Breath tests and irritable bowel syndrome

Breath tests are non-invasive tests and can detect H2 and CH4 gases which are produced by bacterial fermentation of unabsorbed intestinal carbohydrate and are excreted in the breath. These tests are used in the diagnosis of carbohydrate malabsorption, small intestinal bacterial overgrowth, and for measuring the orocecal transit time. Malabsorption of carbohydrates is a key trigger of irritable bowel syndrome (IBS)-type symptoms such as diarrhea and/or constipation, bloating, excess flatulence, headaches and lack of energy. Abdominal bloating is a common nonspecific symptom which can negatively impact quality of life. It may reflect dietary imbalance, such as excess fiber intake, or may be a manifestation of IBS. However, bloating may also represent small intestinal bacterial overgrowth. Patients with persistent symptoms of abdominal bloating and distension despite dietary interventions should be referred for H2 breath testing to determine the presence or absence of bacterial overgrowth. If bacterial overgrowth is identified, patients are typically treated with antibiotics. Evaluation of IBS generally includes testing of other disorders that cause similar symptoms. Carbohydrate malabsorption (lactose, fructose, sorbitol) can cause abdominal fullness, bloating, nausea, abdominal pain, flatulence, and diarrhea, which are similar to the symptoms of IBS. However, it is unclear if these digestive disorders contribute to or cause the symptoms of IBS. Research studies show that a proper diagnosis and effective dietary intervention significantly reduces the severity and frequency of gastrointestinal symptoms in IBS. Thus, diagnosis of malabsorption of these carbohydrates in IBS using a breath test is very important to guide the clinician in the proper treatment of IBS patients.

Measurement of hepatic functional mass by means of ^(13)C-methacetin and ^(13)C-phenylalanine breath tests in chronic liver disease: Comparison with Child-Pugh score and serum bile acid levels

AIM: To evaluate and compare the clinical usefulness of 13C-phenylalanine and 13C-methacetin breath tests in quantitating functional hepatic mass in patients with chronic liver disease and to further compare these results with those of conventional tests, Child-Pugh score and serum bile acid levels.METHODS: One hundred and forty patients (50 HCV-related chronic hepatitis, 90 liver cirrhosis patients) and 40 matched healthy controls were studied. Both breath test and routine liver test, serum levels of cholic and chenodeoxycholic acid conjugates were evaluated.RESULTS: Methacetin breath test, expressed as 60 min cumulative percent of oxidation, discriminated the hepatic functional capacity not only between controls and liver disease patients, but also between different categories of chronic liver disease patients. Methacetin breath test was correlated with liver function tests and serum bile acids.Furthermore, methacetin breath test, as well as serum bile acids, were highly predictive of Child-Pugh scores. The diagnostic power of phenylalanine breath test was always less than that of methacetin breath test.CONCLUSION: Methacetin breath test represents a safe and accurate diagnostic tool in the evaluation of hepatic functional mass in chronic liver disease patients.

Evaluation of urea breath test as a diagnostic tool for Helicobacter pylori infection in adult dyspeptic patients

In this editorial,we discuss the article in the World Journal of Gastroenterology.The article conducts a meta-analysis of the diagnostic accuracy of the urea breath test(UBT),a non-invasive method for detecting Helicobacter pylori(H.pylori)infection in humans.It is based on radionuclide-labeled urea.Various methods,both invasive and non-invasive,are available for diagnosing H.pylori infection,inclu-ding endoscopy with biopsy,serology for immunoglobulin titers,stool antigen analysis,and UBT.Several guidelines recommend UBTs as the primary choice for diagnosing H.pylori infection and for reexamining after eradication therapy.It is used to be the first choice non-invasive test due to their high accuracy,specificity,rapid results,and simplicity.Moreover,its performance remains unaffected by the distribution of H.pylori in the stomach,allowing a high flow of patients to be tested.Despite its widespread use,the performance characteristics of UBT have been inconsistently described and remain incompletely defined.There are two UBTs available with Food and Drug Administration approval:The 13C and 14C tests.Both tests are affordable and can provide real-time results.Physicians may prefer the 13C test because it is non-radioactive,compared to 14C which uses a radioactive isotope,especially in young children and pregnant women.Although there was heterogeneity among the studies regarding the diagnostic accuracy of both UBTs,13C-UBT consistently outperforms the 14C-UBT.This makes the 13C-UBT the preferred diagnostic approach.Furthermore,the provided findings of the meta-analysis emphasize the significance of precise considerations when choosing urea dosage,assessment timing,and measurement techniques for both the 13C-UBT and 14C-UBT,to enhance diagnostic precision.

