title: Long-term follow-up of 13C-urea breath test results after Helicobacter pylori eradication: frequency and significance of borderline delta13CO2 values.
abstract: BACKGROUND
  The precise choice of cut-off point for the 13C-urea breath test to define whether it is positive or negative represents a controversial issue.
  
  
  OBJECTIVE
  To quantify the 13C-urea breath test result for several years following Helicobacter pylori eradication, and to evaluate the frequency and the significance of borderline delta13CO2 values.
  
  
  METHODS
  Two-hundred H. pylori eradicated patients confirmed by 13C-urea breath test (100 mg of urea, citric acid), and having had repeated this test yearly up to 5 years, were studied. Delta13CO2 values between 2 and 5/1000 were considered as borderline results.
  
  
  RESULTS
  Eight H. pylori recurrences were observed during 406 patient-years of follow-up (1.97% yearly). In two of eight reinfected patients, the reinfection was preceded by a negative delta13CO2 value >2/1000. Borderline delta13CO2 values were detected in 4% of the 606 urea breath tests performed, and in 25% when only patients in whom H. pylori recurrence was detected in subsequent urea breath tests were included (P < 0.05). The negative-predictive value of a post-treatment delta13CO2 >2/1000 for the diagnosis of H. pylori recurrence was 99%.
  
  
  CONCLUSIONS
  Positive and negative urea breath test results tend to cluster outside the range between 2/1000 and 5/1000. Nevertheless, a borderline urea breath test delta value (e.g. very close to the selected cut-off point) should be interpreted cautiously, and the result should probably be confirmed either by repeating the urea breath test or by other diagnostic methods. On the contrary, a delta13CO2 value <2/1000 very confidently confirms H. pylori eradication.
authors.affiliation: Gastroenterology Unit, La Princesa University Hospital, Autonomous University, Madrid, Spain. gisbert@meditex.es
authors.forename: J P
authors.initials: JP
authors.lastname: Gisbert
authors.forename: D
authors.initials: D
authors.lastname: Olivares
authors.forename: I
authors.initials: I
authors.lastname: Jimenez
authors.forename: J M
authors.initials: JM
authors.lastname: Pajares
mesh_terms: D001944:Breath Tests / Q000379:methods*; D002247:Carbon Isotopes; D005260:Female; D005500:Follow-Up Studies; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000188:drug therapy; D016480:Helicobacter pylori / Q000302:isolation & purification*; D006801:Humans; D008134:Long-Term Care / Q000379:methods; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012008:Recurrence; D012680:Sensitivity and Specificity; D014508:Urea
chemical_list: D002247:Carbon Isotopes; D014508:Urea