This article is the summary/review of the following article:

Best, L. M., Takwoingi, Y., Siddique, S., Selladurai, A., Gandhi, A., Low. B., ... Gurusamy, K. S. (2018). Non-invasive diagnostic tests for Helicobacter pylori infection (review). Cochrane Database of Systematic Reviews, 3, CD012080. doi:10.1002/14651858.CD012080.pub2

Background

Helicobacter pylori (H. pylori) is a gram-negative spiral bacterium (NCBI, 2014), which is commonly found in the stomach, among other areas. H. pylori is a major cause of morbidity and mortality worldwide and has been linked to a number of malignancies including gastric cancer, premalignant lesions of the stomach, gastric lymphoma, pancreatic cancer, colorectal cancer, and laryngeal cancer. It is also associated with a number of nonmalignant conditions including peptic ulcers, unexplained iron-deficiency anemia, and colorectal adenomas. The prevalence of the bacterium tends to increase with age and is associated with poorer socioeconomic settings (Peleteiro, Bastos, Ferro, & Lunet, 2014).

There are three main diagnostic tests used to identify the presence of H. pylori in patients; namely, the urea breath tests, a serum blood test, and a stool antigen test. The urea breath test involves the collection of breath samples from patients and is based on the ability of H. pylori to convert urea to ammonia and carbon dioxide. There are two types of urea breath tests used on the basis of two different carbon isotypes, ¹³C and ¹⁴C. Serology can be used to identify the existence of circulating antibodies to H. pylori, specifically an enzyme-linked immunosorbent assay (ELISA) test specific to H. pylori antibodies is used. In a stool antigen test, monoclonal and polyclonal antibodies are used to detect the presence of the H. pylori antigen in the stools of a patient. Biopsy is currently the most accurate test available; however, it is known to cause physical discomfort to patients and is associated with an increased risk of harm, which is why these noninvasive tests would be preferable if they are shown to be as accurate as biopsy.

The testing, and subsequent eradication, of H. pylori has been recommended in populations at high risk of gastric cancer, unexplained iron deficiency, and idiopathic thrombocytopenia purpura, and in some cases adults and young patients with dyspepsia. The initial treatment of cases of H. pylori infection typically involves the administration of three different medications-a proton pump inhibitor, clarithromycin, and amoxicillin or metronidazole: a triple therapy. Adverse events associated with this drug regimen include diarrhea, nausea, headache, abdominal pain, constipation, dizziness, bloating, myalgias, skin rash, and taste disturbance (Ye et al., 2014).

Objective(s)

The primary objective of this review was to compare the accuracy of three different diagnostic or index tests (the urea breath test, serology, and stool antigen test) used alone or in combination, for the diagnosis of H. pylori infection.

Intervention/Methods

The review included studies that evaluated the accuracy of the three previously identified types of diagnostic tests. Both prospective and retrospective data collection methods were considered. Case-control studies were excluded.

Participants included adults and children who were symptomatic or asymptomatic and in whom a diagnosis of H. pylori was required for treatment purposes. Studies that included only patients with upper gastrointestinal bleeding were excluded.

Results

There were 101 studies included in this review, representing a total of 11,003 participants, 5,839 (53%) of whom had H. pylori infection. All the studies compared the results from one of the three index tests with a diagnosis provided by endoscopic biopsy. Of the 101 studies, 34 evaluated serology, 29 evaluated stool antigen tests, and 57 evaluated urea breath tests. The thresholds used to define test positivity varied between studies, and because of the lack of data, the review authors reported that it was not possible to determine the best threshold for each test.

The review authors reported that data from 99 studies identified statistical evidence of a difference in diagnostic accuracy between the urea breath test ¹³C and ¹⁴C, serology, and stool antigen test. The urea breath test was found to be more accurate than serology and stool antigen tests. These results were based on indirect test comparisons, as evidence from direct comparison was limited. In studies that compared the urea breath test and serology or stool antigen tests in the same participants, the results were uncertain and the accuracy of the different combinations could not be determined. The review authors cautioned that in all but one study, the studies were of poor methodological quality, which means the results of the study should not be considered definitive.

Conclusions

H. pylori is associated with a number of malignant and nonmalignant conditions and is a major cause of morbidity and mortality globally. Therefore, the testing and subsequent eradication of H. pylori has been recommended in high-risk populations. This review reported that for patients with no history of gastrectomy and those who have not recently had antibiotics or proton pump inhibitors, the urea breath test may have higher diagnostic accuracy in detecting H. pylori infection than serology and stool antigen tests.

Implications for Practice

The most accurate method for the diagnosis of H. pylori infection is an endoscopic biopsy. However, this method is invasive and more costly than the index tests considered in this review. Of the noninvasive tests available, the urea breath test appears to be the most accurate based on current evidence; however, until better quality studies are conducted, we cannot be sure. It is hoped that these studies will be conducted in the near future to allow for recommendation of these noninvasive tests in relevant patient populations.

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