Post-treatment diagnostic accuracy of a new enzyme immunoassay to detect Helicobacter pylori in stools

Diagnosis of Helicobacter pylori infection in the elderly using an immunochromatographic assay-based stool antigen test

The diagnostic value of Helicobacter pylori stool antigen (HpSA) tests in elderly subjects remains unclear. The objective of this study was to assess the diagnostic accuracy of the immunochromatographic assay‐based HpSA test in a male elderly cohort and identify factors affecting the accuracy. Data for asymptomatic elderly male citizens (≥65 years old) who received health checkups at the Chinese PLA General Hospital between July 2007 and November 2018 were collected. The diagnostic accuracy of the HpSA test was determined using the ¹³C‐urea breath test as a reference standard. Associations between baseline comorbidities and the accuracy of the HpSA test were analyzed. In total, 316 participants were enrolled, including 193 in the pre‐treatment group (77.2 ± 7.8 years old) and 123 in the post‐treatment group (78.7 ± 8.3 years old). The accuracy (91.5%, 91.2%, and 91.9%) and specificity (97.6%, 98.7%, and 96.0%) were high in all participants, pre‐ and post‐treatment groups, respectively. However, sensitivities were only 68.7%, 65.1%, and 75.0%, respectively. In the pre‐treatment group, constipation was associated with decreased sensitivity (p = 0.039), while colorectal polyps were associated with increased sensitivity (p = 0.010). Multivariate analysis indicated that constipation and colorectal polyps are independent factors for the sensitivity of HpSA in the pre‐treatment group. The immunochromatographic assay‐based HpSA test achieved high accuracy with high specificity but suboptimal sensitivity in the elderly male cohort. Constipation and colorectal polyps were negatively and positively associated with HpSA sensitivity, respectively, in the pre‐treatment group.

Non-invasive diagnostic tests for Helicobacter pylori infection

BACKGROUND

Helicobacter pylori (H pylori) infection has been implicated in a number of malignancies and non-malignant conditions including peptic ulcers, non-ulcer dyspepsia, recurrent peptic ulcer bleeding, unexplained iron deficiency anaemia, idiopathic thrombocytopaenia purpura, and colorectal adenomas. The confirmatory diagnosis of H pylori is by endoscopic biopsy, followed by histopathological examination using haemotoxylin and eosin (H & E) stain or special stains such as Giemsa stain and Warthin-Starry stain. Special stains are more accurate than H & E stain. There is significant uncertainty about the diagnostic accuracy of non-invasive tests for diagnosis of H pylori.

OBJECTIVES

To compare the diagnostic accuracy of urea breath test, serology, and stool antigen test, used alone or in combination, for diagnosis of H pylori infection in symptomatic and asymptomatic people, so that eradication therapy for H pylori can be started.

SEARCH METHODS

We searched MEDLINE, Embase, the Science Citation Index and the National Institute for Health Research Health Technology Assessment Database on 4 March 2016. We screened references in the included studies to identify additional studies. We also conducted citation searches of relevant studies, most recently on 4 December 2016. We did not restrict studies by language or publication status, or whether data were collected prospectively or retrospectively.

SELECTION CRITERIA

We included diagnostic accuracy studies that evaluated at least one of the index tests (urea breath test using isotopes such as 13C or 14C, serology and stool antigen test) against the reference standard (histopathological examination using H & E stain, special stains or immunohistochemical stain) in people suspected of having H pylori infection.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the references to identify relevant studies and independently extracted data. We assessed the methodological quality of studies using the QUADAS-2 tool. We performed meta-analysis by using the hierarchical summary receiver operating characteristic (HSROC) model to estimate and compare SROC curves. Where appropriate, we used bivariate or univariate logistic regression models to estimate summary sensitivities and specificities.

