Age-dependent accuracy of Helicobacter pylori antibody assays for adults, with special emphasis on atrophic gastritis

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.

Association between abnormal gastric function risk and Helicobacter pylori infection assessed by ELISA and 14C-urea breath test

OBJECTIVE

Epidemiological studies found a significant correlation between Helicobacter pylori infection and elevated serum pepsinogen, especially pepsinogen II (PGII), and reduced pepsinogen I (PGI)/PGII ratio. The study aimed to evaluate the association between abnormal gastric function risk and H. pylori infection assessed by H. pylori IgG assay and (14)C-urea breath test (UBT).

METHODS

A total of 1555 subjects who underwent a health check were enrolled. Serum PGI, serum PGII, PGI/PGII ratio, gastrin 17 (G17), H. pylori IgG antibody titer, and UBT results were collected.

RESULTS

Median PGII and G17 levels were higher, but PGI/PGII ratio was lower in H. pylori-seropositive compared with seronegative participants (P<0.001, respectively). Similar effects were demonstrated by UBT. The consistency between H. pylori IgG assay, and UBT results were 86.9%, 82.29%, and 84.64% in individuals with normal gastric function, but only 73.4%, 67.98%, and 74.6% in those with abnormal gastric function. The correlation coefficients for H. pylori infection and abnormal gastric function diagnosed by PGI/PGII <7 were 0.336 (P<0.001) by H. pylori IgG assay and 0.231 (P<0.001) by UBT, diagnosed by PGII ≥ 8.25 µg/L were 0.594(P<0.001) by H. pylori IgG assay and 0.493 (P<0.001) by UBT, diagnosed by G17 >3 pmol/L was 0.469 (P<0.001) by H. pylori IgG assay and 0.394 (P<0.001) by UBT. The odds ratios (ORs) (95% confidence intervals) of abnormal gastric function were 7.477 (5.278-10.594), 19.204 (14.526-25.387), and 7.921 (6.286-9.982) comparing positive versus negative by H. pylori IgG assay and 4.084 (2.98-5.598), 9.552 (7.494-12.174), and 5.402 (4.335-6.731) comparing positive versus negative by UBT.

CONCLUSIONS

H. pylori infection assessments by antibody-based or bacterial component-based detection are both related with abnormal gastric function. Moreover, serum H. pylori IgG assay was stronger associated with abnormal gastric function than UBT assay.

Non-Invasive Diagnosis of Helicobacter pylori: Evaluation of Two Enzyme Immunoassays, Testing Serum IgG and IgA Response in the Anand District of Central Gujarat,India

CONTEXT

Validation of an accurate and less cumbersome noninvasive method to detect current Helicobacter pylori infection is a requisite for any laboratory.

OBJECTIVES

The purpose of this study is to corroborate the usefulness of two commercially available kits NovaTec ELISA-A and ELISA-G, in the detection of ongoing H.pylori infection.

MATERIALS AND METHODS

Two hundred and twenty eight consecutive serum samples of symptomatic patients who attended the endoscopy unit of "Deep" surgical hospital, Anand, which were collected during the period from 27th February 2008 to 31st august 2011, were studied. The sera were processed and tested for the detection of the H.pylori IgG and IgA antibody by using a solid phase; capture micro well ELISA, procured from Nova Tec immunodiagnostica GmbH Germany.

RESULTS

IgG ELISA showed 100% sensitivity and Negative predictive value (NPV), while IgA ELISA was better in terms of specificity (61.4%) and accuracy (63%) as compared to IgG ELISA. We found 7% (16/228) of IgA positive cases with IgG negative response. IgG response was more common in reflux esophagitis patients (OR 1.451, 95%CI-0.850-2.477) and then in gastritis (OR 0.962, 95%CI-0.570-1.621) and duodenitis(OR-0.806, 95%CI-0.112-5.827), while IgA positive response was more common in duodenitis patients (OR-1.383, 95%CI-0.191-9.995) and reflux esophagitis patients (OR 1.289, 95% CI-0.756-2.197) and least in duodenal ulcer patients (OR 0.670, 95%CI-0.222-2.029).

CONCLUSION

IgG update is reliable and accurate test and can be expedient as a screening test and thus serve as an alternative to endoscopy. For the purpose of excluding infection with H.pylori, the performance of IgG is moderate (low specificity) but can be improved by conjunctional IgA testing which will offer some additional diagnostic value.

