13C urea breath test with nondispersive isotope-selective infrared spectrometry: reproducibility and importance of the fasting status

European guideline on indications, performance and clinical impact of 13 C-breath tests in adult and pediatric patients: An EAGEN, ESNM, and ESPGHAN consensus, supported by EPC

Introduction

¹³C‐breath tests are valuable, noninvasive diagnostic tests that can be widely applied for the assessment of gastroenterological symptoms and diseases. Currently, the potential of these tests is compromised by a lack of standardization regarding performance and interpretation among expert centers.

Methods

This consensus‐based clinical practice guideline defines the clinical indications, performance, and interpretation of ¹³C‐breath tests in adult and pediatric patients. A balance between scientific evidence and clinical experience was achieved by a Delphi consensus that involved 43 experts from 18 European countries. Consensus on individual statements and recommendations was established if ≥ 80% of reviewers agreed and <10% disagreed.

Results

The guideline gives an overview over general methodology of ¹³C‐breath testing and provides recommendations for the use of ¹³C‐breath tests to diagnose Helicobacter pylori infection, measure gastric emptying time, and monitor pancreatic exocrine and liver function in adult and pediatric patients. Other potential applications of ¹³C‐breath testing are summarized briefly. The recommendations specifically detail when and how individual ¹³C‐breath tests should be performed including examples for well‐established test protocols, patient preparation, and reporting of test results.

Conclusion

This clinical practice guideline should improve pan‐European harmonization of diagnostic approaches to symptoms and disorders, which are very common in specialist and primary care gastroenterology practice, both in adult and pediatric patients. In addition, this guideline identifies areas of future clinical research involving the use of ¹³C‐breath tests.

The Urea Breath Test for the Noninvasive Detection of Helicobacter pylori

The concept of the urea breath test (UBT), as a method for H. pylori detection, is based on the ability of the H. pylori urease enzyme to break down an isotope-labelled urea solution ingested by the patient into carbon dioxide (CO₂) and ammonia. This chapter summarizes the current use of the UBT and the utility of the "UBT and Treat" strategy compared to other strategies for the management of H. pylori infection . Different UBT methods are described as well as factors affecting the accuracy of the test.

PROSPECTIVE STUDY FOR VALIDATION OF A SINGLE PROTOCOL FOR THE 13C-UREA BREATH TEST USING TWO DIFFERENT DEVICES IN THE DIAGNOSIS OF H. PYLORI INFECTION

BACKGROUND

13C-urea breath test (UBT) is the gold-standard, noninvasive method for H. pylori diagnosis. However, there is no uniform standardization of the test. This situation can be unpractical for laboratories running with two or more devices.

OBJECTIVE

To perform a prospective comparison validation study of UBT employing one validated protocol for two different devices: BreathID Hp Lab System® (Exalenz Bioscience Ltd, Israel), here called device A and IRIS-Doc2® (Wagner Analysen-Technik, Germany, now Mayoly Spindler Group, France), here called device B, in the diagnosis of H. pylori infection.

METHODS

A total of 518 consecutive patients (365 females, 153 males, mean age 53 years) referred for UBT were included. All patients received device A protocol as follow: after at least one hour fasting, patients filled two bags prior to the test, then ingested an aqueous solution containing 75 mg of 13C-urea with a 4.0 g citric acid powder and filled another two bags 15 min after ingesting the test solution. One pair of breath sample bags (before and after ingestion) was analyzed by the two different devices. A delta over baseline (DOB) ≥5‰ indicated H. pylori infection. Statistics: Wilcoxon test, kappa coefficient with 95% CI, Wilson's method.

RESULTS

Considering the device A protocol as the gold standard, its comparison with device B showed a sensitivity of 99.3% (95% CI: 96.3-99.9) and a specificity of 98.9% (95% CI: 97.3-99.6). Kappa coefficient was 0.976 (95% IC: 0.956-0.997).

CONCLUSION

Correlation between the two devices was excellent and supports a uniform standardization of UBT.

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.

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.