MAIN RESULTS

We included 101 studies involving 11,003 participants, of which 5839 participants (53.1%) had H pylori infection. The prevalence of H pylori infection in the studies ranged from 15.2% to 94.7%, with a median prevalence of 53.7% (interquartile range 42.0% to 66.5%). Most of the studies (57%) included participants with dyspepsia and 53 studies excluded participants who recently had proton pump inhibitors or antibiotics.There was at least an unclear risk of bias or unclear applicability concern for each study.Of the 101 studies, 15 compared the accuracy of two index tests and two studies compared the accuracy of three index tests. Thirty-four studies (4242 participants) evaluated serology; 29 studies (2988 participants) evaluated stool antigen test; 34 studies (3139 participants) evaluated urea breath test-13C; 21 studies (1810 participants) evaluated urea breath test-14C; and two studies (127 participants) evaluated urea breath test but did not report the isotope used. The thresholds used to define test positivity and the staining techniques used for histopathological examination (reference standard) varied between studies. Due to sparse data for each threshold reported, it was not possible to identify the best threshold for each test.Using data from 99 studies in an indirect test comparison, there was statistical evidence of a difference in diagnostic accuracy between urea breath test-13C, urea breath test-14C, serology and stool antigen test (P = 0.024). The diagnostic odds ratios for urea breath test-13C, urea breath test-14C, serology, and stool antigen test were 153 (95% confidence interval (CI) 73.7 to 316), 105 (95% CI 74.0 to 150), 47.4 (95% CI 25.5 to 88.1) and 45.1 (95% CI 24.2 to 84.1). The sensitivity (95% CI) estimated at a fixed specificity of 0.90 (median from studies across the four tests), was 0.94 (95% CI 0.89 to 0.97) for urea breath test-13C, 0.92 (95% CI 0.89 to 0.94) for urea breath test-14C, 0.84 (95% CI 0.74 to 0.91) for serology, and 0.83 (95% CI 0.73 to 0.90) for stool antigen test. This implies that on average, given a specificity of 0.90 and prevalence of 53.7% (median specificity and prevalence in the studies), out of 1000 people tested for H pylori infection, there will be 46 false positives (people without H pylori infection who will be diagnosed as having H pylori infection). In this hypothetical cohort, urea breath test-13C, urea breath test-14C, serology, and stool antigen test will give 30 (95% CI 15 to 58), 42 (95% CI 30 to 58), 86 (95% CI 50 to 140), and 89 (95% CI 52 to 146) false negatives respectively (people with H pylori infection for whom the diagnosis of H pylori will be missed).Direct comparisons were based on few head-to-head studies. The ratios of diagnostic odds ratios (DORs) were 0.68 (95% CI 0.12 to 3.70; P = 0.56) for urea breath test-13C versus serology (seven studies), and 0.88 (95% CI 0.14 to 5.56; P = 0.84) for urea breath test-13C versus stool antigen test (seven studies). The 95% CIs of these estimates overlap with those of the ratios of DORs from the indirect comparison. Data were limited or unavailable for meta-analysis of other direct comparisons.

AUTHORS' CONCLUSIONS

In people without a history of gastrectomy and those who have not recently had antibiotics or proton ,pump inhibitors, urea breath tests had high diagnostic accuracy while serology and stool antigen tests were less accurate for diagnosis of Helicobacter pylori infection.This is based on an indirect test comparison (with potential for bias due to confounding), as evidence from direct comparisons was limited or unavailable. The thresholds used for these tests were highly variable and we were unable to identify specific thresholds that might be useful in clinical practice.We need further comparative studies of high methodological quality to obtain more reliable evidence of relative accuracy between the tests. Such studies should be conducted prospectively in a representative spectrum of participants and clearly reported to ensure low risk of bias. Most importantly, studies should prespecify and clearly report thresholds used, and should avoid inappropriate exclusions.

Comparison of a monoclonal with a polyclonal antibody-based enzyme immunoassay stool test in diagnosing Helicobacter pylori infection after eradication therapy

BACKGROUND

Recently, a novel Helicobacter pylori stool antigen test (Testmate pylori antigen EIA) using monoclonal antibodies against H. pylori catalase has been developed commercially. This study assessed the diagnostic usefulness of the stool antigen test compared with a polyclonal enzyme immunoassay (HpSA test) after H. pylori eradication.

