Validation of [13C]urea breath test for Helicobacter pylori using a simple gas chromatograph-mass selective detector

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.

The response of Asian patients with functional dyspepsia to eradication of Helicobacter pylori infection

OBJECTIVES/BACKGROUND

The role of Helicobacter pylori infection in functional dyspepsia (FD) remains controversial. Several randomized controlled trials involving populations in the West, observed no statistically significant advantage over placebo. However, none of these studies involved Asian populations which have high infection rates.

METHODS

A double blind, randomized, placebo-controlled trial of H. pylori eradication for FD was conducted in our Singapore-based Asian population. Forty-one patients received active treatment consisting of a 1-week course of omeprazole 20 mg once daily, clarithromycin 250 mg twice daily and tinidazole 500 mg twice daily whereas another 41 patients received matching placebo tablets. A dyspepsia score was derived by grading 5 dyspeptic symptoms on a Likert scale. Symptom assessment and urea breath test were repeated at 6 weeks, 6 and 12 months from the start of treatment. The primary end point was symptom resolution, defined as a dyspepsia score of 0 or 1 at the end of 12 months follow-up.

RESULTS

On intention-to-treat analyses, symptom resolution was observed in 24% of patients on active treatment and 7% on placebo; the difference in proportion of patients with symptom resolution was statistically significant (P=0.02, 95% confidence interval: 1.1-17.7). H. pylori eradication rates perprotocol and intention-to-treat were 80.0 and 68.3%, on active treatment and 5.6 and 4.9% on placebo (both P values<0.0001). Among patients with H. pylori eradicated on active treatment the symptom resolution rate was 39% (10 of 26), whereas it was 3% (one of 35) among patients in the placebo group who had persistent H. pylori infection. In multivariate analysis, posttreatment H. pylori status was the only predictor of symptom resolution. The majority of patients, 91.5%, had ulcer-like dyspepsia; heartburn and acid regurgitation were uncommon, and no increase was observed after treatment.

CONCLUSION

In contrast to Western populations, our results suggest that patients with FD in Asia would benefit from treatment for H. pylori infection with as much as a 13-fold increased chance of symptom resolution following its eradication.

Cost effectiveness analysis of population-based serology screening and 13C-Urea breath test for Helicobacter pylori to prevent gastric cancer: A markov model

AIM: To compare the costs and effectiveness of no screening and no eradication therapy, the population-based Helicobacter pylori (H pylori) serology screening with eradication therapy and ¹³C-Urea breath test (UBT) with eradication therapy.

METHODS: A Markov model simulation was carried out in all 237 900 Chinese males with age between 35 and 44 from the perspective of the public healthcare provider in Singapore. The main outcome measures were the costs, number of gastric cancer cases prevented, life years saved, and quality-adjusted life years (QALYs) gained from screening age to death. The uncertainty surrounding the cost-effectiveness ratio was addressed by one-way sensitivity analyses.

RESULTS: Compared to no screening, the incremental cost-effectiveness ratio (ICER) was $16 166 per life year saved or $13 571 per QALY gained for the serology screening, and $38 792 per life year saved and $32 525 per QALY gained for the UBT. The ICER was $477 079 per life year saved or $390 337 per QALY gained for the UBT compared to the serology screening. The cost-effectiveness of serology screening over the UBT was robust to most parameters in the model.

CONCLUSION: The population-based serology screening for H pylori was more cost-effective than the UBT in prevention of gastric cancer in Singapore Chinese males.

Cost-effectiveness analysis of Helicobacter pylori screening in prevention of gastric cancer in Chinese

OBJECTIVES

The aim of this study was to evaluate the costs and effectiveness associated with no screening, Helicobacter pylori serology screening, and the 13C-urea breath test (UBT) for gastric cancer in the Chinese population.

METHODS

A Markov model simulation was carried out in Singaporean Chinese at 40 years of age (n = 478,500) from the perspective of public healthcare providers. The main outcome measures were costs, number of gastric cancer cases prevented, life-years saved, quality-adjusted life-years (QALYs) gained from the screening age to death, and incremental cost-effectiveness ratios (ICERs), which were compared among the three strategies. The uncertainty surrounding ICERs was addressed by scenario analyses and probabilistic sensitivity analysis using Monte Carlo simulation.