Motor fluctuations and Helicobacter pylori in Parkinson's disease

The presence of Helicobacter pylori (HP) in the gastrointestinal tract may limit the absorption of levodopa. The objectives of this study were to investigate whether HP infection may affect the clinical response to levodopa as well as levodopa dose requirement in patients with Parkinson's disease (PD) as well as to investigate whether HP infection may affect plasma levels of vitamin B12, folic acid, and homocysteine. Seventy-five patients with PD diagnosed at least 4 years ago were included. Symptom fluctuations were assessed by UPDRS-IV and the WOQ9 wearing-off-scale. Plasma levels of vitamin B12, folic acid, and homocysteine were analyzed. Screening for HP was performed with a 13C-labeled urea breath test (Diabact UBT). A propensity-matched analysis was made where each patient in the HP-infected group was matched with one patient in the non-infected group with respect to age and gender. Of the 75 included patients, 20 were HP infected (27 %). Median Hoehn & Yahr scores were 3 in both HP infected patients and the matched group (n = 20). HP-infected patients had decreased "complications of therapy" with average total UPDRS-IV score of 4.8 ± 3.0 vs. 7.7 ± 3.8 (p < 0.05), despite no significant difference in levodopa equivalent dose. Wearing-off and sleep disturbance were significantly less common in the HP group (p < 0.05). There were no differences regarding vitamin B12, folic acid, or homocysteine values. HP infection in patients with PD may result in a decreased occurrence of symptom fluctuations according to this small study. This finding may be due to altered absorption of levodopa in the gastrointestinal tract in patients with HP infection, but further studies are required.

Correlation of serum antibody titres with invasive methods for rapid detection of Helicobacter pylori infections in symptomatic children

Helicobacter pylori (H. pylori) is causally associated with peptic ulcer disease and gastric carcinoma. Typically, children get infected during the first decade of life, but diseases associated with H. pylori are seen mainly in adults. Multiple diagnostic methods are available for the detection of H. pylori infection. The aim of this study was to evaluate the correlation and diagnostic accuracy of three invasive methods [rapid urease test (RUT), histology and bacterial culture] and one non-invasive method (IgG serology) for diagnosis of H. pylori infection in a prospective cohort study conducted on 50 symptomatic children between two and eighteen years of age. Endoscopies with gastric biopsies were performed for RUT, culture and histopathological examination, respectively. IgG antibodies were measured in patient sera using a commercially available enzyme-linked immunosorbent assay (ELISA). RUT and positive H. pylori IgG antibodies were concordant in 88% (44/50) of patients. Both tests were negative in 32% (16/50), and both were positive in 56% (28/50). Disagreement occurred in 12% (6/50) of the patients: three of them (6%) had positive RUT and negative H. pylori IgG, and another three (6%) had negative RUT and positive H. pylori IgG. A combination of RUT with non-invasive serology constituted the optimum approach to the diagnosis of H. pylori infection in symptomatic children. The non-invasive serological test (ELISA) could not be used alone as the gold standard because it cannot distinguish between active and recently treated infection; and bacterial culture could not be used alone because of its low sensitivity.

Rationale in diagnosis and screening of atrophic gastritis with stomach-specific plasma biomarkers

BACKGROUND AND AIMS

Atrophic gastritis (AG) results most often from Helicobacter pylori (H. pylori) infection. AG is the most important single risk condition for gastric cancer that often leads to an acid-free or hypochlorhydric stomach. In the present paper, we suggest a rationale for noninvasive screening of AG with stomach-specific biomarkers.

METHODS

The paper summarizes a set of data on application of the biomarkers and describes how the test results could be interpreted in practice.

RESULTS

In AG of the gastric corpus and fundus, the plasma levels of pepsinogen I and/or the pepsinogen I/pepsinogen II ratio are always low. The fasting level of gastrin-17 is high in AG limited to the corpus and fundus, but low or non-elevated if the AG occurs in both antrum and corpus. A low fasting level of G-17 is a sign of antral AG or indicates high intragastric acidity. Differentiation between antral AG and high intragastric acidity can be done by assaying the plasma G-17 before and after protein stimulation, or before and after administration of the proton pump inhibitors (PPI). Amidated G-17 will rise if the antral mucosa is normal in structure. H. pylori antibodies are a reliable indicator of helicobacter infection, even in patients with AG and hypochlorhydria.

CONCLUSIONS

Stomach-specific biomarkers provide information about the stomach health and about the function of stomach mucosa and are a noninvasive tool for diagnosis and screening of AG and acid-free stomach.

Immunoglobulin G antibody against Helicobacter pylori is an accurate test for atrophic gastritis

BACKGROUND

Enzyme-linked immunosorbent assay (ELISA) is the most commonly used serologic test for Helicobacter pylori. This study aimed to investigate the effects of age and atrophic gastritis on the diagnostic accuracy of an immunoglobulin G (IgG) antibody test against H. pylori in adults.

