Best method of detecting prior Helicobacter pylori infection

Utilization of an Automated Latex Agglutination Turbidity Assay for Assessing Gastric Mucosal Alteration during Helicobacter pylori Infection

Background/Aims

: A latex agglutination turbidity (LA) assay to test for serum antibodies has been approved in Japan and Korea for mass screening of Helicobacter pylori infection. In this study, we evaluated the LA assay for diagnosing H. pylori infection and predicting gastric mucosal changes in a Mongolian population.

Methods

: In total, 484 individuals were classified into H. pylori-positive (n=356) and H. pylori-negative (n=128) groups, as determined by histology and H. pylori culture.

Results

: The best cutoff, sensitivity, and specificity values for the LA assay were 18.35 U/mL, 74.2%, and 65.6%, respectively. The LA values in the atrophic gastritis group were statistically higher than those in the other groups (healthy, chronic gastritis, intestinal metaplasia, and gastric cancer, p<0.0001). The cutoff value to distinguish the atrophic gastritis group from the other four groups was 32.0 U/mL, and its area under the curve was 0.673, which was the highest among the E-plate, pepsinogen (PG) I, PG II, and PG I/II ratio tests in our data. The odds ratios for atrophic gastritis determined by the LA assay and PG I test in multiple logistic regression were 2.5 and 1.9, respectively, which were significantly higher than for the other tests.

Conclusions

: The LA assay can determine the risk of atrophic gastritis, which in turn is a considerable risk factor for gastric cancer. We propose using this assay in combination with the PG I/II ratio to avoid missing gastric cancer patients who have a low LA value (less than 32.0 U/mL).

The relative and attributable risks of cardia and non-cardia gastric cancer associated with Helicobacter pylori infection in China: a case-cohort study

BACKGROUND

Helicobacter pylori infection is a major cause of non-cardia gastric cancer (NCGC), but its causal role in cardia gastric cancer (CGC) is unclear. Moreover, the reported magnitude of association with NCGC varies considerably, leading to uncertainty about population-based H pylori screening and eradication strategies in high-risk settings, particularly in China, where approximately half of all global gastric cancer cases occur. Our aim was to assess the associations of H pylori infection, both overall and for individual infection biomarkers, with the risks of NCGC and CGC in Chinese adults.

METHODS

A case-cohort study was done in adults from the prospective China Kadoorie Biobank study, aged 30-79 years from ten areas in China (Qingdao, Haikou, Harbin, Suzhou, Liuzhou, Henan, Sichuan, Hunan, Gansu, and Zhejiang), and included 500 incident NCGC cases, 437 incident CGC cases, and 500 subcohort participants who were cancer-free and alive within the first two years since enrolment in 2004-08. H pylori biomarkers were measured in stored baseline plasma samples using a sensitive immunoblot assay (HelicoBlot 2.1), with adapted criteria to define H pylori seropositivity. Cox regression was used to estimate adjusted hazard ratios (HRs) for NCGC and CGC associated with H pylori infection. These values were used to estimate the number of gastric cancer cases attributable to H pylori infection in China.

FINDINGS

Of the 512 715 adults enrolled in the China Kadoorie Biobank between June, 2004, and July, 2008, 500 incident NCGC cases, 437 incident CGC cases, and 500 subcohort participants were selected for analysis. The seroprevalence of H pylori was 94·4% (95% CI 92·4-96·4) in NGCG, 92·2% (89·7-94·7) in CGC, and 75·6% (71·8-79·4) in subcohort participants. H pylori infection was associated with adjusted HRs of 5·94 (95% CI 3·25-10·86) for NCGC and 3·06 (1·54-6·10) for CGC. Among the seven individual infection biomarkers, cytotoxin-associated antigen had the highest HRs for both NCGC (HR 4·41, 95% CI 2·60-7·50) and CGC (2·94, 1·53-5·68). In this population, 78·5% of NCGC and 62·1% of CGC cases could be attributable to H pylori infection. H pylori infection accounted for an estimated 339 955 cases of gastric cancer in China in 2018.

INTERPRETATION

Among Chinese adults, H pylori infection is common and is the cause of large numbers of gastric cancer cases. Population-based mass screening and the eradication of H pylori should be considered to reduce the burden of gastric cancer in high-risk settings.

FUNDING

Cancer Research UK, Wellcome Trust, UK Medical Research Council, British Heart Foundation, Kadoorie Charitable Foundation, National Key Research and Development Program of China, and National Natural Science Foundation of China.