METHODS

A total of 150 patients with H. pylori infection were treated by triple therapy with PPI and amoxicillin with either clarithromycin or metronidazole. H. pylori stool antigen was tested 4 and 8 weeks after eradication. The outcome of H. pylori eradication was assessed by urea breath test (UBT) 8 weeks after the end of therapy. Discordant results were followed by endoscopic examination.

RESULTS

Of 150 patients enrolled, H. pylori status was negative in 122 cases and positive in 28 cases, assessed by the 13C-UBT. On the other hand, the monoclonal stool antigen test results were negative in 126 cases and positive in 24. The polyclonal stool test results were negative in 126 cases and positive in 22. The overall sensitivity and specificity of the monoclonal stool antigen test were 91.6% (95% CI 85.9-97.3%) and 98.4% (95% CI 97.3-99.5%). The overall sensitivity and specificity of the polyclonal stool antigen test were 87.0% (95% CI 86.9-94.0%) and 97.5% (95% CI 96.1-98.9%).

CONCLUSION

The new stool antigen test using monoclonal antibody is useful for the diagnosis of H. pylori eradication 4 weeks after the end of treatment.

Faecal antigen tests in the confirmation of the effect of Helicobacter eradication therapy

BACKGROUND

The frequent occurrence of Helicobacter pylori infection requires significant health care resources after eradication therapy. Therefore the non-invasive testing methods are required to alleviate the increased work-load of health care personnel and to allow an easy control of eradication therapy. Conventionally, the effect of eradication therapy has been confirmed with 13C-urea breath test 4-6 weeks after a completed eradication.

AIM

To assess the applicability of Helicobacter pylori stool antigen tests as alternatives to the breath test in the control of the effect of eradication therapy.

METHODS

Fifty patients were diagnosed Helicobacter-positive by endoscopy and histology as well as by rapid urease test from mucosal specimen. Four weeks after an eradication therapy the patients were subjected to 13C-urea breath test as well as to faecal Helicobacter pylori antigen tests with mono- and polyclonal primary antibodies.

RESULTS

The monoclonal and polyclonal stool tests had 94% and 88% sensitivity, and 100% and 97% specificity, respectively, in the detection of Helicobacter pylori infection as compared to the 13C-urea breath test. The non-invasive test results were completely parallel in patients with various grades of mucosal atrophy or intestinal metaplasia.

CONCLUSIONS

Monoclonal faecal Helicobacter pylori antigen test is slightly superior to the polyclonal test regarding the sensitivity in the detection of stool Helicobacter antigens. Due to their sufficient sensitivity and specificity, and to their practicability and cost-effectiveness, they can be recommended for non-invasive testing of Helicobacter pylori infection as alternatives to the 13C-urea breath test.

Comparison of three stool antigen tests in confirming Helicobacter pylori eradication in adults

OBJECTIVE

Reliable and readily available non-invasive methods are needed for detection of Helicobacter pylori infection and assessment of eradication therapy. In H. pylori-positive subjects we compared three stool antigen tests (Premier Platinum HpSA, Amplified IDEIA HpStAR and ImmunoCard STAT!HpSA) with invasive tests before their eradication therapy, and with non-invasive diagnostic methods after their therapy.

MATERIAL AND METHODS

A total of 82 adults with dyspepsia (aged 24-79 years) with an H. pylori-positive rapid urease test were enrolled in the study. Before therapy, H. pylori status was also confirmed with histology, culture and serology. After eradication, success was assessed with the [13C]-urea breath test (UBT) and usually also with serology.

