Systematic Review and Meta-Analysis on the Sensitivity and Specificity of 13C/14C-Urea Breath Tests in the Diagnosis of Helicobacter pylori Infection

Helicobacter pylori (H. pylori) continues to be a major health problem worldwide, causing considerable morbidity and mortality due to peptic ulcer disease and gastric cancer. The aim of the present systematic review and meta-analysis was to determine the sensitivity and specificity of 13C/14C-urea breath tests in the diagnosis of H. pylori infection. A PRISMA systematic search appraisal and meta-analysis were conducted. A systematic literature search of PubMed, Web of Science, EMBASE, Scopus, and Google Scholar was conducted up to August 2022. Generic, methodological and statistical data were extracted from the eligible studies, which reported the sensitivity and specificity of 13C/14C-urea breath tests in the diagnosis of H. pylori infection. A random effect meta-analysis was conducted on crude sensitivity and specificity of 13C/14C-urea breath test rates. Heterogeneity was assessed by Cochran’s Q and I2 tests. The literature search yielded a total of 5267 studies. Of them, 41 articles were included in the final analysis, with a sample size ranging from 50 to 21857. The sensitivity and specificity of 13C/14C-urea breath tests in the diagnosis of H. pylori infection ranged between 64−100% and 60.5−100%, respectively. The current meta-analysis showed that the sensitivity points of estimate were 92.5% and 87.6%, according to the fixed and random models, respectively. In addition, the specificity points of estimate were 89.9% and 84.8%, according to the fixed and random models, respectively. There was high heterogeneity among the studies (I2 = 98.128 and 98.516 for the sensitivity and specificity, respectively, p-value < 0.001). The 13C/14C-urea breath tests are highly sensitive and specific for the diagnosis of H. pylori infection.

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.

Simplified 13C-urea breath test for detection of Helicobacter pylori infection

OBJECTIVE

The U.S. standard 13C-urea breath test (13C-UBT) has proven to be extremely reliable but entails several complicated performance requirements and a test period of approximately 1 h. The aim of this study was to compare the standard 13C-UBT with a simplified version embodying modifications of test meal, duration of fasting, amount of 13C-urea, method of breath collection, and duration of test.

METHODS

This was a randomized, three-way, crossover study of the standard U.S. 13C-UBT, which contains 125 mg of 13C-urea and a pudding test meal. The final breath sample is taken 30 min after urea ingestion. This test was compared with a formulation containing 75 mg of 13C-urea, a 2.5-g citric acid test meal (UBT-Lite), and a final breath sample taken by direct exhalation into tubes 15 min after urea ingestion. We also compared the effect of prior meals versus fasting on the test outcome with the UBT-Lite.

RESULTS

A total of 259 subjects were enrolled in the trial, and 249 completed all three urea breath tests. There was excellent agreement between the three versions of the UBT with >98% of subjects having concordant results. Using predetermined criteria, there was substantial equivalence between the tests. Neither solid and/or liquid food up to 1 h before performing the UBT-Lite affected outcome.

CONCLUSION

The UBT-Lite formulation of the 13C-UBT proved to be an improved version of the U.S. standard 13C-UBT offering less expensive ingredients, shorter test duration, and a simplified breath test collection method, without sacrificing accuracy.

Implications of Helicobacter pylori infection for stomach cancer prevention

Accumulating evidence has implicated Helicobacter pylori, an established cause of chronic gastritis and peptic ulcer, in the etiology of gastric cancer. Control of this infection would reduce the occurrence of chronic gastritis and peptic ulcer and might substantially lower the risk of stomach cancer as well. The public health impact of this infectious agent warrants efforts to identify preventive measures. This paper reviews the evidence linking H. pylori infection to gastric cancer and evaluates the potential for control in high-risk populations. Current obstacles to H. pylori control are discussed, including the link to poor socioeconomic conditions, difficulty in identifying incident cases, lack of natural immunity to reinfection, limited effectiveness of antibiotic therapy in high-prevalence populations, and incomplete knowledge regarding the reservoir of infection, mode of transmission, host susceptibility factors, and the potential for developing an effective vaccine. Worthwhile avenues of research include studies designed to identify modifiable risk factors for acquisition of the infection, modifiable host factors that may increase resistance to chronic infection, more effective antibiotic therapies, and effective vaccines.