Helicobacter pylori seroprevalence in six different ethnic groups living in Amsterdam: The HELIUS study

BACKGROUND

Helicobacter pylori prevalence varies greatly worldwide. We explored the prevalence of H. pylori and CagA seropositivity among adults aged 18-44 years living in the Netherlands by ethnicity and migration status (first vs second generation).

MATERIALS AND METHODS

Participants from six different ethnic groups were selected from the population-based multi-ethnic HELIUS study in Amsterdam, the Netherlands. Serum samples were tested for H. pylori antigens using a validated Luminex-based multiplex serology assay. Prevalence ratios were estimated using Poisson regression analysis.

RESULTS

A total of 4683 participants aged 18-44 years were randomly selected based on sex, ethnicity, and age. H. pylori seroprevalence was highest in the Ghanaian group (84%), followed by Moroccan (81%), Turkish (66%), African Surinamese (51%), South-Asian Surinamese (48%), and Dutch (17%) participants. All ethnic minority groups had a significantly higher risk of being H. pylori seropositive compared to the Dutch group. This association was strongest among participants born outside the Netherlands (first generation), but was still significant and apparent among second-generation participants. Among first-generation participants, all groups, except the Moroccans, had a significantly higher proportion of individuals with a cagA + H. pylori strain compared to the Dutch participants.

CONCLUSION

Helicobacter pylori seroprevalence among first-generation migrants is high in the Netherlands and remains elevated among second-generation migrants (ie, those born in the Netherlands). High exposure to H. pylori, and especially to the more virulent cagA+ strain, highlights the need for tailored prevention of gastric diseases (notably peptic ulcers and cancers) among migrants.

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.

Effectiveness of Gastric Cancer Screening on Gastric Cancer Incidence and Mortality in a Community-Based Prospective Cohort

Purpose

This study was performed to investigate the effectiveness of gastric cancer (GC) screening methods in a community-based prospective cohort of the Korean Multi-center Cancer Cohort (KMCC) with over a 10-year follow-up.

Materials and Methods

A total 10,909 and 4,773 subjects from the KMCC with information on gastroendoscopy (GE) and upper gastrointestinal series (UGIS) were included in this study. Cox proportional hazard model adjusted for age, sex, Helicobacter pylori infection, cigarette smoking, and alcohol drinking was used to estimate the hazard ratios (HRs) and 95% confidence interval (CI).

Results

The GE screened subjects had almost half the risk of GC-specific death than that of unscreened subjects (HR, 0.58; 95% CI, 0.36 to 0.94). Among the GC patients, GE screenees had a 2.24-fold higher survival rate than that of the non-screenees (95% CI, 1.61 to 3.11). In particular, GE screenees who underwent two or more screening episodes had a higher survival rate than that of the non-screenees (HR, 13.11; 95% CI, 7.38 to 23.30). The effectiveness of GE screening on reduced GC mortality and increased survival rate of GC patients was better in elderly subjects (≥ 65 years old) (HR, 0.47; 95% CI, 0.24 to 0.95 and HR, 8.84; 95% CI, 3.63 to 21.57, respectively) than that in younger subjects (< 65 years old) (HR, 0.66; 95% CI, 0.34 to 1.29 and HR, 1.83; 95% CI, 1.24 to 2.68, respectively). In contrast, UGIS screening had no significant relation to GC mortality and survival.

Conclusion

The findings of this study suggest that a decreased GC-specific mortality and improved survival rate in GC patients can be achieved through GE screening.

Association between Helicobacter pylori infection and pancreatic cancer development: a meta-analysis

BACKGROUND

Pancreatic cancer is one of the most troublesome malignancies with dismal prognosis. H. pylori has been recognized as a type I carcinogen. Several studies have evaluated the association between H. pylori infection and pancreatic cancer development, however, the conclusions are inconsistent.

METHODS

Literature search was carried out in PubMed, EMBASE, Cochrane Library and CNKI databases to identify eligible researches. We performed overall meta-analysis of all studies included and subgroup analysis based on regional distribution. Quality of the studies (assessed by Newcastle-Ottawa quality assessment scale for case-control studies) and CagA+ strains of H. pylori were taken into consideration, and we conducted additional analyses including high-quality researches and those concerning CagA+ H. pylori respectively.

RESULTS

9 studies involving 3033 subjects (1083 pancreatic cancer cases, 1950 controls) were included. Summary OR and 95%CI of the overall meta-analysis of all included studies were 1.47 and 1.22-1.77, pooled data of the 4 high-quality studies were OR 1.28, 95%CI 1.01-1.63. OR of the 5 studies examined CagA+ strains was 1.42, corresponding 95%CI was 0.79 to 2.57. Summary estimates of subgroup analysis based on regional distribution are as follows, Europe group: OR 1.56, 95%CI 1.15-2.10; East Asia group: OR 2.01, 95%CI 1.33-3.02; North America group: OR 1.17, 95%CI 0.87-1.58. There was not obvious heterogeneity across the 9 studies. No publication bias was detected.