RESULTS

At baseline, sensitivities of these stool antigen tests were 90.2% for HpSA, 97.6% for HpStAR and 96.3% for ImmunoCard. Eradication therapy was successful in 66 patients and unsuccessful in 16. Sensitivity and specificity of the three stool antigen tests in the post-eradication setting were, respectively, 75.0% and 95.5% for HpSA, 93.8% and 98.5% for HpStAR and 87.5% and 95.5% for Immunocard.

CONCLUSIONS

The performance of all three stool antigen tests in the post-treatment setting was slightly inferior to that of the UBT test and serology, with monoclonal antibody-based tests showing better results.

Helicobacter pylori infection diagnosis in hospitalised elderly patients: the stool antigen test (HpSA) in comparison with other methods

BACKGROUND AND AIMS

Helicobacter pylori (Hp) infection prevalence increases with age. In elderly patients, who often do not collaborate and who are affected by multiple pathologies, worldwide-recognised invasive and non-invasive methods (histology and Urea Breath Test) are not easy to apply. A new test based on the detection of Hp antigens in the stool (HpSA test) is now available. The aim of our study was to evaluate the sensitivity and specificity of the HpSA test, and the interference of drugs (acid suppression, antibiotics) on test performance.

METHODS

Hp infection was detected by UBT, HpSA and histology in 122 hospitalised elderly subjects, divided into two groups according to therapy in the last month. Subjects were classified as being Hp-positive if two test results (histology and UBT) were positive, and Hp-negative if the same two test results were negative.

RESULTS

The sensitivity and specificity of the HpSA test compared with two tests (histology and UBT) were respectively 76 and 95%. In the group of patients who had not received drugs, the sensitivity and specificity of the HpSA test were respectively 76 and 96%. Instead, in the group of patients who had received pharmacological therapy, sensitivity and specificity values were respectively 67 and 100%. HpSA-positive patients had received acid suppression for 9.2 +/- 8.9 days, and false-negative patients for 27.2 +/- 9.9 days.

CONCLUSIONS

The HpSA test is simple, inexpensive, and non-invasive for Hp detection, especially in elderly subjects with no compliance. It is influenced only after several days by therapy common in the elderly.

Stool antigen test for the diagnosis of Helicobacter pylori infection: a systematic review

Our aim was to review systematically the diagnostic accuracy of the Helicobacter pylori stool antigen test. Bibliographical searches were performed in several electronic databases and abstracts from congresses up to May 2003. Eighty-nine studies (10,858 patients) evaluated the stool antigen test in untreated patients. Mean sensitivity, specificity, positive predictive value and negative predictive value were 91%, 93%, 92% and 87%, respectively. Analysis of the eight studies (1399 patients) in which pretreatment evaluation of the monoclonal stool antigen test was performed showed better (p < .001) results (96%, 97%, 96% and 97%, respectively), with a clearer distinction between positive and negative results. Thirty-nine studies (3147 patients) evaluated the stool antigen test for the confirmation of H. pylori eradication 4-8 weeks after therapy, with accuracies of 86%, 92%, 76% and 93% for mean sensitivity, specificity, positive predictive value and negative predictive value, respectively. Results were similar when a gold standard based on at least two methods was used. Relatively low accuracy was reported in some posttreatment studies with the polyclonal stool antigen test. However, excellent results (p < .001) were achieved in all the six studies evaluating the monoclonal stool antigen test 4-8 weeks posttreatment. Results evaluating the stool antigen test < 4 weeks posttreatment are contradictory. Proton-pump inhibitors seem to affect the accuracy of the stool antigen test. Sensitivity and/or specificity in patients with gastrointestinal bleeding may be suboptimal. The stool antigen test performs well in children. Finally, the stool antigen test seems to be a cost-effective method.

Are tonsils a reservoir for Helicobacter pylori infection in children?

OBJECTIVE

Helicobacter pylori (H. Pylori) has been associated with the development of gastritis, peptic ulcer and gastric cancer. Although H. pylori infects up to more than half of the world's population, to date the precise modes of transmission has not been fully understood yet. Therefore a study was planned to investigate whether the tonsils and the adenoid tissue were the reservoir or the gate for the entrance of H. pylori.

