Sandra Yin

November 01, 2011

November 1, 2011 (National Harbor/Washington, DC) — Polymerase chain reaction (PCR) sensed more than twice the number of cases of Helicobacter pylori as immunohistochemistry (IHC), according to the results of a study presented here at the American College of Gastroenterology (ACG) 2011 Annual Scientific Meeting and Postgraduate Course.

The researchers wanted a better way to diagnose H pylori and functional dyspepsia. They had no explanation for a large number of patients' abdominal symptoms and wondered whether they were missing something, said lead author Rudra Rai, MD, FACG, medical director of the Gastro Center of Maryland and assistant professor of medicine at Johns Hopkins University School of Medicine in Baltimore.

In a prospective study of 325 adults with chronic gastroduodenal symptoms, Dr. Rai and colleagues found that IHC was positive for H pylori in 8% of cases, whereas PCR was positive in 20% — more than double that of IHC. PCR captured all patients who tested positive on IHC, with no false negatives.

"If we believe these results, the majority of these H pylori patients — 59% — would have been missed under immunohistochemistry, would have likely been diagnosed with functional dyspepsia,...and would potentially have gone through a different set of medications and additional diagnostic tests," Dr. Rai pointed out.

Perhaps the most surprising thing about the findings is how many people had undiagnosed H pylori, Dr. Rai told Medscape Medical News. "Almost 12% of the people who come in with stomach pain have this low level of bacteria," he said. "The sheer number was fairly stunning."

The prospective study involved patients who underwent upper endoscopic exams. The endoscopist took biopsies from the gastric antrum and fundus; duplicate samples for were sent simultaneously to undergo IHC and a commercially available multiplex PCR (TZAM Diagnostics).

PCR doubled the number of people who would benefit from treatment, Dr. Rai told Medscape Medical News. The diagnosis of H pylori changes lives. Patients can get off proton pump inhibitors; these suppress stomach acid, providing partial relief but not taking care of the source of the problem, he said. Indeed, after treatment for H pylori, 84% of patients saw their symptoms improve, said Dr. Rai, and the majority were able to discontinue proton pump inhibitors after 2 or 3 months.

Overall, only 40% of H  pylori detected with PCR was detected with IHC. In males, only half of the 27% of PCR-detected H pylori was detected with IHC, and only about one third of the 16% of females was. Only one sixth of PCR-detected H pylori in whites was detected with IHC, whereas 63% was detected in blacks.

Dr. Rai said he encourages community gastroenterologists to reproduce the results for themselves. "I think they'll start to see benefits — probably within the first few months of using this test," he said. The US Food and Drug Administration has approved the test as a backup to IHC.

H pylori can be challenging. Many patients present with dyspeptic symptoms; physicians often don't find a specific cause and classify them as nonulcer dyspepsia, said Jonathan Leighton, MD, FACG, a gastroenterologist from the Mayo Clinic in Scottsdale, Arizona, and chair of the ACG Educational Affairs Committee. "If in fact some of those patients are infected with H pylori, it's important to know because, obviously, the treatments are very different," he said.

If it's true that more patients with H pylori are detected with PCR, gastroenterologists can use it to identify patients with dyspepsia who really do have H pylori, Dr. Leighton said. However, he warned about the false-positive results that PCR might produce.

PCR "can detect genetic material," he said. "We have to make sure the positive predictive value is very good and that we don't wind up treating patients unnecessarily."

The good news is that PCR should be cost effective, he said.

It will be important to look at outcomes in the group of patients who improve, Dr. Leighton said, to make sure there's no placebo effect. Larger prospective studies are needed to detect that.

Dr. Rai reports financial relationships with BMS, Genentech, Gilead, and Onyx, but none related to this study. Dr. Leighton reports financial relationships with Given Imaging, Intromedic, Procter and Gamble, Abbott, Bristol-Myers Squibb, Capsovision, Centocor Ortho Biotech Inc., Exagen, Given Imaging, and Schering Plough.

American College of Gastroenterology (ACG) 2011 Annual Scientific Meeting and Postgraduate Course. Abstract 2. Presented October 31, 2011.


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