title: Stool antigen assay (HpSA) is less reliable than urea breath test for post-treatment diagnosis of Helicobacter pylori infection.
abstract: BACKGROUND
  The diagnostic yield of the stool antigen test (HpSA) in evaluating the results of Helicobacter pylori eradication therapy is controversial, but many studies have used only the 13C-urea breath test (13C-UBT) as a gold standard which has greatly reduced their relevance.
  
  
  OBJECTIVE
  To compare the reliability of HpSA and 13C-UBT in patients post-treatment using biopsy-based methods as reference tests.
  
  
  METHODS
  A total of 100 consecutive dyspeptic patients (42 male and 58 female; mean age, 56 +/- 18 years) were enrolled in our study. All patients were H. pylori positive on the basis of at least two biopsy-based methods, and underwent 1 week of treatment with various triple therapies. They were again endoscoped 4 weeks after completing therapy and six biopsy specimens were taken from the gastric antrum and corpus for rapid urease test, histology and culture. HpSA and 13C-UBT were also performed within 3 days of the second endoscopy.
  
  
  RESULTS
  On the basis of biopsy-based tests, infection was eradicated in 77 patients but continued in 23. Three false negatives were observed with HpSA and two with 13C-UBT. In contrast, the number of false positives was significantly higher (P < 0.01) with HpSA than with 13C-UBT (nine vs. one), confirming the lower specificity of the former test. The overall accuracy of HpSA was 88% vs. 97% for 13C-UBT (P < 0.02).
  
  
  CONCLUSIONS
  HpSA has lower diagnostic value than 13C-UBT in the evaluation of the outcome of anti-H. pylori therapy. 13C-UBT remains the first-line diagnostic method to monitor eradication results. The use of HpSA should be reserved for those settings in which 13C-UBT is not available.
authors.affiliation: Dipartimento di Medicina Interna e Specialità Mediche, Università di Genova, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Bilardi
authors.forename: R
authors.initials: R
authors.lastname: Biagini
authors.forename: P
authors.initials: P
authors.lastname: Dulbecco
authors.forename: E
authors.initials: E
authors.lastname: Iiritano
authors.forename: C
authors.initials: C
authors.lastname: Gambaro
authors.forename: M R
authors.initials: MR
authors.lastname: Mele
authors.forename: P
authors.initials: P
authors.lastname: Borro
authors.forename: L
authors.initials: L
authors.lastname: Tessieri
authors.forename: P
authors.initials: P
authors.lastname: Zentilin
authors.forename: C
authors.initials: C
authors.lastname: Mansi
authors.forename: S
authors.initials: S
authors.lastname: Vigneri
authors.forename: V
authors.initials: V
authors.lastname: Savarino
mesh_terms: D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D000942:Antigens, Bacterial / Q000032:analysis*; D001706:Biopsy; D001944:Breath Tests / Q000379:methods; D002247:Carbon Isotopes; D004359:Drug Therapy, Combination; D005243:Feces / Q000382:microbiology*; D005260:Female; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000188:drug therapy; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D000942:Antigens, Bacterial; D002247:Carbon Isotopes