Appropriate cut-off value of 13C-urea breath test after eradication of Helicobacter pylori infection in Japan

BACKGROUND AND AIM: A cut-off value of 2.5 per thousand for the 13C-urea breath test (UBT) is recommended in Japanese persons, based on the result of a multicenter trial in patients prior to treatment for eradication of Helicobacter pylori. The cut-off value of 2.5 per thousand has also been used in the assessment of eradication after treatment. The 6-8-week evaluation after treatment is recommended in the guidelines of the Japanese Society of Gastroenterology. The present study aimed to prospectively re-assess the cut-off value of the 13C-UBT at 6 weeks after treatment by using the results obtained at 6 months as an indication of true positive or true negative H. pylori infection status. METHODS: One hundred and ninety patients who were positive for H. pylori underwent eradication treatment, and 177 patients of these patients who were assessed as having true positive or true negative H. pylori status at 6 months after treatment were evaluated in this study. Eradication was assessed by 13C-UBT, culture, and histology at 6 weeks and at 6 months after treatment, and the cut-off value of 13C-UBT at 6 weeks was re-assessed. RESULTS: A cut-off value of 3.5 per thousand. at 6 weeks after treatment showed 97.2% diagnostic accuracy, while a cut-off value of 2.5 per thousand at 6 weeks showed 96.0% diagnostic accuracy. For a 3.5 per thousand cut-off value, only five patients were positive by 13C-UBT and were negative by culture and histology at 6 weeks, and three patients were true positive and two were false positive by the 13C-UBT at 6 months. CONCLUSION: A cut-off value of 3.5 per thousand for the 13C-UBT is recommended at 6 weeks after eradication treatment in Japanese persons.     

Simplified 13C-urea breath test with a new infrared spectrometer for diagnosis of Helicobacter pylori infection

BACKGROUND AND AIM: Infrared spectrometry has correlated excellently with mass spectrometry in detecting the ratio of 13CO(2) to 12CO(2) in breath samples. The present study aimed to evaluate the accuracy of the 13C-urea breath test (13C-UBT) using a new model of infrared analyzer. METHODS: A total of 600 patients who were undergoing upper endoscopy without receiving eradication therapy were entered into the study. Culture, histology, and rapid urease test on biopsies from the antrum and corpus of the stomach were used for the determination of Helicobacter pylori infection. Breath samples were collected before and 20 min after drinking 100 mg 13C-urea in 100 mL water. The optimal cutoff value was determined by the receiver operating characteristic curve. RESULTS: Of the 586 patients who were eligible for analysis, 369 were positive for H. pylori infection, 185 were negative for H. pylori infection, and 32 were indeterminate. When the appropriate cutoff value was set at 3.5 per thousand, a sensitivity of 97.8%, a specificity of 96.8% and an accuracy of 97.5% were obtained using the 13C-UBT. The accuracy of the 13C-UBT decreased when CO(2) concentration in the breath sample was <2%, as compared with > or = 2% (93.6%vs 97.7%), mainly because of a decrease in specificity (81.8%vs 97.7%). There were 2.7% of patients with Delta13CO(2) values that fell between 3.0-4.5 per thousand, in whom the risk of error was 47%. CONCLUSIONS: The 13C-UBT performed with infrared spectrometry is a highly sensitive, specific, and non-invasive method for the detection of H. pylori infection. The immediate availability of the test result and technical simplicity make it particularly effective in routine clinical practice.     