METHODS

The adenotonsillectomy specimens obtained from 50 children, between two and 10 years of age were examined for H. Pylori colonization by the CLO-test method. Before tonsillectomy, anti-H. pylori IgG antibody titers were detected by commercial enzyme immunoassay method in venous blood and H. pylori antigen enzyme immunoassay for detection of H. pylori in stool was used to define current infection status.

RESULTS

The stool antigen was positive in 25 (50%) of 50 children. Serum IgG antibody was positive in 28 (56%) patients and both tests were positive in 21 (42%) patients. H. pylori positivity was not detected in any one of the adenotonsillectomy specimens with the CLO-test method.

CONCLUSION

In this study although H. pylori was detected in stools of children, it was not detected in adenotonsillectomy specimens with CLO-test method. The results may indicate that H. pylori does not colonize in either adenoid or tonsils and that these tissues do not constitute a reservoir for H. pylori infection.

Evaluation of Helicobacter pylori stool antigen test before and after eradication therapy

BACKGROUND AND AIM

The Helicobacter pylori stool antigen (HpSA) test is useful for initial diagnosis of H. pylori infection, but there is disagreement regarding its diagnostic accuracy after eradication therapy. The aim of the present study was to evaluate the diagnostic accuracy of the HpSA test before and after eradication therapy.

METHODS

One hundred and thirty-six patients underwent upper gastrointestinal endoscopy with biopsies for the diagnosis of H. pylori infection using culture, histology and the rapid urease test. Fifty-four H. pylori-positive patients were treated with 1-week triple therapy. Six to 10 weeks after the end of therapy, the patients underwent re-endoscopy and received the same biopsy-based methods. In addition, the 13C-urea breath test was performed. The HpSA test was performed before and 6-10 weeks after the end of therapy. In 23 patients, the HpSA test was also performed at the end of therapy.

RESULTS

Before therapy, the sensitivity and specificity of the HpSA test was 98.3% (95% confidence interval (CI): 95.9-100%) and 95.0% (95% CI: 75.1-99.9%), respectively. At the end of therapy, the HpSA tests were all negative both for eradication and non-eradication patients. The sensitivity and specificity of the HpSA test after eradication therapy were 90% (95% CI: 55.5-99.7%) and 97.7% (95% CI: 93.3-100%), respectively.

CONCLUSIONS

The HpSA test is a useful method for the diagnosis of H. pylori infection before and after eradication therapy.

Review article: clinic-based testing for Helicobacter pylori infection by enzyme immunoassay of faeces, urine and saliva

Enzyme immunoassays have been used to detect Helicobacter pylori infection in human body materials such as faeces, urine and saliva. The stool antigen assay (HpSA), which uses polyclonal anti-H. pylori antibody as a capture reagent, has been widely used in the pre-treatment diagnosis of the infection in adults and children. Although the assay has the potential for monitoring eradication therapy, there are controversies over its use, especially at an early stage after treatment. The efficacy of the stool antigen assay can be modified by using monoclonal antibodies towards well characterized H. pylori faecal antigens. Two types of enzyme immunoassays (enzyme-linked immunosorbent assay [ELISA] and immunochromatography) have been used to detect antibodies to H. pylori in urine. Immunochromatography of urine is a rapid assay well suited for epidemiological studies. The salivary ELISA, used in a number of studies, has shown inconsistent results with less than optimum sensitivity and specificity. Urinary and salivary immunoassays may not distinguish between past and present infections, thus limiting their potential to monitor eradication therapy.

Evaluation of two stool antigen tests for the detection of Helicobacter pylori infection in the Chinese population

BACKGROUND AND AIM

The stool antigen test, the HpSA test, has been validated mainly in Western countries, but not properly in the Chinese population. Recently, another stool antigen test, the Apollo test, was developed, but its accuracy has rarely been validated. The aim of this study is to compare the accuracy of these two tests in the diagnosis of Helicobacter pylori infection in the Chinese population.

