14C-urea breath test in patients undergoing anti-tuberculosis therapy

AIM: Urea breath test (UBT) is a non-invasive diagnostic test for detecting the presence of Helicobacterpylori(H pylori). In this study we evaluated the effect of anti-tuberculosis therapy on the results of 14C-UBT. METHODS: Patients, with the diagnosis of tuberculosis (TB) who had a positive UBT at the point of starting anti-TB therapy, were included. None had a history of peptic ulcer disease or had taken antibiotics, bismuth compounds and/or PPI in the previous month. 14C-UBT was repeated at the end of the second month and the end of treatment period and one month after completion of treatment course. RESULTS: Thirty-five patients (23 males) were enrolled. 14C-UBT was negative in all 35 patients (100%) at the end of the second month and remained negative in 30 cases (85.7%) at the end of the treatment course. One month after completion of treatment course, UBT remained negative in 13 patients (37.1%). CONCLUSION: Our report underscores the need for caution while interpreting urea breath test results in patients undergoing anti-TB therapy. Furthermore, the combination of drugs used in this study resulted in H pylori eradication in a minority of patients.     

14C-urea breath test for assessment of gastric Helicobacter pylori colonization and eradication.

BACKGROUND AND OBJECTIVE: Urea breath test (UBT) is a reliable noninvasive technique for detecting gastric Helicobacter pylori colonization. 14C isotope-based test requires simple equipment and is inexpensive. We studied the utility of 14C-UBT in diagnosis of gastric H. pylori infection. METHODS: Presence of H. pylori was studied using antral histology and culture in patients with rapid urease test (RUT)-positive peptic ulcer. 14C-UBT was performed using a 185-kBq dose. Radioactivity in 15-min breath samples was measured using a beta-scintillation counter and result expressed as % dose recovered/mmol CO2. H. pylori was considered positive when any two tests were positive. All tests were repeated one month after completion of H. pylori eradication therapy. RESULTS: Among 41 patients (duodenal ulcer 36, gastric ulcer 5), H. pylori was detected by histology in 23 (56%) and by culture in 27 (66%). Overall, H. pylori was detected in 28 (68%) patients. Follow-up assessment was possible in 28 patients: 26 cleared the infection (all three tests negative). Mean 14C recovery values at 15 minutes associated with H. pylori-positive status were significantly higher (12.3 [SD 6.8] x 10(-3); n=30; p<0.001) than those associated with H. pylori-negative status (2.1 [0.9] x 10(-3); n=26). Using receiver-operating-characteristic analysis of 15-minute 14C recovery values, a cut-off of 6.5x10(-3) gave the best separation of H. pylori-positive and -negative cases. 14C-UBT had 93% sensitivity, 96% specificity and 95% accuracy. CONCLUSION: 14C-UBT appears to be a reliable noninvasive test for diagnosis of H. pylori infection.     

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。     

Changes in gastric environment with test meals affect the performance of 14C-urea breath test

BACKGROUND: (14)C-urea breath test (UBT) is considered to be an accurate diagnostic test for the detection of active Helicobacter pylori infection. Various test meals are used in (14)C-UBT to slow down gastric emptying, and to enhance the gastric distribution, in order to increase the time and area of contact between microorganisms and the tracer substrate. The aim of the present paper was to evaluate the effect of gastric environment on the performance of (14)C-UBT using an alkaline and an acidic liquid test meal having gastric emptying retardant effect. METHODS: The comparison of (14)C-UBT was done with liquid test meals (200 mL water) comprising (i) plain drinking water (PDW); (ii) 1.3 g or 3.0 g citric acid (CA); and (iii) 3.0 g trisodium citrate (TSC). Eighteen patients (37 +/- 12 years, range 18-57 years) with complaints of dyspepsia participated in the study. The status of H. pylori was confirmed by histology and rapid urease test. A total of 93 kBq of (14)C-urea (0.5 mL) in a gelatin capsule was orally administered along with liquid test meals to the overnight fasting subjects. Breath samples were collected and radioactivity measured. Results were expressed as (14)CO(2)/mmol exhaled CO(2) as percentage of administered radioactive urea. RESULTS: Higher acidic gastric environment (pH approx. 2.0) with CA was found to increase the exhaled (14)CO(2) level in a dose-dependent manner as compared to PDW and TSC meal (P < 0.05) at all time points. With TSC test meal, the expired (14)CO(2) level decreased in the lower acidic gastric environment (pH approx. 5.3). The peaks of exhaled (14)CO(2) with TSC test meal were observed at the same time points as that with PDW and CA test meals. The (14)C-UBT with TSC was found to be positive in 77% of patients (10/13). CONCLUSION: Better interaction between the microbial urease and (14)C-urea, caused by a test meal that retards gastric emptying and that changes gastric pH, plays an important role in hydrolysis of the administered (14)C-urea by H. pylori urease.     

