title: Serologic screening before endoscopy: the value of Helicobacter pylori serology, serum recognition of the CagA and VacA proteins, and serum pepsinogen I.
abstract: BACKGROUND
  We wanted to assess the diagnostic value of pre-endoscopy screening by Helicobacter pylori serology, serum recognition of the CagA and VacA proteins, and serum pepsinogen I levels (sPGI) in patients up to 55 years of age with uncomplicated simple dyspepsia.
  
  
  METHODS
  Consecutive dyspeptic patients referred for open-access endoscopy, excluding patients with alarm symptoms, recent intake of acid suppressants, or ingestion of non-steroidal anti-inflammatory drugs. H. pylori status was determined by histology and urease testing. H. pylori serologic status was determined with the enzyme-linked immunosorbent assay (ELISA) and Western blotting, serum recognition of CagA and VacA with Western blot, and sPGI levels by radioimmunoassay.
  
  
  RESULTS
  One hundred and fifteen patients were studied (mean age, 40 years: range, 20-55 years), of whom 58 were H. pylori-positive in biopsy-based tests. Twenty-one patients (18%) had significant gastroduodenal lesions (erosions, ulcers, or cancer). The sensitivity (specificity) of the ELISA (optimized) and Western blot in determining H. pylori status was 94.8% (89.5%) and 100% (96.4%), respectively. Screening strategies based on the ELISA or Western blot for determining H. pylori serologic status would have detected 95% or 100% of significant lesions, respectively, and each 'saved' 47% of endoscopies for simple dyspepsia. Serum recognition of the CagA protein would have detected 95% of significant lesions and 'saved' 55% of endoscopies, whereas recognition of the VacA protein would have detected only 81% of the lesions. Screening by H. pylori serology plus a 'low' (<55 ng/ml) or 'high' sPGI (>125 ng/ml) would detect only 57% of significant lesions, although the only case of cancer was included in the hypopepsinogenaemic subgroup of just 11 patients.
  
  
  CONCLUSIONS
  In patients with uncomplicated, simple dyspepsia up to 55 years of age, screening by H. pylori serology identified 95%-100% of patients with significant gastroduodenal lesions while potentially saving 46.9% of endoscopies. Serum recognition of the CagA protein identified 95% of lesions and would have saved an additional number of endoscopies (7.9%) compared with basic serology. Measurement of sPGI was of limited diagnostic value.
authors.affiliation: Pathology Dept, St. James's University Hospital, Leeds, UK.
authors.forename: K
authors.initials: K
authors.lastname: Bodger
authors.forename: J I
authors.initials: JI
authors.lastname: Wyatt
authors.forename: R V
authors.initials: RV
authors.lastname: Heatley
mesh_terms: D000328:Adult; D000942:Antigens, Bacterial / Q000097:blood*; D001426:Bacterial Proteins / Q000097:blood; D015153:Blotting, Western; D004415:Dyspepsia / Q000175:diagnosis* / Q000382:microbiology; D004724:Endoscopy; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D016481:Helicobacter Infections / Q000097:blood / Q000175:diagnosis* / Q000276:immunology*; D016480:Helicobacter pylori / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020116:Pepsinogen A / Q000097:blood*; D011863:Radioimmunoassay; D018709:Statistics, Nonparametric
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori; D020116:Pepsinogen A