Helicobacter pylori Testing in Subjects with Dyspepsia
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Helicobacter pylori Testing in Subjects with Dyspepsia.pdf)
When I was a medical student I would be failed if I said that peptic ulcer disease was an infectious disease. Through the period of my career, the single biggest change in the way in which we think about medical disease, in my view, has been in the area of peptic ulcer disease. It is now clear that an essential component in the chain of events that lead to peptic ulcer disease, as well as a proportion of subjects with non ulcer dyspepsia, is infection with the gram - negative spiral bacterium, Helicobacter pylori (H. pylori). The organism colonises the gastric mucosal surface and is a risk factor for carcinoma of the stomach, as well as lymphoma of the gastric mucosa. This recognition has changed the diagnostic and therapeutic approach to dyspepsia.
Health economists have identified the cost effectivity of eradicating Helicobacter infection. For example, the County of Suffolk in the United Kingdom has analysed a population of 650,000 people serviced by 395 general practitioners where the budget for ulcer therapy is £4M per year. They developed a screening programme based on detection of serum antibody in subjects with dyspepsia, and demonstrated a 55% reduction in drug therapy. In the United States, recent studies have shown that for every screening test done in a dyspeptic patient there is a minimum saving of US$125. Current eradication antibiotic therapy over one week, regularly claims an eradication rate of >90%. This contrasts with an 80%, 1 year recurrence rate of duodenal ulcer healed by acid suppression alone.
Diagnostic Strategies
How then, should we be approaching diagnosis of Helicobacter pylori in patients presenting with dyspepsia? This is an evolving and somewhat controversial area, but there is a consolidating view to support the non-invasive diagnosis of Helicobacter pylori in patients under the age of 45 years. This view is supported by guidelines developed by an international group of experts meeting in Holland, known as the 'Maastrecht Guidelines'. Endoscopy is recommended as a primary investigation in subjects older than 45 years, to avoid missing detection of early carcinoma of the stomach. A number of studies have confirmed that cost effective non-invasive diagnosis in subjects with dyspepsia under the age of 45 years, can reduce the overall endoscopy rate by 30-50%. The advantage of non-invasive diagnosis is that it is unaffected by focal disease and may have greater sensitivity in patients with 'low infection dose' disease that can be missed at endoscopy.
Non-Invasive Tests
Two non-invasive methods are available. The first is the urea-breath test, and the second is detection of circulating IgG H. pylori antibodies. The breath test has a high sensitivity and specificity but has a number of practical difficulties, including a requirement to cease current medication for several days, a need for a second visit, a potential problem of oral contamination with urease-producing bacteria and a problem of unrecognised use of antibiotics (which suppress H. pylori growth). However, currently it is the only available sensitive technique to determine effective eradication of Helicobacter pylori without using endoscopy. The role for the urea breath test is to validate eradication of H. pylori several weeks after completion of therapy. Detection of serum antibody has a sensitivity and specificity of about 90%, but is an insensitive method for detecting post therapy eradication. It is cheap and is unaffected by concurrent acid suppression therapy. However, a serum antibody test can remain positive for many months after successful eradication therapy. Detection of circulating IgG anti-H. pylori antibody is the recommended way of diagnosing H. pylori infection (Figure 1).
The accompanying Flow Chart (Figure 1) summarises current views on management of subjects with dyspepsia in whom non steroidal anti-inflammatory drugs are not being ingested, and who have not had H. pylori eradication therapy.
Figure 1
Legend
Positive Serological Test Negative Serological Test
References
- RAUWS EAJ AND TYTGAT GNJ. Cure of duodenal ulcer associated with eradication of Helicobacter pylori. Lancet 1990; 335: 1233-1235
- AXON R. Duodenal ulcer: the villian unmasked? Eradicating Helicobacter pylori will cure most patients. BMJ 1991; 302: 919-921
- MARSHALL BJ, PLANKEY MW, HOFFMAN SR, et al. A 20-minute breath test for Helicobacter pylori. Am J Gastroenterol 1991; 86: 438-445.
- ATHERTON JC, HYMEN-TAYLOR P, HAWKEY CJ et al. Direct comparison of 13C and low dose 14C as isotopic markers in the urea breath test. Gut 1992; 33 (suppl 2): S55.
- LIN SK, LAMBERT JR, SCHEMBRI M et al. A comparism of diagnostic tests to determine Helicobacter pylori infection. J. Gastro & Hepatology 1992; 7: 203-209
- BELL GD, POWELL KU. Helicobacter pylori eradication. The Practitioner 1993; 237: 306-310
- FORBES CM, GLASER ME, CULLEN DJE et al. Duodenal ulcer treated with H.pylori eradication: seven year follow-up. Lancet 343, 258-260
- MEGRAUD F. Epidemiology of H.pylori infection. In: Rathbone BJ, Heatley BV (Eds). Helicobacter pylori and gastoduodenal disease. 2nd Edition. Blackwell Scientific Publications, 1993: 107-123
- MARSHALL BJ. Helicobacter pylori. Am J Gastroenterol. 1994; 89 (suppl): S116-S128
- National Institutes of Health, Consensus Development Conference Statement, Helicobacter pylori in peptic ulcer disease, Feb 7-9, 1994.
- ZOTTI R, MORCOM J, McCARTHY PJ AND NARIELVALA FM. Evaluation of the 1uCi 14C-urea breath test versus the CLO test for the detection of Helicobacter pylori. Am J Gastroenterol 1994; 89: 1027-1031
- LEUNG VKS and SUNG JJY. Diagnosis of Helicobacter pylori infection. JIFCC 1996; 8: 161-166.
Written by: Professor Robert Clancy, Immunology HAPS
Written: December 1998
Last Reviewed: 10.5.2001
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