~(13)C-尿素呼气试验诊断幽门螺杆菌感染的研究

本研究旨在评估~(13)C,尿素呼气试验检测幽门螺杆菌感染的可靠性。方法:我们在82例因胃病而行胃镜检查的患者胃窦和胃体取多个活检标本,作组织学、牯膜涂片和快速尿素酶试验,以决定是否感染幽门螺杆菌,并作~(13)C-尿素呼气试验。~(13)C-尿素呼气试验的敏感性、特异性、阳性预测值、阴性预测值是与组织学和尿素酶方法检测幽门螺杆菌的结果比较而计算得到。结果:~(13)C-尿素呼气试验的敏感性97.92％,特异性100％,阳性预测值100％,阴性预测值97.14％,准确性98.78％。结论:~(13)C-尿素呼气试验有高度敏感性和特异性,对确定患者的幽门螺杆菌感染状态是一可靠的无创伤的诊断方法。     

Test and treat strategies for Helicobacter pylori in uninvestigated dyspepsia: a Canadian economic analysis.

BACKGROUND: Recognition of the pivotal role of Helicobacter pylori in the pathogenesis of peptic ulcer disease has revolutionized primary care approaches to dyspepsia. Decision analysis was used to compare the cost effectiveness of empirical ranitidine with a test and treat strategy using either H pylori serology or the 13carbon-urea breath test (13C-UBT). PATIENTS AND METHODS: A cohort of patients under age 50 years presenting with uninvestigated dyspepsia was evaluated. Three initial strategies were compared with respect to direct medical costs and effectiveness in curing H pylori-related ulcers - empirical ranitidine, H pylori serology and UBT. A one-year time horizon and third-party payer perspective were adopted in a Canadian health care setting. RESULTS: UBT was more costly than either serology or ranitidine but was the most effective strategy and required the fewest endoscopies. No strategy demonstrated dominance over another in the base case. The incremental cost effectiveness ratio (ICER) of serology versus ranitidine was $118/cure, and sensitivity analysis induced dominance of serology in several plausible scenarios. The baseline ICER of UBT versus serology was $885/cure but showed substantial variation in sensitivity analysis. Each ICER was highly sensitive to variation in the cost of the tests themselves. At a serology cost of $25, UBT became dominant when its cost fell to $39. CONCLUSIONS: In low risk patients with uninvestigated dyspepsia, testing for H pylori using serology appears to be economically attractive. 13C-UBT may be a cost effective alternative to serology if local conditions closely approximate the model parameters. Future changes in the costs of serology and 13C-UBT may determine the optimal approach.     

^13C—尿素呼气试验诊断幽门螺杆菌感染的研究

目的评估13C-尿素呼气试验（13C-UBT）幽门螺杆菌（Hp）感染的可靠性。方法对82例因胃病而行胃镜检查的患者，于胃窦和胃体取多个活检标本作组织学、粘膜涂片和快速尿素酶试验，以决定是否感染Hp，并作13C-UBT。结果13C-UBT的敏感性、特异性、阳性预测值、阴性预测值是与组织学和尿素酶方法检测Hp的检测结果比较而计算得到。13C-尿素呼气试验的敏感性97．92％、特异性100％、阳性预测值100％、阴性预测值97．14％、准确性98．78％。结论13C-尿素呼气试验有高度敏感性和特异性，对确定患者的Hp感染状态是一非常可靠而又无创伤的诊断方法。     

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.     

Carbon urea breath test is not as accurate as endoscopy to detect Helicobacter pylori after gastrectomy