Urea breath test for Helicobacter pylori infection in adult dyspeptic patients: A meta-analysis of diagnostic test accuracy

BACKGROUND Helicobacter pylori(H.pylori)infection has been well-established as a significant risk factor for several gastrointestinal disorders.The urea breath test(UBT)has emerged as a leading non-invasive method for detecting H.pylori.Despite numerous studies confirming its substantial accuracy,the reliability of UBT results is often compromised by inherent limitations.These findings underscore the need for a rigorous statistical synthesis to clarify and reconcile the diagnostic accuracy of the UBT for the diagnosis of H.pylori infection.AIM To determine and compare the diagnostic accuracy of 13C-UBT and 14C-UBT for H.pylori infection in adult patients with dyspepsia.METHODS We conducted an independent search of the PubMed/MEDLINE,EMBASE,and Cochrane Central databases until April 2022.Our search included diagnostic accuracy studies that evaluated at least one of the index tests(^(13)C-UBT or ^(14)C-UBT)against a reference standard.We used the QUADAS-2 tool to assess the methodo-logical quality of the studies.We utilized the bivariate random-effects model to calculate sensitivity,specificity,positive and negative test likelihood ratios(LR+and LR-),as well as the diagnostic odds ratio(DOR),and their 95%confidence intervals.We conducted subgroup analyses based on urea dosing,time after urea administration,and assessment technique.To investigate a possible threshold effect,we conducted Spearman correlation analysis,and we generated summary receiver operating characteristic(SROC)curves to assess heterogeneity.Finally,we visually inspected a funnel plot and used Egger’s test to evaluate publication bias.endorsing both as reliable diagnostic tools in clinical practice.CONCLUSION In summary,our study has demonstrated that ^(13)C-UBT has been found to outperform the ^(14)C-UBT,making it the preferred diagnostic approach.Additionally,our results emphasize the significance of carefully considering urea dosage,assessment timing,and measurement techniques for both tests to enhance diagnostic precision.Nevertheless,it is crucial for researchers and clinicians to evaluate the strengths and limitations of our findings before implementing them in practice.

Accuracy of urea breath test in Helicobacter pylori infection: Meta-analysis

AIM: To quantitatively summarize and appraise the available evidence of urea breath test(UBT) use to diagnose Helicobacter pylori(H. pylori) infection in patients with dyspepsia and provide pooled diagnostic accuracy measures.METHODS: We searched MEDLINE, EMBASE, Cochrane library and other databases for studies addressing the value of UBT in the diagnosis of H. pylori infection. We included cross-sectional studies that evaluated the diagnostic accuracy of UBT in adult patients with dyspeptic symptoms. Risk of bias was assessed using QUADAS(Quality Assessment of Diagnostic Accuracy Studies)-2 tool. Diagnostic accuracy measures were pooled using the random-effects model. Subgroup analysis was conducted by UBT type(13C vs 14C) and by measurement technique(Infrared spectrometry vs Isotope Ratio Mass Spectrometry).RESULTS: Out of 1380 studies identified, only 23 met the eligibility criteria. Fourteen studies(61%) evaluated 13 C UBT and 9 studies(39%) evaluated 14 C UBT. There was significant variation in the type of reference standard tests used across studies.Pooled sensitivity was 0.96(95%CI: 0.95-0.97) andpooled specificity was 0.93(95%CI: 0.91-0.94). Likelihood ratio for a positive test was 12 and for a negative test was 0.05 with an area under thecurve of 0.985. Meta-analyses were associated with a significant statistical heterogeneity that remained unexplained after subgroup analysis. The included studies had a moderate risk of bias.CONCLUSION: UBT has high diagnostic accuracy for detecting H. pylori infection in patients with dyspepsia. The reliability of diagnostic meta-analytic estimates however is limited by significant heterogeneity.