Validation of the 13C-urea breath test for the diagnosis of Helicobacter pylori infection in children: a multicenter study

OBJECTIVE: The 13C-urea breath test (13C-UBT) is a safe, noninvasive, and accurate test for the detection of Helicobacter pylori (H. pylori) infection in adults. The aim of this study was to evaluate sensitivity and specificity of 13C-UBT in children using different types of test meal, doses of 13C-urea and breath sampling intervals. As yet, a validated, standardized 13C-UBT protocol for children has not been formulated. METHODS: 13C-UBT was performed in 115 children and repeated within 3 days, modifying the test meal or the dose of 13C-urea. H. pylori status was assessed by histology and rapid urease test. 13C-UBT was performed using 100 mg or 50 mg of 13C-urea and a fatty test meal (100 FA; 50 FA), 50 mg of 13C-urea, and a carbohydrate test meal (50 CA). Breath samples were collected every 10 min for 60 min. RESULTS: The 13C-UBT in children was highly sensitive and specific with all three protocols used. The best combination of sensitivity (97.92%) and specificity (97.96%) was obtained with Protocol 50 FA at 30 min with a cut-off of 3.5 per mil. CONCLUSIONS: The 13C-UBT is an accurate test for the detection of H. pylori infection also in children. Administration of 50 mg of 13C-urea, a fatty test meal, and breath sampling at 30 min appears to be the most convenient protocol.     

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.     

Validity of a Helicobacter pylori stool antigen assay for the assessment of H. pylori status following eradication therapy.

BACKGROUND: A Helicobacter pylori stool antigen (HpSA) test has been proposed as a valid alternative to the 13C-urea breath test (13C-UBT) for the non-invasive detection of H. pylori infection in primary diagnosis. Published reports show conflicting results with regard to the test's diagnostic accuracy after eradication therapy. The aim of the present study was to assess the diagnostic value of the HpSA test and to determine the optimal discriminating cut-off value in patients following H. pylori eradication therapy. METHOD: Stool samples were collected and the 13C-UBT was performed in 113 patients 4-6 weeks after eradication therapy. A validated test protocol for the 13C-UBT was used. Stool specimens were analysed with the Premier Platinum HpSA enzyme immunoassay (EIA). A receiver operator characteristics (ROC) analysis was performed to define the optimal cut-off value on the basis of the results of the 13C-UBT. RESULTS: The results of the 13C-UBT showed that H. pylori eradication was successful in 83/113 (73%) patients. According to the manufacturer, the cut-off value for the HpSA test is 0.14 optical density, but this does not appear to be valid after eradication therapy (sensitivity 76.7%, specificity 98.8%). On the basis of ROC analysis, the optimal cut-off value after therapy was determined to be 0.11 optical density, giving a sensitivity of 93.3% and a specificity of 93.9%. CONCLUSION: The HpSA test is a valid test for the assessment of H. pylori status after eradication therapy, provided an adjusted cut-off value is applied.     

Qualitative and quantitative clinical evaluation of the laser-assisted ratio analyser for detection of Helicobacter pylori infection by (13)C-urea breath tests

OBJECTIVES: Currently, the (13)C-urea breath test is the reference method for non-invasive diagnosis of Helicobacter pylori infection and therapy control. Therefore, new technologies have been developed to measure the ratio of (13)CO(2)/(12)CO(2) in breath. The laser-assisted ratio analyser (LARA) device is based on optogalvanic effects of the stimulated CO(2) molecules. DESIGN: In this study, the LARA system is prospectively compared to conventional isotope ratio mass spectrometry (IRMS) analysis of (13)C-urea breath tests. METHODS: The (13)C-urea breath test was used to screen 103 patients for H. pylori infection. Breath samples were analysed by LARA and IRMS techniques. RESULTS: Seven breath tests could not be analysed by the LARA system, one by IRMS. Out of the remaining 95 breath tests, 13 were positive for H. pylori infection (13.7%). In reference to IRMS analysis (with a cut-off of > 5 delta per thousand at 30 min), LARA produced one false positive and one false negative breath test result giving a sensitivity of 92.3% and a specificity of 98.8%. The mean difference in delta over baseline values between IRMS and LARA measurements was 2.02 delta per thousand +/- 5.48 delta per thousand. CONCLUSION: LARA allows the reliable qualitative evaluation of 13C-urea breath tests, but the quantitative results differ from IRMS findings.     