BACKGROUND: This study was conducted to determine (1) whether Helicobacter pylori infection decreases in conjunction with time elapsed after gastrectomy and (2) the diagnostic efficacy of (13)C urea breath test (UBT) for H pylori in patients after gastrectomy. METHODS: From January 1997 to June 1998, 86 patients who had undergone gastrectomy and 180 patients with dyspepsia without gastrectomy were enrolled. A UBT for the analysis of excess (13)CO(2)/(12)CO(2) ratio (ECR) was obtained for each patient. Each patient also underwent endoscopy to obtain gastric biopsies for histology and H pylori culture. The presence of H pylori by either histology or culture served as the standard to test the efficacy of UBT. The 86 patients with a prior gastrectomy were categorized into 3 subgroups (I, less than 1 year; II, 1 to 3 years; III, greater than 3 years), according to the interval between surgery and UBT. The initial H pylori status of these 86 patients was determined by histologic evaluation of the resected stomach. RESULTS: At trial initiation, the postgastrectomy group had a lower H pylori infection rate (52.3%) as compared with the dyspeptic control group (80%). The initial H pylori status among subgroups I, II, and III was similar. There was a trend for the presence of H pylori in the stomach to decrease with increasing time elapsed after surgery (I to III: 68.8%, 48.3%, 36%, respectively; p < 0.05). The maximum UBT sensitivity and specificity achieved were 82.2% and 87.8% in the gastrectomy group and 97.2% and 96.3% in the dyspeptic group, with cutoff points of 2.5 and 4.0, respectively. CONCLUSION: The prevalence of H pylori diminishes with time elapsed after gastrectomy. UBT for detection of H pylori is more effective in patients without prior gastrectomy than in patients who have undergone gastrectomy and is less effective than endoscopy for patients who have had a gastrectomy.     

14C尿素呼气试验检测幽门螺杆菌感染在老年人疾病诊断中的应用探讨

目的探讨14C尿素呼气试验(urea breath test,UBT)检测幽门螺杆菌(H.pylori)感染在老年人消化道疾病、急性冠脉综合征(ACS)诊断中的意义.方法用自身对照的方法比较30例消化道疾病患者内镜活检快速尿素酶试验H.pylori阳性与UBT阳性、血清学阳性情况,20例血清学H.pylori抗体阳性的ACS患者与UBT、内镜阳性情况.结果消化道疾病组内镜活检H.pylori阳性者做UBT的阳性率为93%,血清学阳性95%,血清学H.pylori阳性的ACS者做UBT的阳性率为50%,不稳定心绞痛者症状消失10 d后查内镜H.pylori阳性率为42%.结论用UBT诊断老年人与H.pylori感染有关的疾病安全可靠.     

13C-尿素呼气试验在蒙古沙鼠幽门螺杆菌感染检测中的应用

目的　应用13 C -尿素呼气试验检测蒙古沙鼠幽门螺杆菌感染 ,从而建立一长期监控小型试验动物幽门螺杆菌感染无创检测技术。方法　分别在蒙古沙鼠感染幽门螺杆菌后第 2 0 ,5 0 ,10 0及 2 0 0d用13 C -尿素呼气试验进行检测 ,并对检测后沙鼠以细菌分离培养、ELISA、PCR、快速尿素酶试验、病理切片等五种常规方法检测幽门螺杆菌。结果　在上述不同检测时期 ,用13 C -尿素呼气试验所得蒙古沙鼠幽门螺杆菌感染阳性率分别为 77 78% ,83 33% ,84 2 1%和 80 0 0 % ,而应用常规方法检测结果阳性率为 83 33% ,88 88% ,94 2 1%和 85 0 0 %。比较两组试验结果发现 ,13 C -尿素呼气试验比常规检测方法检出阳性率相对偏低 ,但统计学分析发现其具有一致性。结论　13 C -尿素呼气试验用于幽门螺杆菌感染蒙古沙鼠模型检测是一种可行的无创检测方法 ,可作为评价Hp感染的重要参考指标之一     

A combination of the Helicobacter pylori stool antigen test and urea breath test is useful for clinical evaluation of eradication therapy: a multicenter study

BACKGROUND: Helicobacter pylori stool antigen (HpSA) test is a new tool for evaluating the H. pylori infection. The present study was carried out to investigate the clinical usefulness of the HpSA test in the evaluation of eradication therapy by comparing it with the (13)C-urea breath test (UBT). METHODS: One hundred and five patients received eradication therapy for H. pylori. After more than 8 weeks, the success of the therapy was evaluated by the HpSA test and the UBT. Concordant results were regarded as a final diagnosis, but when the results were discordant, histological examination was carried out. RESULTS: Of the 105 patients receiving eradication therapy for H. pylori, 25 patients were regarded as H. pylori positive by the UBT and and 20 patients were regarded as H. pylori positive by the the HpSA test. Nine patients (8.6%) showed discordant results (seven cases with UBT(+) and HpSA(-), and two with UBT(-) and HpSA(+)). Five cases out of nine were ultimately judged as having a false-positive result of the UBT, and in these cases the UBT values were relatively low (below 10 per thousand). The final diagnostic accuracies of the UBT and the HpSA test were 94.3% (88.0-97.9%; 95% CI) and 97.1% (91.9-99.4%), respectively. When we used the HpSA test in cases with weakly positive UBT values, we were able to diagnose the correct status of H. pylori infection after eradication in 99% of all patients (94.8-100.0%). CONCLUSION: The HpSA test is a useful tool for the evaluation of eradication therapy and a combination of the HpSA test and UBT is clinically recommended.     