Association between acute pancreatitis and small intestinal bacterial overgrowth assessed by hydrogen breath test

AIM To elucidate the effects of small intestinal bacterial overgrowth(SIBO) on the severity and complications of acute pancreatitis(AP).METHODS In total,208 patients with AP as defined by the revised Atlanta classification were admitted to Xuanwu Hospital of capital Medical University from 2013 to 2016. All patients were admitted within 72 h of AP onset. The hydrogen breath test was performed 7 d after AP onset to detect hydrogen production and evaluate the development of SIBO. The incidence of SIBO was analyzed in patients with AP of three different severity grades. The association between SIBO and complications of AP was also assessed.RESULTS Of the 27 patients with severe AP(SAP),seven(25.92%) developed SIBO. Of the 86 patients with moderately severe AP(MSAP),22(25.58%) developed SIBO. Of the 95 patients with mild AP(MAP),eight(8.42%) developed SIBO. There were significant differences in the rates of SIBO among patients with AP of different severities. Additionally,more severe APwas associated with higher rates of SIBO positivity(P < 0.05). SIBO in patients with AP mainly occurred within 72 h of the onset of AP. The incidence of organ failure was significantly higher in patients with SIBO than in those without(P < 0.05).CONCLUSION SIBO occurs more frequently in patients with MSAP or SAP than in those with MAP,usually ≤ 72 h after AP onset. Additionally,SIBO is associated with organ failure.

Modified Helicobacter test using a new test meal and a 13C-urea breath test in Helicobacter pylori positive and negative dyspepsia patients on proton pump inhibitors

AIM To determine the sensitivity and specificity of the ^(13)C-urea breath test(UBT) in patients taking proton pump inhibitors(PPIs), using a new test meal Refex. METHODS One hundred and fourteen consecutive patients with dyspepsia, 53 Helicobacter pylori(H. pylori) positive, 49 H. pylori negative, were included in the study. The patients were then given esomeprazole 40 mg for 29 consecutive days, and the ^(13)C-UBT with the new test meal was performed the next morning. RESULTS The sensitivity of the ^(13)C-UBT with a cut off 2.5‰ was92.45%(95%CI: 81.79%-97.91%) by per-protocol(PP) analysis and 78.13 %(95%CI: 66.03%-87.49%) by intention-to-treat(ITT) analysis. The specificity of the ^(13)C-UBT test was 96.00 % in the ITT population(95%CI: 86.29%-99.51%) and 97.96% in the PP population(95%CI: 89.15%-99.95%).CONCLUSION The new test meal based ^(13)C-UBT is highly accurate in patients on PPIs and can be used in those unable to stop their PPI treatment.

Four-sample lactose hydrogen breath test for diagnosis of lactose malabsorption in irritable bowel syndrome patients with diarrhea

AIM: To validate 4-sample lactose hydrogen breath testing(4SLHBT) compared to standard 13-sample LHBT in the clinical setting.METHODS: Irritable bowel syndrome patients with diarrhea(IBS-D) and healthy volunteers(HVs) were enrolled and received a 10 g, 20 g, or 40 g doselactose hydrogen breath test(LHBT) in a randomized, double-blinded, controlled trial. The lactase gene promoter region was sequenced. Breath samples and symptoms were acquired at baseline and every 15 min for 3 h(13 measurements). The detection rates of lactose malabsorption(LM) and lactose intolerance(LI) for a 4SLHBT that acquired four measurements at 0, 90, 120, and 180 min from the same data set were compared with the results of standard LHBT.RESULTS: Sixty IBS-D patients and 60 HVs were studied. The genotype in all participants was C/C-13910. LM and LI detection rates increased with lactose dose from 10 g, 20 g to 40 g in both groups(P < 0.001). 4SLHBT showed excellent diagnostic concordance with standard LHBT(97%-100%, Kappa 0.815-0.942) with high sensitivity(90%-100%) and specificity(100%) at all three lactose doses in both groups.CONCLUSION: Reducing the number of measurements from 13 to 4 samples did not significantly impact on the accuracy of LHBT in health and IBS-D. 4SLHBT is a valid test for assessment of LM and LI in clinical practice.