Comparison of helisal rapid blood test and 14C-urea breath test in determining Helicobacter pylori status and predicting ulcer disease in dyspeptic patients

OBJECTIVE

Noninvasive tests for Helicobacter pylori are used increasingly. Our aim was to compare the Helisal Rapid Blood (HRB) test and 14C-urea breath test (UBT) for determining H. pylori status and predicting ulcer disease.

METHODS

Three hundred fifty-one consecutive patients with dyspepsia (mean age 40 yr; range 16-77 yr) had an HRB test and UBT followed by endoscopy with biopsies of the antrum and body for histology and antral urease slide test (CLO test). Patients were excluded if they had previously confirmed ulcer disease, gastric surgery, or anti-H. pylori therapy or were taking nonsteroidal anti-inflammatory drugs.

RESULTS

Sixty-three percent of the patients were "gold standard" H. pylori positive (positive CLO test, positive staining), 34% were gold standard negative (negative CLO test, negative staining), and 3% had conflicting CLO test and histology. The UBT was superior to HRB for determining H. pylori status (sensitivity 98% vs 92%, p = 0.04; specificity 100% vs 69%, p < 0.001). The specificity of the HRB decreased with increasing patient age (74% for age <46 yr; 57% for age > or =46 yr). A negative UBT was superior to a negative HRB test for predicting the absence of ulcer disease (47% vs 36 %; p < 0.01). A positive UBT was similar to a positive HRB in predicting the presence of ulcer disease (92% vs 84%; p = 0.23).

CONCLUSIONS

The HRB test is inferior to the UBT for determining H. pylori status. The tests have a similar ability to predict the presence of ulcer disease when positive, but a negative UBT is a better predictor of the absence of ulcer disease.

Twenty-minute fasting version of the US 13C-urea breath test for the diagnosis of H. pylori infection

BACKGROUND

In large-scale multi-center clinical trials, the US 13C-urea breath test (UBT) has proven to have a sensitivity and specificity of approximately 95%. Ingestion of a meal to delay gastric emptying has advantages of increasing the level of signal as well as prolonging the duration of significantly increased 13C excretion, at the expense of requiring 40 to 60 minutes to complete the test. Our aim was to explore the utility of the 13C-UBT with a total duration of 30 minutes or less.

METHODS

After a baseline breath sample was obtained, 125 mg of 13C-urea was given in 100 ml of water, and additional breath samples were taken after 20 and 30 minutes. The results of the UBT were compared to histological assessment, culture, and the rapid urease test. 13C-UBTs were carried out on normal volunteers who underwent gastroscopy during which six mucosal biopsies were taken. Three biopsies were for histological evaluation (Genta stain), two for culture, and one was for agar gel rapid urease testing. The UBT was conducted 2 to 3 days either before or after the endoscopic procedure.

RESULTS

The cutoff value for a positive UBT was enrichment of 2.4 delta/1000 (delta over baseline). Of the 66 tests, 51/1000 were Helicobacter pylori-positive. There were no false positive UBTs and only two false negative UBTs at 20 minutes (sensitivity, 96%; specificity, 100%). At 30 minutes, one other UBT was false negative (gray zone of 2.36/1000) (sensitivity, 94%; specificity, 100%).

CONCLUSION

These results suggest that omission of the meal and shortening the duration of the US 13C-UBT to 20 minutes still may maintain excellent specificity and sensitivity of the test.

Role of Helicobacter pylori serology in evaluating treatment success

Duodenal ulcer recurrence and gastritis are reduced with successful Helicobacter pylori treatment. Serology is accurate in the diagnosis of H. pylori, but its value in determining eradication is unproved. To evaluate the usefulness of serology in monitoring treatment, we measured serial serum antibodies in three patient groups: eradication success (N = 57), eradication failure (N = 19), and untreated patients (N = 24). Eradication was determined by Warthin Starry staining of antral biopsies and repeat 13C breath tests at six weeks. Subsequent 13C breath tests were then performed at three-month intervals to monitor eradication. IgG antibody concentrations to H. pylori were determined by a commercially available ELISA kit. Serology concentrations remained constant throughout the study period in the untreated patients. IgG concentrations decreased slightly in the treatment failure group at six weeks but thereafter remained at baseline values. In the eradicated group, serum IgG concentrations decreased 26% by three months, 43% by six months and 55% at nine and 12 months (P < 0.001). A 20% reduction in IgG concentrations by six months was associated with successful treatment (sensitivity 86% and specificity 88%). We conclude that serology is a potentially useful way to monitor H. pylori treatment success.