CONCLUSION

H. pylori infection is significantly, albeit weakly, associated with pancreatic cancer development. The association is prominent in Europe and East Asia, but not in North America. CagA+ H. pylori strains appear not to be associated with pancreatic cancer. However, more studies, especially prospective studies, are needed to validate our results.

Factors contributing to the underestimation of Helicobacter pylori-associated gastric cancer risk in a high-prevalence population

OBJECTIVE

This study aimed to identify sources of underestimation of the association between Helicobacter pylori infection and non-cardia gastric cancer, in a high-risk European population.

METHODS

Non-cardia gastric cancer patients (n = 420) recruited in two major hospitals in North of Portugal and population controls (n = 1,389) were evaluated. Whole-cell IgG antibodies against H. pylori were quantified by ELISA and Western Blot testing was conducted in a subsample (272 cases and 186 controls) allowing for the detection of current infection marker and CagA. Sex- and age-adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were computed.

RESULTS

When assessing infection by ELISA, the OR for its association with gastric cancer decreases and reverts as IgG titers increased, from 1.96 (95% CI: 1.09-3.54) for borderline positive results (16.0-21.9 RU/ml) to 0.52 (95% CI: 0.36-0.74) for the highest IgG levels (> or = 102.0 RU/ml). The same pattern was observed across strata of age and blood collection timing with stronger associations among younger subjects and those providing blood samples earlier after diagnosis. The presence of CagA (Western Blot) was associated with an increased risk of gastric cancer (OR = 11.32; 95% CI: 5.64-22.73).

CONCLUSION

The use of methods with low sensitivity to detect past infection leads to a substantial underestimation of gastric cancer risk in high-prevalence settings.

Prevalence and time trend of intestinal metaplasia in Hong Kong

BACKGROUND AND METHODS

Upper endoscopy records from 1998 to 2003 were reviewed. The demographic data, endoscopic diagnosis, results of rapid urease test and the absence or presence of intestinal metaplasia (IM) in histology were reviewed, to evaluate the prevalence of IM and Helicobacter pylori (Hp) infection over time in Hong Kong.

RESULTS

Among 1805 endoscopies performed, 1751 had both rapid urease test and histology available. A significant drop in the prevalence of duodenal ulcers from 17.9% in 1998 to 9.8% in 2003 was found (P = 0.015). Prevalence of IM was 13.9%, 5.9% and 9.4% in Hp positive, Hp negative and overall respectively (P < 0.05). The prevalence of IM increased with age, and the patterns were similar amongst subjects in 1998-2000 and those in 2001-2003. There was progressive decrease in Hp prevalence from 58% in 1998 to 40% in 2001 (P = 0.014), but no further decrease was seen in 2002-3. There was no corresponding decrease in IM prevalence. Instead IM prevalence in 2002-2003 was significantly higher than the prevalence in previous few years (P = 0.04).

CONCLUSION

The prevalence of IM did not change in the period from 1998 to 2003 despite a drop in the prevalence of Hp infection since 1994.

Evaluation of a commercial immunoblot, Helicoblot 2.1, for diagnosis of Helicobacter pylori infection

The best method to diagnose Helicobacter pylori infection in different clinical situations is controversial. The aim of the study was to assess the performance of a commercial immunoblot, Helicoblot 2.1. The study comprised 215 patients, who were grouped according to the presence of H. pylori infection (assessed by two gastroscopies including histology with a median interval of 7.1 years, enzyme immunoassay [EIA]-based serology, and history of previous H. pylori infections and eradication therapies) into four categories: no H. pylori infection ever, previous infection, ongoing infection, and EIA seropositivity as the only marker of a possible previous infection. The sensitivity of Helicoblot 2.1 to show an ongoing or previous H. pylori infection was 100% and 92%, respectively. Helicoblot 2.1 was negative in only 80% of individuals with no evidence of present or previous infection but in 96% of patients 50 years of age or younger. The current infection marker of the immunoblot was positive in 49% of patients with successful H. pylori eradication therapy. After successful eradication therapy, Helicoblot 2.1 sustained positive results in 87% of patients, and CagA positivity was detected in 87% of patients with follow-up samples for more than 10 years after therapy. Helicoblot 2.1 is a sensitive and, among patients of ages 50 years or younger, a specific test in the primary diagnosis of H. pylori infection. However, it does not discriminate between past and current infections. It can be used in epidemiological studies assessing the role of H. pylori in different late sequelae.