[Breath tests in the diagnosis of gastrointestinal diseases]

Determination of carbon or hydrogen markers in breath has allowed closer investigation of the pathogenic mechanisms of several gastrointestinal diseases. Thus, the 13C-urea breath test is a nonaggressive, simple and safe test with excellent accuracy both in the initial diagnosis of Helicobacter pylori infection and in confirmation of its eradication following treatment. Moreover, because of the simplicity, reproducibility and safety of these types of procedure, they have tended to substitute more uncomfortable and expensive techniques that were traditionally used in gastroenterology. Several breath tests have been developed that allow reliable evaluation of liver or exocrine pancreatic function, gastrointestinal motility, as related to gastric emptying or orocecal transit time, and a diagnostic approach to clinical problems that could be due to bacterial overgrowth or malabsorption of various sugars.

The early effect of proton pump inhibitor therapy on the accuracy of the 13C-urea breath test

BACKGROUND

The intake of proton pump inhibitors may interfere with the reliability of the urea breath test.

AIM

Prospective study to assess the accuracy of the urea breath test during the first days of therapy with proton pump inhibitors.

PATIENTS

Thirty patients who needed to start proton pump inhibitors therapy and 53 volunteers.

METHODS

A 13C-urea breath test was performed respectively before starting proton pump inhibitors therapy and every morning before its intake up until 10 days. The test was considered positive for values of 13CO2 > or = 3.0% delta over baseline. The coefficient of reproducibility for 95% interval of confidence of the urea breath test was calculated in both groups.

RESULTS

Of the 30 patients receiving proton pump inhibitors, 47% were positive for Helicobacter pylori. Among these, 43% developed false negative breath tests in the first 10 days. False positive results occurred in 37.5% of H. pylori-negative subjects in the first 10 days. The coefficient of reproducibility of the urea breath test was significantly higher in the group treated with proton pump inhibitors (11.0 versus 1.8 for the control group, p < 0.0001).

CONCLUSION

The intake of proton pump inhibitors impairs the accuracy of the 13C-urea breath test. False negative and false positive 13C-urea breath tests are common, occur as soon as after 1 day and increase with prolonged duration of treatment. The coefficient of reproducibility of the test in patients receiving proton pump inhibitors is not acceptable for clinical purpose and the test should not be performed once the medication has been started.

Review article: 13C-urea breath test in the diagnosis of Helicobacter pylori infection -- a critical review

The urea breath test is a non-invasive, simple and safe test which provides excellent accuracy both for the initial diagnosis of Helicobacter pylori infection and for the confirmation of its eradication after treatment. Some studies have found no differences between urea breath test performed under non-fasting conditions. The simplicity, good tolerance and economy of the citric acid test meal probably make its systematic use advisable. The urea breath test protocol may be performed with relatively low doses (<100 mg) of urea: 75 mg or even 50 mg seem to be sufficient. With the most widely used protocol (with citric acid and 75 mg of urea), excellent accuracy is obtained when breath samples are collected as early as 10-15 min after urea ingestion. A unique and generally proposed cut-off level is not possible because it has to be adapted to different factors, such as the test meal, the dose and type of urea, or the pre-/post-treatment setting. Fortunately, because positive and negative urea breath test results tend to cluster outside of the range between 2 and 5 per thousand, a change in cut-off value within this range would be expected to have little effect on clinical accuracy of the test.

[Comparison between two 13C-urea breath tests for the diagnosis of Helicobacter pylori infection: isotope ratio mass spectrometer versus infrared spectrometer]

OBJECTIVES

To compare the accuracy of the breath test using the isotope ratio mass spectrometer (IRMS) versus the nondispersive isotope-selective infrared spectrometer (NDIRS) in the diagnosis of Helicobacter pylori infection.

METHOD

Multicenter study in 4 Spanish hospitals. One group of dyspeptic patients who had not undergone prior eradication therapy and another group of patients with gastric ulcer or gastrointestinal bleeding due to gastroduodenal ulcer receiving H. pylori eradication therapy were included in the study. A reference standard based on histology and the rapid urease test was used. The breast test (TAU-KIT, Isomed S.L., Madrid, Spain) was performed with citric acid and 100 mg of 13C-urea. Samples of expired air were collected in tubes and bags for reading with the IRMS (ABCA, PDZ, Crewe, Manchester, England) and the NDIRS (UBiT-IR200, Otsuka Electronics, Co, Osaka, Japan), respectively. The endoscopist, pathologist and person responsible for reading the urease test and both breath tests were blinded to the results of the other diagnostic methods.