Predisposing factors for positive D-Xylose breath test for evaluation of small intestinal bacterial overgrowth:A retrospective study of 932 patients

AIM: To investigate, in the largest cohort to date, patient characteristics and associated risk factors for developing small intestinal bacterial overgrowth(SIBO) using the D-Xylose breath test(XBT).METHODS: We performed a retrospective crosssectional study to analyze patient characteristics who underwent the XBT for evaluation of SIBO. Diagnostic testing with the XBT was performed based on a clinical suspicion for SIBO in patients with symptoms of bloating, abdominal pain, abdominal distension, weight loss, diarrhea, and/or constipation. Consecutive electronicmedical records of 932 patients who completed the XBT at the University of Florida between 2005 and 2009 were reviewed. A two-way Analysis of Variance(ANOVA) was used to test for several associations including age, gender, and body mass index(BMI) with a +XBT. A two-way ANOVA was also performed to control for the differences and interaction with age and between genders. A similar analysis was repeated for BMI. Associations between medical conditions and prior surgical histories were conducted using the Mantel-Haenszel method for 2 by 2 contingency tables, stratified for gender. Reported odds ratio estimates reflect the odds of the prevalence of a condition within the +XBT group to that of the-XBT group. P values of less than 0.05(two-sided) were considered statistically significant.RESULTS: In the 932 consecutive eligible subjects studied, 513 had a positive XBT. A positive association was found between female gender and a positive XBT(P = 0.0025), and females with a positive test were, on average, greater than 5 years older than those with a negative test(P = 0.024). The mean BMI of positive XBT subjects was normal(24.5) and significantly lower than the subjects with a negative XBT(29.5)(P = 0.0050). A positive XBT was associated with gastroesophageal reflux disease(GERD)(OR = 1.35; 95%CI: 1.02-1.80, P = 0.04), peptic ulcer disease(PUD)(OR = 2.61; 95%CI: 1.48-4.59, P < 0.01), gastroparesis(GP)(OR = 2.04; 95%CI: 1.21-3.41, P < 0.01) and steroid use(OR = 1.35; 95%CI: 1.02-1.80, P = 0.01). Irritable bowel syndrome, independent protonpump inhibitor(PPI) usage, or previous abdominal surgery was not significantly associated with a positive XBT. No single subdivision by gender or PPI use was associated with a significant difference in the odds ratios between any of the subsets. CONCLUSION: Female gender, lower BMI, steroid use, PUD, GERD(independent of PPI use), and GP were more prevalent in patients with SIBO, determined by a positive XBT. Increasing age was associated with SIBO in females, but not in males.

Gender-associated differences in urea breath test for Helicobacter pylori infection referrals and results among dyspeptic patients

AIM: To verify whether there is a gender difference in the 13C-urea breath test results in a large cohort. METHODS: The test results of dyspeptic patients referred for 13C-urea breath testing between January and December, 2007 were evaluated. Testing was carried out at the health insurance organization branches and evaluated at a central laboratory in Israel. RESULTS: Of a total of 28 746 test results, 18 122 (63.04%) were from females and 10 624 (36.95%) from males. Overall, 10 188 (35.4%) results [expressed as delta over baseline (DOB)] were positive (DOB 13C > 5), 18,326 (63.7%) were negative (DOB 13C < 3.5) and 232 (0.8%) were borderline (DOB 13C 3.5-5). There was a significant difference between the total positive rate among females and males (34.8% vs 37.2%, respectively, P = 0.0003). The mean test value was increased by approximately 10 units for females compared to males (P < 0.01) and this difference was consistent for all age groups (i.e., between 10-80 years of age, P < 0.01). CONCLUSION: More females were referred to 13C-urea breath testing. More males had positive results. The mean test values were significantly higher among females of all age groups, possibly representing an increased bacterial load among females and suggesting gender-associated differences in Helicobacter pylori host interactions.