Diagnosis of Helicobacter pylori: invasive and non-invasive tests

Helicobacter pylori infection can be diagnosed by invasive techniques requiring endoscopy and biopsy (e.g. histological examination, culture and rapid urease test) and by non-invasive techniques, such as serology, the urea breath test, urine/blood or detection of H. pylori antigen in stool specimen. Some non-invasive tests, such as the urea breath test and the stool antigen test, detect active infection: these are called 'active tests'. Non-invasive tests (e.g. serology, urine, near-patient tests) are markers of exposure to H. pylori but do not indicate if active infection is ongoing; these are 'passive tests'. Non-invasive test-and-treat strategies are widely recommended in the primary care setting. The choice of appropriate test depends on the pre-test probability of infection, the characteristics of the test being used and its cost-effectiveness.

Ex vivo visualization of Helicobacter pylori using an endocytoscopic probe

Observation of microorganisms by endoscopy has been technically difficult. In this study, we tried to visualize bacteria during endoscopic examination to provide a powerful tool for a diagnosis of gastrointestinal infection. We observed the bacterium Helicobacter pylori, cultured ex vivo, using a novel ultra-high "magnified endoscopy" system ("endocytoscopy" prototype, Olympus Medical Systems). Cultures were prepared from gastric mucus obtained from three gastric ulcer patients. H. pylori in the supernatant of the culture medium were observed directly by endocytoscopy. Staphylococcus aureus and red blood cells were used as controls. H. pylori in the culture medium were observed directly by endocytoscopy, and recorded using a video recorder. Live, moving bacteria can be visualized and recorded ex vivo using this new "endocytoscopy" technology.

The clinical applications and accuracy of 2 rapid near-patient tests in detecting Helicobacter pylori infection

Noninvasive methods for assessing Helicobacter pylori infection status are now an integral part of managing patients with upper gastrointestinal complaints. The aim of this study is to evaluate the feasibility and diagnostic accuracy of 2 rapid tests: a urine-based H. pylori antibody detection method (Rapirun) and a stool-based H. pylori antigen detection method (immunocard STAT! HpSA). The combined use of the mentioned 2 tests was also evaluated, which has not been described in previous similar studies. Urine and stool specimens were collected from patients who were arranged for gastroendoscopic examination. The urine and stool specimens were tested with Rapirun and immunocard STAT! HpSA separately. The estimated reaction time was about 15 to 20 min for the former and 5 to 10 min for the latter. H. pylori infection was confirmed with 4 tests: culture, histology, rapid urease test, and the (13)C-urea breath test. Obtained results from both kits were compared with confirmed results. One hundred twenty patients were eligible for analysis. Of them, 62 tested positive for H. pylori infection and 58 were negative by the confirmation criteria. The urine Rapirun test relative to the confirmed results showed sensitivity, specificity, and accuracy as 87.1% (confidence interval [CI] = 81.1-93.1%), 89.7% (CI = 84.2-95.1%), and 88.3%, respectively. The stool immunocard STAT! HpSA test relative to the confirmed results showed sensitivity, specificity, and accuracy as 96.8% (CI = 93.6-99.9%), 82.8% (CI = 76.0-89.5%), and 90%, respectively. The combined-use method of both tests revealed sensitivity, specificity, and accuracy as 98.4% (CI = 96.1-100%), 81.0% (CI = 74.0-88.1%), and 90%, respectively. These 2 urine and stool tests have a satisfactory accuracy around 90% in detecting H. pylori infection. In consideration of the advantages of cheapness, timesaving, and ease of use, both can be used as rapid near-patient tests in general practice. The combined use of both tests was also promising in detecting H. pylori infection.

Diagnosis of Helicobacter pylori infection

A growing interest in non-invasive tests for the detection of Helicobacter pylori has been observed recently, reflecting a large number of studies published this year. New tests have been validated, and the old ones have been used in different clinical situations or for different purposes. Stool antigen tests have been extensively evaluated in pre- and post-treatment settings both in adults and children, and the urea breath test has been studied as a predictor of bacterial load, severity of gastric inflammation, and response to eradication treatment. Several studies have also explored the usefulness of some serologic markers as indicators of the gastric mucosa status. With regard to invasive tests, molecular methods are being used more and more, but the breakthrough this year was the direct in vivo observation of H. pylori during endoscopy.