RESULTS

Forty-one patients were included. The prevalence of H. pylori was 26%. No differences were found on comparing the mean values obtained with the IRMS and the NDIRS: 13 (standard deviation) (24) and 14 (25) delta units, respectively. The area under the ROC curve for the IRMS and the NDIRS was 0.96. The diagnostic accuracy for the best cut-off point with the IRMS and the NDIRS was, respectively: sensitivity (90 and 100%), specificity (96 and 89%), positive predictive value (90 and 77%), negative predictive value (96 and 100%), + likelihaod ratio (25 and 9.3) and (0.1 and 0). A close correlation was found between the values of the IRMS and those of the NDIRS (lineal regression equation, Y = 1.1 + 1.004. X; r = 0.97).

CONCLUSION

Both the spectrometers used to evaluate the breath test, the IRMS and the NDIRS, offer a high degree of accuracy in the diagnosis of H. pylori infection.

Five minute endoscopic urea breath test with 25 mg of (13)C-urea in the management of Helicobacter pylori infection

OBJECTIVE

The endoscopic (13)C-urea breath test ((13)C-EUBT), which combines the urea breath test (UBT) with endoscopy, provides high accuracy for the detection of Helicobacter pylori. This study was conducted to determine whether the (13)C-EUBT using low doses of urea and short sampling times could preserve accuracy in the management of H. pylori infection.

METHODS

Three hundred and twenty-five patients were randomized to receive the EUBT with 100, 50 or 25 mg of (13)C-urea by endoscopic spraying. The breath samples collected at 5, 10 and 20 min were analysed using an isotope selected non-dispersive infrared spectrometer. H. pylori infection was assessed by the rapid urease test and histology. In each sampling schedule and protocol, cut-off values were calculated by a receiver operating characteristic curve. We applied the EUBT with 25 mg of (13)C-urea at 5 min to the assessment of eradication in 135 patients who had received the antimicrobial treatment or to the detection of the organism in 61 patients with previous partial gastrectomy.

RESULTS

Based on histology and the urease test, patients who had discordant results were excluded from the analysis. Using 100 mg of urea, the sensitivity and specificity of the test were both 100% at 10 and 20 min, and the sensitivity and specificity at 5 min were best with 98.6% and 100%, respectively. With 50 mg, they were both 100% at 20 min, and the best combination of sensitivity and specificity at 5 and 10 min was 97.3-96.6% and 97.3-100%, respectively. Even with 25 mg, the sensitivity and specificity were both 100.0% at 20 min, and at the 5 min and 10 min time point, the EUBT yielded a sensitivity of 98.7% and a specificity of 100%. There was a significant positive correlation between the test values of the 5 min (13)C-EUBT with 25 mg of test urea and those of the conventional UBT. The 5 min EUBT with (13)C-urea offered high accuracy in the assessment of H. pylori eradication, with the sensitivity and specificity being 100% and 96.4%, respectively. In patients with previous gastrectomy, the EUBT provided acceptable accuracy (a sensitivity of 96.4% and a specificity of 97.0%).

CONCLUSIONS

Our results indicate that the (13)C-EUBT is an accurate method for detecting H. pylori infection. The EUBT using only 25 mg of (13)C-urea at the early (5 min) time point has satisfactory diagnostic efficacy in pre- and post-eradication treatment settings, providing a less expensive and more rapid way of performing the test. The EUBT may be a reliable method of assessing H. pylori status in the remnant stomach.

Diagnostic accuracy of the 13C-urea breath test for childhood Helicobacter pylori infection: a multicenter Japanese study

OBJECTIVES

In adults, the 13C-urea breath test (UBT) has been widely used as a noninvasive test of Helicobacter pylori infection because of its high sensitivity and specificity. However, this test is less well established in pediatric practice. The optimum cutoff value and test protocol of the 13C-UBT remains to be established in the pediatric population. The primary purpose of this study was to evaluate diagnostic accuracy of the 13C-UBT for children and to determine its optimum cutoff value.