Delta (13)C-urea breath test value is a useful indicator for Helicobacter pylori eradication in patients with functional dyspepsia

BACKGROUND: Eradication of Helicobacter pylori is not routinely recommended for the symptomatic relief and the prevention of gastric cancer in patients with functional dyspepsia. The present study investigated a useful indicator of H. pylori eradication in such patients by determining the optimal cutoff value of a 13C-urea breath test (UBT). METHODS: One hundred dyspeptic patients participated in the study. Dyspepsia was scored, and a 13C-UBT administered. A level of delta 13C-UBT of>4 per thousand was diagnosed as H. pylori-positive. After the stomach was endoscopically sprayed with phenol red, biopsy specimens were taken from the antrum, body and cardia of the stomach for the assessment of H. pylori density, and activity (neutrophil infiltration) and degree (lymphocyte infiltration) of gastritis. RESULTS: Correlation between delta 13C-UBT and dyspepsia score was not found. Delta 13C-UBT significantly correlated with H. pylori density score in the total stomach (r = 0.53, P < 0.0001), neutrophil (r = 0.34, P = 0.0005) and lymphocyte score (r = 0.69, P < 0.0001). Twenty-six of the 100 subjects had a neutrophil score of >or=4, lymphocyte score of >or=4, and H. pylori score of >or=4. Their 95% confidence interval of mean was 58.2 per thousand, which reflects moderate to marked acute and chronic gastritis, and dense H. pylori colonization. CONCLUSIONS: The 13C-UBT is a reliable semiquantitative test to assess H. pylori density and the activity and degree of gastritis. It is proposed that H. pylori eradication therapy might be beneficial for patients with functional dyspepsia with a delta 13C-UBT of >58.2 per thousand.     

红外能谱仪检测~(13)C-尿素呼气试验诊断幽门螺杆菌感染

目的：验证红外能谱仪检测１３Ｃ－尿素呼气试验（ＵＢＴ）诊断幽门螺杆菌（Ｈ．ｐｙｌｏｒｉ）感染的可靠性,并与气体质谱仪检测结果作一比较。方法：对７６例患者以红外能谱仪进行１３Ｃ－ＵＢＴ检测Ｈ． ｐｙｌｏｒｉ感染,Ｈ． ｐｙｌｏｒｉ感染状态由快速尿素酶试验、组织学检查以及细菌培养确定。其中１７例患者的呼气样本分别用红外能谱仪与气体质谱仪进行检测。结果：７６例患者中Ｈ． ｐｙｌｏｒｉ阳性者４３例（５６．６％）,红外能谱仪进行１３Ｃ－ＵＢＴ的测定结果为４１例（５３．９％）,其敏感性和特异性分别达到９３．０％和９７．０％。气体质谱仪与红外能谱仪的检测数值相差无几。结论：以红外能谱仪进行１３Ｃ－ＵＢＴ检测可靠、准确地诊断Ｈ．ｐｙｌｏｒｉ感染,并具有简单、实用的特点。红外能谱仪与气体质谱仪一样可被广泛应用于Ｈ．ｐｙｌｏｒｉ检测。     

Validation of a simplified 13C-urea breath test method for the diagnosis of Helicobacter pylori infection]

OBJECTIVE: To validate a simplified 13C-urea breath test (13C-UBT) method for the diagnosis of H. pylori infection. MATERIAL AND METHODS: Patients referred for gastrointestinal endoscopy and biopsy were included, and a 13C-UBT was performed after a 6-hour fast. Breath samples were collected in 10 ml glass tubes before and 30 min after the simultaneous administration of 50 mg of 13C-urea and 2 g of citric acid in 200 ml of water. All breath samples were analyzed using isotope ratio mass spectrometry. The diagnosis of H. pylori infection was established with a positive culture and/or positive histology and serology. RESULTS: Eighty-eight patients were included, 49 female and 39 male with a mean age of 45 +/- 15 yrs. Fifty-one patients (57.95%) were positive and 30 (34.1%) negative for H. pylori. Seven cases (7.95%) were considered undetermined. The sensitivity, specificity, positive predictive value, and negative predictive value for 13C-UBT were 90.2, 93.3, 95.83, and 84.8%, respectively. Accuracy was 91.4%. CONCLUSIONS: The simultaneous administration of 50 mg of 13C-urea and 2 g of citric acid represents an alternative for the non-invasive diagnosis of H. pylori infection.     