Influence of urease activity of the oral cavity and oropharynx on 13C-urea breath test]

We examined whether 13C-urea breath test with powdered 13C-Urea is affected with urease activity in the oral cavity and oropharynx in H. pylori negative cases. We also examined whether the degree of gargling affects the results of 13C-UBT. The results demonstrated that the urease activity not only in the oral cavity, but in the oropharynx may influence the UBT value. Therefore, it is possible that the UBT value may be affected with relic urease activity in the oropharynx if only the oral cavity is gargled. In conclusion, Gargling of the oropharynx in addition to the oral cavity is important to obtain true negative diagnosis with 13C-UBT in patients without Helicobacter pylori infection.     

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.     

Comparison of a monoclonal antigen stool test （Hp STAR） with the ^13C-urea breath test in monitoring Helicobacter pylori eradication therapy

AIM: To evaluate the agreement between a mAb-based stool test (HP StAR) and the urea breath test (UBT) in monitoring (H pylori) infection after eradication therapy. METHODS: Patients with discordant results on UBT and Hp StAR underwent endoscopy with biopsies for rapid urease test, culture, and histology to confirm H pylori status. RESULTS: Among 250 patients (50±14 years), 240 (96.0%) had concordant UBT and Hp StAR tests with a significant correlation between DOB and 4 values (R=0.87; P<0.0001). The remaining 10 (4.0%) patients had discordant tests (positive Hp StAR and negative UBT) with the Hp StAR inaccurate in five cases (false positive) and UBT inaccurate in the other five cases (false negative). The "maximal expected" sensitivity, specificity, +PV, -PV, +LR, and -LR were 91%, 100%, 100%, 97.4%,∞, and 8.2 respectively, for the UBT, and 100%, 97.4%, 91%, 100%, 38.8, and 0, respectively, for the Hp StAR. Overall accuracy for both tests was 98%. CONCLUSION: Both the UBT and the Hp StAR are equally accurate in monitoring H pylori infection. Nowadays, the choice of the "best" non-invasive H pylori test in the post-treatment setting should be done not only in terms of diagnostic accuracy but also in view of cost and local facilities.     

Influence of lansoprazole,famotidine, roxatidine and rebamipide administration on the urea breath test for the diagnosis of Helicobacter pylori infection

BACKGROUND AND AIM: The sensitivity of the urea breath test (UBT) has been reported to be influenced by the administration of omeprazole, lansoprazole and ranitidine. However, it is unclear whether other H2 receptor antagonists (H2RA), except ranitidine, and rebamipide, a mucosal protective agent, affect UBT sensitivity. The aim of this study is to clarify the effects of lansoprazole, famotidine, roxatidine and rebamipide administration on UBT sensitivity. METHODS: Subjects comprised 30 volunteers with Helicobacter pylori infection. All subjects were examined by the 13C-UBT on four occasions: (i) without medication (control); (ii) after the administration of 30 mg lansoprazole (u.i.d) for 14 days; (iii) after the administration of 100 mg rebamipide (t.i.d) for 14 days; and (iv) after the administration of 20 mg famotidine or 75 mg roxatidine (b.i.d) for 14 days. In the H2RA study, individuals were randomized into two groups of 15 subjects and were administered either famotidine or roxatidine. RESULTS: Five of the 30 cases administered lansoprazole and one of the 15 cases given roxatidine gave a false-negative UBT result. No negative UBT results were observed in patients administered famotidine or rebamipide. CONCLUSION: Patients showing negative UBT results during the administration of proton pump inhibitors and H2RA should be re-examined after the cessation of these drugs to confirm the true negativity of H. pylori infection.     

Urea breath test for Helicobacter pylori detection: present status.

