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Diagnosis

14C-urea breath test and Giemsa stain were sensitive for detecting Helicobacter pylori

ACP J Club. 1996 Jan-Feb;124:17. doi:10.7326/ACPJC-1996-124-1-017


Source Citation

Fallone CA, Mitchell A, Paterson WG. Determination of the test performance of less costly methods of Helicobacter pylori detection. Clin Invest Med. 1995 Jun;18:177-85. [PubMed ID: 7554584]


Abstract

Objective

To determine the diagnostic accuracy of the 14C-urea breath test (UBT), the hematoxylin-phloxin-saffron (HPS) stain, and the Giemsa stain in detecting Helicobacter pylori.

Design

Blinded comparison of results from the UBT, the HPS stain, and the Giemsa stain with results from a diagnostic standard, silver stain.

Setting

Endoscopy unit of a university-affiliated hospital in Canada.

Patients

50 adults (mean age 49 y, 54% women) presenting with gastrointestinal symptoms requiring endoscopy. Exclusion criteria were age < 16 years, a serious medical condition that would make gastric biopsy dangerous, or being of childbearing potential but not using adequate birth control.

Description of Tests and Diagnostic Standard

During endoscopy, 4 antral biopsy specimens were obtained from each patient for histologic staining with Steiner silver, Giemsa, and HPS stains. All histologic slides were interpreted blindly by a single pathologist who graded the severity of H. pylori infection. For the UBT, patients provided breath samples while fasting and 1, 2, 5, 10, 15, 20, 25, and 30 minutes after drinking the isotope. A positive UBT result was defined as exhaling ≥ 1.5% of the administered radioactive dose at 15 minutes. Silver staining of the biopsy specimen was used as the diagnostic standard.

Main Outcome Measures

Sensitivity, specificity, and likelihood ratios.

Main Results

The sensitivity of the UBT, HPS stain, and Giemsa stain were 95.8% (95% CI 79% to 100%), 75% (CI 53% to 90%), and 95.8% (CI 79% to 100%), respectively. Specificity was 100% (CI 87% to 100%) for all 3 methods. {The likelihood ratio for a positive UBT or Giemsa stain result approached infinity, and the likelihood ratio for a negative UBT result or Giemsa stain was 0.04.}* The UBT could also discriminate between heavily infected and moderately infected patients as defined by silver stain (P < 0.05). 23 of 24 patients had H. pylori detected in 3 of 4 biopsy specimens using either Giemsa or silver stain.

Conclusions

The 14C-urea breath test and Giemsa stain were very accurate (based on high specificity and sensitivity) in detecting Helicobacter pylori in patients presenting with gastrointestinal symptoms requiring endoscopy. The hematoxylin-phloxin-saffron stain was not as sensitive.

Source of funding: In part, Astra Pharma Inc.

For article reprint: Dr. C.A. Fallone, Division of Gastroenterology, Ross 2.28, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, Quebec H3A 1A1, Canada. FAX 514-843-1421.

*Numbers calculated from data in article.


Commentary

Noninvasive tests were as accurate as invasive tests for detecting Helicobacter pylori

With increasing media exposure, many patients know about H. pylori and now request testing. The studies by Cutler and Fallone and their colleagues expand our understanding of the diagnostic accuracy of H. pylori testing. Now we can address which tests are cost-effective and which patients should be tested.

To overcome the lack of a true "diagnostic standard," Cutler and colleagues reasonably used consistency of results among several tests to represent true infection. This group also examined a large population that included patients with gastroesophageal reflux disease and a lower pretest probability of H. pylori infection. This cohort may have produced less accurate positive and negative likelihood ratios than a more selected group of patients with peptic ulcer. Fallone and colleagues confirm that UBT and antral biopsies have essentially equivalent diagnostic accuracy.

The results from these studies indicate that CLO, Warthin-Starry (silver) stain, UBT, Giemsa stain, and tests for serum IgG have large positive likelihood ratios. Therefore, any positive H. pylori test result eliminates the need for further confirmatory testing. Because all of these tests have equivalent diagnostic accuracy in untreated patients, the method of testing should be chosen by cost and ease of use.

For patients with ulcers diagnosed by barium, H. pylori IgG testing probably will be the least expensive and easiest to obtain. For patients diagnosed at endoscopy, antral biopsies and a CLO test should be done. Only in the event of a negative CLO would the biopsy specimens be sent for special staining. Patients who do not have duodenal ulcers caused by nonsteroidal anti-inflammatory drugs, however, have a 95% to 99% pretest probability of infection. Empiric treatment in this subpopulation of patients with duodenal ulcers may be a reasonable alternative.

Current studies do not support the diagnosis or treatment of H. pylori infection in nonulcer dyspepsia (1). Future research may, however, define a subpopulation of patients with nonulcer dyspepsia for whom treatment of H. pylori infection would be advantageous. Physicians who choose to diagnose and treat on an individual basis should recognize that this currently represents the "art of medicine."

Documentation of H. pylori eradication is recommended only for patients with complicated or bleeding ulcers (1). In this important subgroup, eradication reduces the rate of recurrent bleeding ulcer (2). The rapid office-based serologic assays for H. pylori are less useful in post-treatment evaluation because of the delayed and variable IgG titer decrease. Laboratory-based serologic testing (enzyme-linked immunosorbent assay) requires that acute and post-treatment samples be run at the same time (3). UBT appears to be the ideal method to document eradication and seems to be diagnostically equivalent to, safer, and more cost-effective than the current standard of repeat endoscopy with antral biopsies. Lack of widespread availability of UBT may necessitate the continued use of endoscopy in some clinical settings.

Several additional caveats should be considered. A definitive protocol for UBT has not been established. Many different office-based serologic tests exist for H. pylori, with variable diagnostic accuracy, and may not approach the level reported by Cutler and colleagues. Additionally, all of the tests evaluated in these studies were done in untreated patients. A post-treatment group would have a lower pretest probability of infection. In this population, these same diagnostic tests would provide less information.

The rapidly expanding volume of H. pylori research will soon lead to clearer and more cost-effective guidelines. Watch for future developments.

Philip S. Schoenfeld, MD, MSEd
David J. Roberts, MD
National Naval Medical CenterBethesda, Maryland, USA


References

1. NIH Consensus Conference. Helicobacter pylori in peptic ulcer disease. JAMA. 1994;272:65-9.

2. Rokkas T, Karameris A, Mavrogeorgias A, et al. Eradication of H. pylori reduces possibility of rebleeding in peptic ulcer disease. Gastrointest Endos. 1995;41:1-4.

3. Cutler A, Schubert A, Schubert T. Role of H. pylori serology in evaluating treatment success. Dig Dis Sci. 1993;38:2262-6.