Simplified 13C-urea breath test for the diagnosis of Helicobacter pylori infection--the availability of without fasting and without test meal

The conventional 13C-urea breath test (13C-UBT) for detecting Helicobacter pylori infection was performed during fasting state and with a test meal to delay gastric emptying during the test. For the convenience of propagating this test, we assessed the availability of non-fast and without test meal in 13C-UBT for the diagnosis of H. pylori infection. One hundred and five consecutive patients who received endoscopic examination were studied. All of them received endoscopic biopsy for urease test, culture and histopathology to determine whether there was a presence of H. pylori infection. Each patient received four separate 13C-UBT under the following four testing conditions. Test I) fasting state with test meal (100 ml fresh milk), Test II) non-fast (taking usual food) but with test meal, Test III) fasting state without test meal, and Test IV) non-fast and without test meal. The excess delta 13CO2 values were calculated via the breathed samples that were collected at 15 minutes after ingestion of 13C-urea. There were 61 H. pylori positive and 44 negative patients in this study, with an excess delta 13CO2 values 3.0, 4.0, 3.5 and 4.0 as a cut-off value in the four tests respectively, according to the ROC curve. The results of test I, a conventional procedure, had a good correlation with the gold standard. The sensitivity and specificity were 100% and 95% respectively. The alternative procedures in other tests also have high sensitivity and specificity at 15-minute detecting time. The sensitivity of the tests II, III and IV at 15-minute detecting times were 98%, 98% and 100%, and the specificities of those were 95%, 98% and 95% respectively. We therefore suggest that fasting and test meal possibly be omitted when the cut-off value is 4.0 per mil in the simplified 13C-UBT (non-fast and without test meal, and detection at 15 minutes after ingestion of 13C-urea) which is a simple and available procedure for clinical diagnosis of H. pylori infection.     

红外能谱测量法20mg酸化胶囊^13C-UBT的效能评价

目的探讨剂量小于常规75～100mg、红外能谱测量法^13C-尿素呼气试验（^13C-UBT）诊断幽门螺杆菌（H．pylori）感染的可行性。方法133例因消化不良进行胃镜检查的门诊患者,胃黏膜活检标本Giemsa染色检查H．pylori,红外能谱测量法进行20mg酸化胶囊^13C-UBT,分别应用ROC法和特异性优先法评价诊断效能。结果59例H．pylori阳性病人和74例阴性病人DOB值分别为5．27±4．49和-0．50±0．98,差异显著（P〈0．05）。ROC法的最适判别值为DOB=0．4时,其诊断敏感性、特异性和准确性分别为91．5％（54／59）、89．2％（66／74）和90．2％（120／133）;以特异性优先法的最适判别值为DOB=2．0时,其诊断敏感性、特异性和准确性分别86．4％（51／59）、100％（74／74）和94．0％（125／133）。结论红外能谱测量法小剂量^13C-尿素呼气试验是可行的,但20mg酸化胶囊^13C-尿素呼气试验方案尚不能满足临床诊断需要。     

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 rain 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.     

Evaluation of 13C-urea breath test to confirm eradication of Helicobacter pylori]