Use of a urea breath test versus invasive methods to determine the prevalence of Helicobacter pylori in Zaire

The prevalence of Helicobacter pylori infection in Zaire was determined by means of a [14C] urea breath test in 133 asymptomatic subjects, by culture and histological examination of biopsies in 324 consecutive endoscopy patients with chronic epigastric complaints, and by both the breath test and culture/histology in a subset of 92 patients. Sixty healthy Belgian students or hospital laboratory workers were also included for comparison. The prevalence of Helicobacter pylori was significantly higher in asymptomatic Zairian subjects (77.4%) than in the Belgians (30%; p less than 10(-6)). Infection was also acquired much earlier in life in Africans, 66% of the children aged 5 to 9 years already being infected versus none of the Belgian subjects below the age of 20 years. In Zaire, however, the prevalence of Helicobacter pylori in patients with gastroduodenal disorders (87.5%) was similar to that in the group of asymptomatic subjects (77.5%) after adjustment for age and other epidemiological parameters (gender, place of residency, education level, smoking and drinking habits) in a multivariate analysis. The high rate of acquisition of Helicobacter pylori infection in Zaire emphasizes the need to consider the baseline prevalence of Helicobacter pylori in a defined population when studying its association with various diseases.

A comparison of diagnostic tests to determine Helicobacter pylori infection

Twenty-five Helicobacter pylori positive and 25 H. pylori negative subjects as defined by culture and phase contrast microscopy of antral biopsy specimens obtained from routine upper endoscopy were studied. Antral biopsies were examined by rapid urease test, phase contrast microscopy, culture and histology. Venous blood was tested for H. pylori specific IgG antibodies by an ELISA technique. Within 7 days of endoscopy the patients also had a [14C]-urea breath test. The sensitivity and specificity of the rapid urease test was 92%, the breath test 96% and 100%, histopathology 96% and 91% and serology 96% and 88%, respectively. The [14C]-urea breath test performed over 1 h with sampling of subjects at 0, 0.5 and 1 h was an accurate and reliable method. Results expressed as counts per minute of the expired 14CO2 proved to be a simple method of assessing H. pylori status. A significant correlation between severity of histological antral gastritis and the amount of 14CO2 expired was observed. This study has shown that the non-invasive 14C-urea breath test and serology are highly sensitive and specific for the diagnosis of H. pylori infection.

Helicobacter pylori infection in children

Helicobacter pylori was sought prospectively by culture of antral biopsy, histology and serology (IgG and IgA) in 440 consecutive endoscopies on children to determine the prevalence, clinical presentation and histological features of H. pylori infection in our population. Twenty-eight patients had H. pylori (8% overall). The mean age of infected patients was significantly higher than that of non-infected patients (P less than 0.0001). No patient under 5 years of age had H. pylori isolated. Overall, there was no significant difference in clinical presentation between those with and those without H. pylori infection, but 23% of patients 5 and 26 years of age who presented with abdominal pain as the indication for their endoscopy had H. pylori isolated. Macroscopic changes ranged from no abnormality to frank ulceration, but the typical antral mamilliform changes were 100% predictive of infection. Fifty-eight per cent of patients with duodenal ulcers, but only 17% with gastric ulcers had H. pylori infection. Histological gastritis was present in 144 patients (including all H. pylori positive patients). None of the patients with another definable cause for gastritis had H. pylori isolated. In conclusion, H. pylori is an important cause of primary gastritis in our population, occurring in children over 5 years of age. Culture of an antral biopsy should be performed in children over this age undergoing endoscopy for the investigation of abdominal pain and, more particularly, in those with peptic ulceration.