METHODS

One hundred and seventy dyspeptic patients (age range, 20-70 years) were evaluated. H. pylori infection was diagnosed when culture or both urease and histological tests were positive. Serum pepsinogen-I (P-I) and pepsinogen-II (P-II) levels were measured. Atrophic gastritis was defined when P-I < or = 70 microg/L and P-I/P-II < or = 3. A quantitative ELISA test (HEL-pTEST II) was used for IgG antibodies against H. pylori.

RESULTS

The H. pylori prevalence rate was 62.1%. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of ELISA were 93.5%, 94.4%, 95.6%, 91.9%, and 93.9% in patients aged < 45 years, and 100%, 81.3%, 94.3%, 100%, and 95.6% in patients aged > or = 45 years, respectively. Twenty-six patients had atrophic gastritis. There was 100% sensitivity and 86.7% specificity in atrophic gastritis and 96.5% sensitivity and 91.9% specificity in non-atrophic gastritis.

CONCLUSION

The quantitative ELISA test is a good noninvasive test even in older age groups and is a suitable test in patients with atrophic gastritis due to its excellent sensitivity.

A "screen-and-treat" approach for Helicobacter pylori infection: a population-based study in Vammala, Finland

BACKGROUND

To accelerate the decline of Helicobacter pylori infection, and to study the significance of the possible risk factors for H. pylori infection in Finland, we started a voluntary H. pylori"screen-treat-retest-and-retreat" program for all young adults at primary health care in Vammala, Finland after a pilot study in 1994 including 504 subjects aged 15-75.

MATERIALS AND METHODS

A total of 3326 aged 15-40 in 1996, and 716 aged 15 and 584 aged 45 in 1997-2000 were screened for H. pylori using serology. Helicobacter pylori positive were treated, cure was verified by serology.

RESULTS

The eradication rates were 93.8%, 82.2%, and 77.6% per protocol in pilot study in 1994, in subjects invited in 1996 and 1997-2000, respectively. Helicobacter pylori seroprevalence rates were calculated to have decreased from 36% to 14% in pilot study, from 12% to 4% among subjects invited in 1996, from 3% to 2% among subjects aged 15 and from 27% to 12% among subjects aged 45 in 1997-2000. An epidemiologic questionnaire in 1996 revealed that crowding in the childhood household, low education of the mother, current smoking and alcohol consumption, unfavorable housing conditions, and sick leaves due to dyspepsia were independently associated with H. pylori infection.

CONCLUSIONS

This intervention with high participation rates resulted in a significant decline in calculated H. pylori seroprevalence rates. Although the low prevalence of H. pylori infection may limit the cost efficiency of the program, the intervention is expected to reduce the burden of H. pylori-associated diseases.

Serum biomarkers provide an accurate method for diagnosis of atrophic gastritis in a general population: The Kalixanda study

OBJECTIVE

Serological biomarkers can be used for non-invasive diagnosis of gastritis and atrophic gastritis. The aim of this study was to compare the validity of serum levels of pepsinogen I (PGI) and II (PGII), gastrin-17 (G-17) and Helicobacter pylori antibodies (Hpab) with that of the gold standard histology for diagnosis of atrophic gastritis in a population sample from Northern Sweden.

MATERIAL AND METHODS

In all, 1000 subjects underwent endoscopies with biopsies. Serum biomarkers were available in 976 subjects for independent diagnosis of gastric mucosal status using a predetermined diagnostic algorithm.

RESULTS

Overall agreement between histology and serological biomarkers in diagnosing corpus atrophy was 96% (CI 95%: 95-97%). Sensitivity and specificity of markers for atrophic gastritis were 71% (CI 68-74%) and 98% (CI 97-99%) respectively, corresponding to 69% (CI 95%: 66-72%) and 98% (95% CI 97-99%) positive and negative predictive values. The positive likelihood ratio was 35.5 (95% CI: 35.0-36.0%). In subgroups with normal stomachs, H. pylori non-atrophic gastritis and H. pylori-negative gastritis by histology, the prevalence of corpus atrophy diagnosed with the biomarkers was 0.8% and 4.9%, respectively. In total, 6.6% of subjects in the study population had corpus atrophy according to the serological biomarkers. CONCLUSIONS. Serological biomarkers show a high degree of accuracy as a non-invasive method to diagnose corpus atrophy, which is common in the general population.