This study aimed to evaluate the effectiveness of the 13C-urea breath test (UBT) for assessment of Helicobacter pylori eradication after treatment. One hundred twenty six patients were enrolled with 85 receiving proton pomp inhibitor based triple therapy. They were underwent upper gastrointestinal endoscopy with biopsies for diagnosis and assessment of H. pylori infection using culture, histology, rapid urease test (RUT) and 13C-UBT. Assessment of eradication needs to be performed 4 weeks or more after completion of treatment. Breath samples were taken 15 minutes after the ingestion of 100 mg 13C-urea. Breath samples were analyzed on a mass spectrometer system. The gold standard for H. pylori infection was a positive culture or positive histology + positive RUT; negative for infection was defined as negative results of all three biopsy tests. Based on ROC curves, the most appropriate cut-off value for diagnosis of H. pylori infection was identified as 2.5/1000, which provided 96.2% sensitivity, 100% specificity, and 96.8% accuracy as judged by the gold standard. However, when confirming the eradication of H. pylori, it was 3.5/1000, which provides for 100%, 95.8%, and 96.5%, respectively. Ten patients (11.8%) had delta13C values that were 2.5-5.0/1000 4-12 weeks after therapy. Eight patients were considered cured of H. pylori infection, and 2 were considered to still have H. pylori infection following 13C-UBT, serology, and H. pylori specific antigen test. The false-positive rate of 13C-UBT was 9.4% (8/85). When the grey zone of 13C-UBT was set at a level of 2.5 to 5.0/1000 (2.5 > : negative, 5.0 < or = : positive) after eradication therapy, the sensitivity and specificity of 13C-UBT was 100% and 98.4% compared to the gold standard. It was concluded that to avoid false-positive results of 13C-UBT, the grey zone of 13C-UBT needs to be set at a level of 2.5 to 5.0/1000; thus improving the accuracy of test for the assessment of eradication of H. pylori infection.     

Studies of 13C-urea breath test for diagnosis of Helicobacter pylori infection in patients after partial gastrectomy

BACKGROUND/AIMS: Many of the reports on the diagnostic efficacy of the 13C-urea breath test (13C-UBT) for the detection of Helicobacter pylori in the residual stomach have shown negative results. We conducted an evaluation to establish a standardized protocol and an appropriate cutoff value for 13C-UBT in partial gastrectomy patients. METHODS: Forty-two patients undergoing partial gastrectomy were included. Three gastric biopsies from the anastomotic site and mid-to-high body were taken at panendoscopy for histology, culture and rapid urease test (RUT). The 13C-UBT protocol included ingestion of 100 mg 13C-urea, use of mouthwash, and the body in a horizontal position on the left side. Six breath samples were taken after ingestion. RESULTS: The Delta 13CO2 values were significantly elevated in infected patients at all time points, and values were higher at 20 min and thereafter than at an earlier time point. The sensitivity of 13C-UBT was 96.3% with the cutoff of 2.0 per thousand at 40 min. The accuracy rates were highest with 13C-UBT, culture, RUT and histological tests, in that order. CONCLUSION: Forty minutes and a cutoff of 2.0 per thousand were found to be optimal for the test, with the body position horizontal on the left side. In the present protocol 13C-UBT appears to be a reliable tool with the same accuracy rate as other routine tests in patients with a remnant stomach.     

Diagnosis of Helicobacter pylori gastritis in children using the 13C urea breath test

The clinical recognition of Helicobacter pylori gastritis in children with recurrent abdominal pain is difficult. We assessed the value of a simplified 13C urea breath test (13C-UBT) in a selected group of children with nocturnal waking and disruptive recurrent abdominal pain who fulfilled criteria for endoscopy. Gastric antral biopsies were examined histologically and by the quick urease test and were compared with H. pylori serology and the 13C-UBT in a prospective study of 50 children referred to a tertiary center. Thirty-two patients had gastritis and of these, 19 had histologically proven H. pylori gastritis. Seventeen of these 19 patients had a positive 13C-UBT. The sensitivity and specificity of the 13C-UBT compared with the histologic diagnosis of H. pylori was 89 and 90% respectively. The 13C-UBT was more specific than the H. pylori serology. The 13C-UBT using two breath collections is a reliable and noninvasive diagnostic test for H. pylori infection in children.     

