The diagnostic value of endoscopy and Helicobacter pylori tests for peptic ulcer patients in late post-treatment setting

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.

Prevalence of esophageal cancer in the Northern part of Afghanistan

BACKGROUND

Esophagogastroduodenoscopy (EGD) is the standard technique for diagnosis of patients presenting with upper gastrointestinal symptoms. Some reports have shown high prevalence of esophageal cancer in the northern part of Afghanistan. The aim of this study was to investigate epidemiological profile of esophageal cancer among patients in this region.

MATERIALS AND METHODS

We identified 364 consecutive patients that received EGD examinations to examine upper gastrointestinal tract at the endoscopy unit of Balkh regional Hospital from March 2012 to March 2013. The case subjects included both in-patients and out-patients aged 16 years or more. We evaluated the results retrospectively.

RESULTS

The cases consisted of 184 (51%) males and 180 (49%) females. The mean age was 47.3±17.8 and the age range 17-88 years. Ninety two cases had esophageal cancer, out of which 58 (63.0%) were male. The mean age at time of diagnosis was 57.8±13.2 years. Uzbek-Turkmen peoples were more common among patients with esophageal cancer (52.2%). Dysphagia was the most frequent symptom among patients with esophageal cancer at the time of presentation, seen in 77 (84.8%) of cases.

CONCLUSIONS

Our results showed high incidence of esophageal cancer in the northern part of Afghanistan, especially in the Uzbek-Turkmen ethnic group.

Persistence of Helicobacter pylori infection in patients with peptic ulcer perforation

OBJECTIVE

In patients with perforated peptic ulcer (PPU) the convergence between the high eradication rate of Helicobacter pylori infection and low rates of ulcer relapse after treatment has been associated with reinfection by non-virulent strains. The objective of this study was to evaluate the persistence of infection by virulent H. pylori strains and ulcer recurrence in 33 patients with PPU one year after surgery and antimicrobial treatment.

MATERIAL AND METHODS

The histological evaluation and molecular detection of H. pylori cagA and ureA genes, vacA allelic types and the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analyses of the glmM gene products from antral mucosa specimens were performed initially, 2-5 months and 1 year after therapy.

RESULTS

The density of H. pylori colonization was temporarily decreased (p<0.05) 2-5 months after therapy. After one year, complete eradication was achieved in only 7 patients (23%) at histological examination and recurrent ulcers were found in 3/33 (9%) patients. The vacA s1a allelic type of cagA-positive strains persisted in 19/33 (58%) PPU patients with identical PCR-RFLP fingerprints in 8/9 (89%) of the patients.

CONCLUSIONS

In PPU patients with a low eradication rate of H. pylori infection after surgical and antimicrobial treatment, the frequent recrudescence of the infection is mostly caused by the persisting virulent strains of the cagA and vacA s1a subtypes. In the 1-year follow-up period the recurrent ulceration can be postponed just by the lowered colonization density of H. pylori after eradicative therapy.

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.