Association of Helicobacter pylori infection with chronic atrophic gastritis: Meta-analyses according to type of disease definition

Helicobacter pylori is a major risk factor for chronic atrophic gastritis (CAG). A large variety of definitions of CAG have been used in epidemiologic studies in the past. The aim of this work was to systematically review and summarize estimates of the association between H. pylori infection and CAG according to the various definitions of CAG. Articles on the association between H. pylori infection and CAG published until July 2007 were identified. Separate meta-analyses were carried out for studies defining CAG based on gastroscopy with biopsy, serum pepsinogen I (PG I) only, the pepsinogen I/pepsinogen II ratio (PG I/PG II ratio) only, or a combination of PG I and the PG I/PG II ratio. Numbers of identified studies and summary odds ratios (OR) (95% confidence intervals) were as follows: gastroscopy with biopsy: n = 34, OR = 6.4 (4.0-10.1); PG I only: n = 13, OR = 0.9 (0.7-1.2); PG I/PG II ratio: n = 8, OR = 7.2 (3.1-16.8); combination of PG I and the PG I/PG II ratio: n = 20, OR = 5.7 (4.4-7.5). Studies with CAG definitions based on gastroscopy with biopsy or the PG I/PG II ratio (alone or in combination with PG I) yield similarly strong associations of H. pylori with CAG. The association is missed entirely in studies where CAG is defined by PG I only.

CagA and VacA are immunoblot markers of past Helicobacter pylori infection in atrophic body gastritis

BACKGROUND AND AIM

Atrophic body gastritis (ABG) may be induced by H. pylori infection. It is difficult to diagnose H. pylori infection in this condition, since during progression of body atrophy the bacterium disappears. In 30% of patients with ABG no sign of H. pylori infection is detectable. We aimed to investigate whether patients with ABG, classified as H. pylori-negative by conventional methods (ELISA serology and Giemsa stain histology), have been previously exposed to the infection.

METHODS

Case series consisted of 138 outpatients with ABG, of whom 31 are H. pylori negative (histology and ELISA serology), and 107 are H. pylori related (histology and ELISA serology positive: active infection, n = 29; only serology positive: past infection, n = 78). Thirty control subjects who were H. pylori negative at histology and ELISA serology were investigated. Immunoblotting of sera against H. pylori whole-cell protein lysate was performed.

RESULTS

None of the control sera recognized CagA, VacA, heat-shock protein B, and urease B, yielding a specificity of 100%. All H. pylori-negative patients with ABG showed immunoblotting seroreactivity, including in each case either CagA or VacA. The concomitant seroreactivity against CagA and VacA was highly prevalent in the H. pylori-negative patients with ABG, comparable to those with active infection (77.4% vs. 86.2%) and with past infection (vs. 61.5%).

CONCLUSIONS

Immunoblotting against CagA and VacA is able to prove past exposure to H. pylori infection in all patients with ABG defined as H. pylori-negative by conventional methods, suggesting a hidden role of H. pylori infection in gastric atrophy also in these patients.

IgA antibodies in persisting Helicobacter pylori infection in Finnish adults

Most individuals infected with Helicobacter pylori have elevated levels of specific IgG antibodies, but only in about two-thirds of cases does the IgA titre exceed the cut-off level. The aim of this study was to determine whether H. pylori-infected subjects with elevated IgG levels would subsequently produce IgA antibodies, and whether elevated IgA levels increased during infection. Paired sera were available from 336 adults who took part in a large population-based health survey in 1977-1980 and a follow-up study on asthma and atopic diseases in 1997-1998 (series A). Data on paired sera from 224 adults who participated in a population-based health survey in Vammala, Finland in 1973 and who gave a follow-up blood sample in 1994 (series B) were also re-analysed. H. pylori IgG and IgA levels were determined with commercially available (series A) and in-house (series B) enzyme immunoassays. Twenty-one (35%) of the 60 subjects who initially had elevated levels of IgG antibodies only were found to be IgA-positive at follow-up. In those subjects whose baseline and follow-up samples were IgG- and IgA-positive, the median IgA levels increased by 48% and 22% in series A and B (p < 0.0001 and p 0.0241), respectively, whereas the median IgG levels did not change significantly in either series. During H. pylori infection, an increase in specific IgA was reflected by the increase in the number of responders and by the rise in titres.

Diagnosis of Helicobacter pylori Infection

A large number of studies on diagnostic tests have been published this year. New tests were proposed for the detection of Helicobacter pylori antigens in stools and new molecular methods (real-time polymerase chain reaction) to look for antimicrobial susceptibility. The other standard tests have been applied in different situations to improve the diagnosis of the infection.