RESULTS

The ICER of serology screening versus no screening was $25,881 per QALY gained (95 percent confidence interval (95 percent CI), $5,700 to $120,000). The ICER of UBT versus no screening was $53,602 per QALY gained (95 percent CI, $16,000 to $230,000). ICER of UBT versus serology screening was $470,000 per QALY gained, for which almost all random samples of the ICERs distributed above $50,000 per QALY.

CONCLUSIONS

It cannot be confidently concluded that either H pylori screening was a cost-effective strategy compared with no screening in all Chinese at the age of 40 years. Nevertheless, serology screening has demonstrated much more potential to be a cost-effective strategy, especially in the population with higher gastric cancer prevalence.

An optimized 13C-urea breath test for the diagnosis of H pylori infection

AIM: To validate an optimized 13C-urea breath test (¹³C-UBT) protocol for the diagnosis of H pylori infection that is cost-efficient and maintains excellent diagnostic accuracy.

METHODS: 70 healthy volunteers were tested with two simplified ¹³C-UBT protocols, with test meal (Protocol 2) and without test meal (Protocol 1). Breath samples were collected at 10, 20 and 30 min after ingestion of 50 mg ¹³C-urea dissolved in 10 mL of water, taken as a single swallow, followed by 200 mL of water (pH 6.0) and a circular motion around the waistline to homogenize the urea solution. Performance of both protocols was analyzed at various cut-off values. Results were validated against the European protocol.

RESULTS: According to the reference protocol, 65.7% individuals were positive for H pylori infection and 34.3% were negative. There were no significant differences in the ability of both protocols to correctly identify positive and negative H pylori individuals. However, only Protocol 1 with no test meal achieved accuracy, sensitivity, specificity, positive and negative predictive values of 100%. The highest values achieved by Protocol 2 were 98.57%, 97.83%, 100%, 100% and 100%, respectively.

CONCLUSION: A 10 min, 50 mg ¹³C-UBT with no test meal using a cut-off value of 2-2.5 is a highly accurate test for the diagnosis of H pylori infection at a reduced cost.

[Is the breath test reliable in primary care diagnosis of Helicobacter pylori infection?]

OBJECTIVE

To evaluate the reliability of the breath test urea 13C in the primary care for the diagnosis of Helicobacter pylori (Hp) infection.

DESIGN

Descriptive, prospective and multicentric.Location. Urban area belonging to the Health Center Actur Sur of Zaragoza with participation of Miguel Servet Hospital.

PARTICIPANTS

87 patients with clinical diagnosis of functional dispepsia. In all of them was made a breath test with 13C urea as well as a gastroscopy with taking of samples for histology and ureasa fast test.

MAIN MEASUREMENTS

Age, sex and the presence of positivity or negativity of infection by Hp were valued in the histology, ureasa test and in the breath test, considering the histology and the ureasa test like gold tests for this measurement, reason why it was demanded that the positive or outside negative result in both considering it nonambiguous.

RESULTS

Two cases were excluded by ambiguous results. The 77.6% (66/85) were positive by histology and ureasa test, and these, 92.4% (61/66) were positives to the breath test. The sensitivity of this test was 92% and the specificity 100%.

CONCLUSIONS

The breath test in primary care has a high value diagnosis of Hp infection, being able to avoid, in some cases, another invasives techniques like gastroscopy.

Non-invasive testing for Helicobacter pylori

Confirmed and potential benefits of eradicating Helicobacter pylori have led to the development of a range of diagnostic tests. As well as techniques using biopsy tissue obtained during endoscopy, a number of non-invasive tests are now available. These may be appropriate for pre-endoscopy screening of younger dyspeptics, for use in research, particularly epidemiological surveys, to confirm successful eradication after treatment, and possibly in the future for screening in asymptomatic populations. Serology requiring laboratory analysis is likely to be the least expensive option, particularly suitable for testing large numbers, while urea breath tests should yield the most accurate results and are appropriate for confirming successful eradication since only current infection is detected. The performance of near-patient tests can lack consistency, but these may be useful for small numbers and where other non-invasive testing is unavailable. Tests should be used with an awareness of their potential limitations in terms of accuracy.