Helicobacter pylori (H. pylori) is the commonest bacterial pathogen found worldwide and more than half the world population aged 40 years and above is colonized with it. The infection rate is >95 % in some African countries. In 1994, the International Agency for Research on cancer classified H. pylori as a class I carcinogen in humans. It causes chronic active gastritis, duodenal and gastric ulcer and gastric malignancy, and is thought to be associated with coronary artery disease, cerebral stroke, vitamin B12 and iron-deficiency anaemia, etc. Therefore, non-invasive test-and-treatment strategies are widely recommended in primary care settings. Conventionally, H. pylori infection can be diagnosed by invasive techniques using an upper gastrointestinal endoscope for obtaining multiple biopsies from different sites of the stomach for RUT, culture, histological examination, polymerase chain reaction (PCR), etc. and by non-invasive tests such as Urea breath test (UBT), stool antigen test and blood serology. At present, 13/14C-UBT is considered the test of choice for confirmation of H. pylori infection. The UBT is based on the principle, that isotopically labelled urea ingested by an H. pylori--infected patient is rapidly hydrolysed by the microbial urease. The released 13/14CO2 is absorbed across the mucous layer to the gastric mucosa and hence, excreted via the systemic circulation in the breath which is collected and measured. The non-hydrolysed urea is excreted completely in the urine within 3-4 days. 13C-UBT being non-radioactive, 13C-UBT can be used in pregnant women and children, and a user's license is not required. There is still no standard protocol accepted and followed internationally for this test. Although the methods are almost similar, various laboratories/clinics use variable tracer doses, test meals, timings and methods for breath collection, and different cut-off values, which make formal validation studies necessary. This review describes the present status of the UBT and its application in the detection of H. pylori infection.     

~(14)C-呼气试验检测幽门螺杆菌感染

本文应用国产~(14)C-呼气试验(~(14)C-UBT)试剂检测幽门螺杆菌(Hp)。同时应用病理组织染色、尿素酶试验、细菌培养和血清 ELISA 技术等方法与之进行比较。117例病人中 Hp 阳性率为47.9%(56/117),~(14)C-UBT的敏感性与特异性分别为94.6%和93.4%。~(14)C-UBT 由于相对于胃镜依赖的方法而言创伤性大大降低,是目前检测 Hp 感染,尤其是药物治疗后复查时的首选方法。     

Appropriate timing of the 14C-urea breath test to establish eradication of Helicobacter pylori infection

OBJECTIVE: The aim of this study was to determine the performance characteristics of the 14C-urea breath test (UBT) performed 2 wk after the completion of therapy for Helicobacter pylori using a 4 to 6 wk study as the gold standard. METHODS: Patients with active Helicobacter pylori infection at four medical centers received proton pump inhibitor-based triple or quadruple therapy for 10-14 days. Patients underwent the 14C-UBT 2 and 4-6 wk after the completion of therapy. A positive test was defined as 14CO2 excretion of >200 dpm, a negative test as <50 dpm, and an equivocal test as >50 but <200 dpm. Performance characteristics of the 2-wk UBT were calculated using the 4 to 6-wk result as a gold standard. RESULTS: Eighty-five patients were enrolled and 82 patients (mean +/- SD age, 62 +/- 15 yr; 15 women) completed the protocol. Four patients had equivocal UBT results and were excluded from the analysis. Of the 78 patients, 68 (87%) had a negative 4 to 6-wk UBT. The 2-week UBT yielded a sensitivity of 90% (95% confidence interval 72-100%), specificity of 99% (97-100%), and accuracy of 97% (93-100%). In patients with a persistently positive UBT, 14CO2 excretion at 2 wk was significantly lower than at 4-6 wk after therapy (p = 0.03). CONCLUSIONS: A UBT performed 2 wk after therapy yielded results comparable to 4 to 6 wk testing. Further studies to evaluate the optimal time of confirmatory testing in the age of more effective proton pump inhibitor-based triple therapies are warranted.     

Validity and cost comparison of 14carbon urea breath test for diagnosis of H Pylori in dyspeptic patients

AIM: To validate and compare the cost of microdose 14C urea breath test (UBT) with histology and rapid urease test for the diagnosis of H Pylori. METHODS: Ninety-four consecutive patients with dyspeptic symptoms undergoing gastroscopy were enrolled. Gastric biopsies were taken for histology and rapid urease test. UBT was performed after gastroscopy by microdose 14C urea capsules. Sensitivity, specificity and accuracy of UBT were calculated and compared with histology and rapid urease test. Cost comparison of these tests was also performed. RESULTS: H pylori was diagnosed by histology and rapid urease test in 66 (70%) and 61 (65%) patients, while 14C UBT detected infection in 63 (67%). Accuracy of UBT was 93% in comparison with histology while its positive and negative predictive values were 97% and 84%, respectively. Comparison of 14C UBT with rapid urease test gives an accuracy of 96%, with positive and negative predictive values of 95% and 97%, respectively. These results were highly reproducible with a Kappa test (P value<0.001). Cost of histology or rapid urease test with gastroscopy was 110 USD or 95 USD respectively while the cost of UBT was 15 USD. CONCLUSION: Microdose 14C UBT was comparable to histology and rapid urease test. 14C UBT is an economical, self sufficient and suitable test to diagnose active H pylori infection in less developed countries.