METHODS

A total of 220 Japanese children aged 2-16 yr (mean = 11.9) who underwent upper GI endoscopy and gastric biopsies were finally studied. Endoscopic diagnoses included gastritis (n = 131), gastric ulcer (n = 15), duodenal ulcer (n = 72), and combined ulcer (n = 2). H. pylori infection status was confirmed by biopsy tests including histology, urease test, and culture. With the 13C-UBT, breath samples were obtained at baseline and at 20 min after ingestion of 13C-urea without a test meal and were analyzed by isotope ratio mass spectrometry. Based on biopsy tests, a cutoff value was determined using a receiver operating characteristic curve. In 26 children (seven children infected and 19 noninfected), paired breath samples were also measured by nondispersive infrared spectometry (NDIRS).

RESULTS

Biopsy tests demonstrated that 89 children (40%) were infected with H. pylori and 131 children were not infected. There were no statistical differences in mean delta 13C values at 20 min between male and female H. pylori-infected and noninfected patients. A receiver operating characteristic analysis defined the best cutoff value as 3.5 per thousand. The overall sensitivity and specificity at a cutoff value of 3.5 per thousand were 97.8% (95% CI = 92.1-99.7%) and 98.5% (95% CI = 96.4-100%), respectively: high sensitivity and specificity were demonstrated in all three age groups (< or =5, 6-10, and > or = 11 yr). There was a close correlation between the values with isotope ratio mass spectrometry and NDIRS methods (r = 0.998, p < 0.001).

CONCLUSIONS

The 13C-UBT with a cutoff value of 3.5 per thousand is an accurate diagnostic method for active H. pylori infection. The test with the NDIRS method is inexpensive and might be widely applied in clinical practice.

A quantitative evaluation of spurious results in the infrared spectroscopic measurement of CO2 isotope ratios

The possible generation of spurious results, arising from the application of infrared spectroscopic techniques to the measurement of carbon isotope ratios in breath, due to coincident absorption bands has been re-examined. An earlier investigation, which approached the problem qualitatively, fulfilled its aspirations in providing an unambiguous assurance that 13C16O2/12C16O2 ratios can be confidently measured for isotopic breath tests using instruments based on infrared absorption. Although this conclusion still stands, subsequent quantitative investigation has revealed an important exception that necessitates a strict adherence to sample collection protocol. The results show that concentrations and decay rates of the coincident breath trace compounds acetonitrile and carbon monoxide, found in the breath sample of a heavy smoker, can produce spurious results. Hence, findings from this investigation justify the concern that breath trace compounds present a risk to the accurate measurement of carbon isotope ratios in breath when using broadband, non-dispersive, ground state absorption infrared spectroscopy. It provides recommendations on the length of smoking abstention required to avoid generation of spurious results and also reaffirms, through quantitative argument, the validity of using infrared absorption spectroscopy to measure CO2 isotope ratios in breath.

Cut-off point, timing and pitfalls of the 13C-urea breath test as measured by infrared spectrometry

BACKGROUND

The best timing and the best cut-off level of the 13C-urea breath test have not yet been well established.

AIMS

To evaluate the cut-off value and the influence of medication on the 13C-urea breath test as measured by infrared spectrometry.

METHODS

A series of 223 patients, sent for endoscopy performed 13C-urea breath test in fasting conditions with 75 mg of 13C-urea and 20 ml of citric acid. Breath samples were collected before and then 10, 20, 25 and 30 minutes after ingestion. As gold standard, histological examination of gastric biopsies was used. A questionnaire was completed concerning the intake of medication, likely to influence the test, in the 2 months preceding the test. Sensitivity, specificity, positive predictive value and negative predictive value at 10, 20, 25 and 30 minutes at different cut-off values (3, 3. 5, 4, 4. 5, 5.0 0/00 DOB] were calculated.

RESULTS

A total of 182 patients did not take medication. There was no significant difference between the different cut-off levels at different times. Compared with the group of 41 patients who did take medication, likely to influence the test, the differences were significant (Fisher exact test).

CONCLUSION

There was no significant difference between the different cut-off values. A 10-minute test with a cut-off level between 4 and 5% delta over baseline (sensitivity: 100%, specificity: 95%) is, therefore, proposed. To avoid false negative results due to unknown intake of medication, every patient submitted to the 13C-urea breath test should fill out a questionnaire.