Quantification of Helicobacter pylori infection: Simple and rapid 13C-urea breath test in Taiwan

The ¹³C-urea breath test (¹³C-UBT) is a non-invasive method for detecting Helicobacter pylori. This study was performed to determine the cutoff value and evaluate the sensitivity and specificity of ¹³C-UBT in Taiwan. ¹³C-Urea (100 mg of 99% ¹³C-labeled urea) was dissolved in 50 ml sterile water for the test. The test meal for delaying gastric emptying was 100 ml fresh milk. Patients fasted for at least 6 h. A baseline breath sample was collected 5 min after they had the test meal. Two other samples were collected at 15 and 30 min after the patients ingested the ¹³C-urea. The test was evaluated in 352 patients after routine upper gastrointestinal endoscopy, and the urease test, culture, and histopathology were taken as the gold standards for detecting H. pylori. According to the receiver operating characteristic (ROC) curves, we chose values of 2.8 and 4.2 excess δ¹³CO₂ per mil as the cut-off values for 15 and 30 min, respectively, post ¹³C-urea. The sensitivity and specificity of ¹³C-UBT were 99% and 93% at 15 min, and 98% and 93% at 30 min post ¹³C-urea, respectively. The ¹³C-UBT breath test is an efficient non-invasive method of high sensitivity and high specificity for detecting H. pylori infection. We suggest that the use of fresh milk as the test meal and the detection of excess δ¹³CO₂ 15 min after the ingestion of ¹³C-urea are suitable for the clinical use of ¹³C-UBT. This test is simple and rapid. (Received June 18, 1997; accepted Oct. 30, 1997)     

Endoscopic 13C-urea breath test for detection of Helicobacter pylori infection after partial gastrectomy

BACKGROUND/AIMS: It is difficult to interpret the results of 13C-urea breath test (UBT) in gastrectomy patients because the test urea may pass through the stomach faster. The aim of this study is to evaluate the efficacy of the modified endoscopic UBT for detection of Helicobacter pylori (H. pylori) infection in the residual stomach. METHODOLOGY: An endoscopic UBT was performed in 44 patients who had undergone partial gastrectomy. At endoscopy, 20 mL of water containing 100mg of 13C-urea were sprayed onto the gastric mucosa and an intragastric gas sample was immediately collected through the biopsy channel. Breath samples were collected at 20 min after spraying 13C-urea. RESULTS: The intragastric delta13CO2 value in H. pylori-positive patients was significantly higher than those of 20-minute breath samples. The maximum sensitivity and specificity of intragastric samples were 97% and 100% with cutoff point of 5 per thousand, respectively. The sensitivity and specificity of breath samples at 20 min were 71.4% and 66.7% with cutoff point of 0.6 per thousand, respectively. CONCLUSIONS: An endoscopic UBT was superior to a standard UBT to detect H. pylori infection after partial gastrectomy.     

Validity of a modified 13C-urea breath test for pre- and posttreatment diagnosis of Helicobacter pylori infection in the routine clinical setting

OBJECTIVE: Citric acid meets the criteria of an optimal test drink for the 13C-urea breath test (13C-UBT) because it permits rapid, high level recovery of the 13C administered. In a previous study we reported that administration of 13C-urea dissolved in a citric acid solution provides results similar to those obtained with standard administration of the substrate 10 min after the test drink. The aim of this study was to evaluate the accuracy of this modified 13C-UBT for both primary and posttreatment diagnosis of Helicobacter pylori (H. pylori) infection in a large patient population in clinical practice. METHODS: The 13C-UBT was performed in 553 patients with dyspeptic symptoms by giving them 75 mg of 13C-urea either 10 min after administration of 200 ml of a test drink comprising 0.1 mol/L citric acid solution (protocol 1, n = 320) or dissolved in the same amount of this test drink (protocol 2, n = 233). All patients underwent an upper gastrointestinal endoscopy and the H. pylori-status was assessed by histology, rapid urease test, and culture. Sixty patients with proven H. pylori infection were reinvestigated by both endoscopy and 13C-UBT (protocol 2) 4 wk after completing eradication therapy. RESULTS: The accuracy of the two test protocols in the pretreatment diagnosis of H. pylori infection (95.6% and 96.6%), as well as of the modified 13C-UBT in the posttreatment evaluation of the infection (98.3%) was similar. More meaningful are the high PPV (>96%) and NPV (>93%) of the 13C-UBT under pre- and posttreatment conditions. CONCLUSIONS: The administration of 13C-urea dissolved in a citric acid solution simplifies the 13C-UBT, while preserving the high accuracy in the diagnosis of H. pylori infection. This modified 13C-UBT has equal accuracy in the pre- and the posttreatment situations.     