METHODS

Consecutive dyspeptic patients referred for upper endoscopy were recruited. During endoscopy, biopsies were taken for the rapid urease test and histological examination as the gold standard. Stool specimens were collected and used for the HpSA and Apollo tests.

RESULTS

Overall, 86 patients (39 males and 47 females, with a mean age of 55.8 years) were recruited. Helicobacter pylori infection was present in 44 (51%) patients as determined by the gold standard. The sensitivity, specificity and accuracy were 86.4, 100, and 93.0%, respectively, for the HpSA, and 90.9, 97.6, and 94.2%, respectively, for the Apollo test when cases with equivocal results were considered as positive. In addition, agreement was achieved in 81 (94.2%) cases between the two tests, with a Kappa value of 0.887.

CONCLUSION

Both the HpSA and Apollo tests achieve acceptable sensitivity and excellent specificity, with accuracies of over 90% for the detection of H. pylori infection in the Chinese population.

Optimal serological tests for the detection of Helicobacter pylori infection in the Chinese population

BACKGROUND

Numerous serological tests for the detection of Helicobacter pylori infection have been developed. However, many perform poorly when evaluated in the Chinese population.

AIM

To search for optimal serological tests for the detection of H. pylori infection in Chinese patients.

METHODS

Consecutive dyspeptic patients referred for upper endoscopy were recruited. During endoscopy, gastric biopsies were taken for the CLOtest and histological examination. Patients were then given a 13C-urea breath test. Sera were used to test for H. pylori infection, employing three commercial enzyme-linked immunosorbent assay kits (pylori DTect, HP IgG and GAP IgG). Results were compared with the gold standard defined by the CLOtest, histology and 13C-urea breath test.

RESULTS

Among the 142 patients (47 male, 95 female; mean age, 49 years) recruited, 81 (57%) were H. pylori-positive, 57 (40%) were H. pylori-negative and four (3%) were defined to be indeterminate. Using a self-defined cut-off value after calculation, the best accuracies for the pylori DTect, HP IgG and GAP IgG tests were 97%, 91% and 80%, respectively.

CONCLUSIONS

The pylori DTect test is an optimal serological test for the detection of H. pylori infection in Hong Kong Chinese patients. The HP IgG test may be used as an alternative.

Helicobacter pylori infection: treatment

Current standard treatment regimens for Helicobacter pylori infection provide eradication rates 80 to 90%. These rates have been achieved with a variety of 1-week triple therapies using two antibiotics and an acid suppressant. Antibiotic resistance, which may develop during failed treatment, is becoming increasingly common and has led to studies of new regimens for primary therapy, and new strategies for salvage of failed therapy. Other regimens have been designed and tested with the aim of decreasing the cost of initial therapy or to improve compliance, but abbreviated regimens have high incidence of failure and may add to the problem of resistance. Increasing attention has been paid to the need for, and timing of, the determination of antibiotic resistance of H. pylori isolates either at the time of initial diagnosis or after treatment failure. New, simpler, and noninvasive methods are offered for follow-up to determine if eradication has been successful. Treatment regimens should be chosen based on local drug susceptibility patterns and the availability of approved therapeutic agents in each country. Established indications for testing for H. pylori and administering therapy include active or inactive peptic ulcer disease, mucosa-associated lymphoid tissue (MALT) lymphoma, as well as hyperplastic polyps, hyperplastic gastropathy, postendoscopic resection for gastric malignancy, and acute H. pylori gastritis. It is now largely accepted that noninvestigated dyspepsia is an indication for testing for and treating H. pylori, but that dyspeptic symptoms shown not to be associated with ulcer (nonulcer dyspepsia) do not now provide an indication for testing. Controversial or unresolved indications for testing and treating include planned use of chronic antisecretory therapy, planned use of nonsteroidal anti-inflammatory drugs, and use as a general approach to the prevention of gastric cancer.