjusting the cut-off value, the optimal cut-off values were found to be 4.0 per thousand in children older than 6 years and 7.0 per thousand in children aged 6 years or less.
  
  
  CONCLUSIONS
  The cut-off value of the (13)C-UBT recommended regardless of age must be adjusted in preschool children to reduce the false positive results.
authors.affiliation: Department of Pediatrics, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors.forename: Hye Ran
authors.initials: HR
authors.lastname: Yang
authors.forename: Jeong Kee
authors.initials: JK
authors.lastname: Seo
mesh_terms: D000293:Adolescent; D001944:Breath Tests / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005773:Gastroscopy; D016481:Helicobacter Infections / Q000175:diagnosis*; D016480:Helicobacter pylori / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014508:Urea
chemical_list: D014508:Urea