Quantitative correlation of Helicobacter pylori stool antigen (HpSA) test with 13C-urea breath test (13C-UBT) by the updated Sydney grading system of gastritis

BACKGROUND/AIMS: Helicobacter pylori (H. pylori) infection has a causative relationship with various gastrointestinal disorders. 13C-urea breath test and H. pylori stool antigen test are two valuable noninvasive tests for detecting H. pylori infection. Since the bacterial load of H. pylori in the stomach and the resulting severity of gastritis are important in validating the status of H. pylori infection, we would like to investigate the relative diagnostic accuracy of 13C-urea breath test and H. pylori stool antigen test with respect to the severity of gastritis. METHODOLOGY: The H. pylori statuses of 62 consecutive patients were evaluated by five tests, i.e., culture, histology, biopsy urease test, 13C-urea breath test, and H. pylori stool antigen test. Gastritis was graded by the updated Sydney system. H. pylori status was defined as positive when the culture was positive or the concordance of positivity of two of the other four tests. RESULTS: Thirty-five patients (56%) were H. pylori positive. The accuracy of H. pylori stool antigen test and 13C-urea breath test were 92.6% and 100%, respectively. There was a positive correlation between the level of delta 13CO2 of the 13C-urea breath test and the optical density value of enzyme immunoassay of the H. pylori stool antigen test (Rho = 0.758, P < 0.001). Both the level of delta 13CO2 of 13C-UBT and the optical density value of enzyme immunoassay of the H. pylori stool antigen test correlated well with the separate score of the density of H. pylori (P < 0.001, each) and the inflammatory activity (each P < 0.001). CONCLUSIONS: Both the 13C-urea breath test and H. pylori stool antigen test are effective non-invasive methods to detect the status of H. pylori infection with respect to correlation with the density of H. pylori and inflammatory activity of gastritis.     

The diagnostic validity of Helicobacter pylori stool antigen test in the pre- and post-eradication]

BACKGROUND/AIMS: The efficacy of a new enzyme immunoassay designed to detect H. pylori antigens in stool (HpSA) was evaluated before and after the eradication therapy. METHODS: HpSA test was performed in 75 patients whose H. pylori status was defined on the basis of concordant results of the 13C-urea breath test (13C-UBT), rapid urease test and histology. Fifty-one H. pylori-positive patients were treated with a week regimen of triple therapy (amoxicillin 1.0 g b.d., clarithromycin 500 mg b.d., rabeprazole 10 mg b.d). Four weeks after the completion of therapy, previous tests including HpSA were repeated on 29 of 51 patients. Six weeks after the completion of therapy, HpSA test was repeated on 10 of 29 patients. RESULTS: Before the eradication, the sensitivity, specificity, and accuracy of HpSA test was 80.4%, 95.2% and 84.7%, respectively. When the cut-off value of 0.12 was adopted on the basis of our receiver operation characteristics (ROC) curve, the sensitivity and specificity improved as 90.0% and 95.2%. Four weeks after the completion of therapy, the sensitivity, specificity and accuracy of HpSA test was 50.0%, 88.9% and 86.2%, respectively. In 3 patients, false positive results at 4th week were converted to true negative at 6 weeks. CONCLUSIONS: The HpSA test is a useful diagnostic method for H. pylori in pre-eradication stage. The specificity of HpSA test in the post-eradication was similar to other studies. For the velue of HpSA test in the post-eradication period, further studies about the cut-off value and the guideline of optimal time after the eradication may be needed.