Breath and string test: A diagnostic package for the identification of treatment failure and antibiotic resistance of Helicobacter pylori without the necessity of upper gastrointestinal endoscopy

AIM: Helicobacter pylori (H pylori) resistance after failed eradication has a major impact on the outcome of a further treatment regimen. The aim of this study was to assess the validity of a non-invasive strategy using the 13C-urea breath test (UBT) and the gastric string test in identifying post-treatment resistance of H pylori. METHODS: The UBT was routinely performed 4 to 6 wk after H pylori eradication therapy. Forty-two patients (24 females, 18 males, mean age 48 years) with a positive UBT were included in the study. A gastric string test using a capsule containing a 90 cm-long nylon fiber was performed. Before the capsule was swallowed, the free end of the string was taped to the cheek. After one hour in the stomach, the string was withdrawn. The distal 20 cm of the string was inoculated onto an agar plate and processed under micro-aerophilic conditions. Following the string test, upper gastrointestinal endoscopy was performed to obtain gastric biopsies for conventional culture. RESULTS: H pylori was successfully cultured from the gastric string in 34 patients (81%), but not in 5 patients due to contamination with oropharyngeal flora. H py/oriwas cultured from the gastric biopsies obtained at endoscopy in 39 patients (93%). CONCLUSION: The UBT followed by the gastric string test in the case of treatment failure is a valid diagnostic strategy with the aim of determining the post-therapeutic antibiotic resistance of H pylori with little inconvenience to the patient. Upper Gl-endoscopy can be avoided in several cases by applying consequently this diagnostic package.

Breath test for differential diagnosis between small intestinal bacterial overgrowth and irritable bowel disease:An observation on non-absorbable antibiotics

AIM： To estimate the prevalence of small intestine bacterial overgrowth （SIBO） among patients with an earlier diagnosis of irritable bowel disease （IBS） in our geographical area, and to collect information on the use of locally acting non-absorbable antibiotics in the management of SIBO. METHODS： A non-interventional study was conducted in 73 consecutive patients with a symptom-based diagnosis.. RESULTS： When the patients underwent a ＂breath test＂, 33 （45.2%） showed the presence of a SIBO. Arcer treatment with rifaximin 1200 mg/d for seven days in 32 patients, 19 （59.4%） showed a negative ＂breath test＂ one week later as well as a significant reduction of symptoms, thus confirming the relationship between SIBO and many of the symptoms claimed by patients. In the other 13 patients, ＂breath test＂ remained positive, and a further cycle of treatment with ciprofloxacin 500 mg/d was given for 7 additional days, resulting in a negative ＂breath test＂ in one patient only. CONCLUSION： （1） about half of the patients with a symptomatic diagnosis of IBS have actually SIBO, which is responsible for most of the symptoms attributed to IBS; （2） only a ＂breath test＂ with lactulose （or with glucose in subjects with an intolerance to lactose） can provide a differential diagnosis between IBS and SIBO, with almost identical symptoms; and （3） the use of non-absorbable antibiotics may be useful to reduce the degree of SIBO and related symptoms; it must be accompanied, however, by the correction of the wrong alimentary habits underlying SIBO.

Point-of-care continuous ^(13)C-methacetin breath test improves decision making in acute liver disease: Results of a pilot clinical trial

AIM: To assess the role of the 13C-methacetin breath test (MBT) in patients with acute liver disease. METHODS: Fifteen patients with severe acute liver disease from diverse etiologies were followed-up with 13C-MBT during the acute phase of their illnesses (range 3-116 d after treatment). Patients fasted for 8 h and ingested 75 mg of methacetin prior to the MBT. We compared results from standard clinical assessment, serum liver enzymes, synthetic function, and breath test scores. RESULTS: Thirteen patients recovered and two patients died. In patients that recovered, MBT parameters improved in parallel with improvements in lab results. Evidence of consistent improvement began on day 3 for MBT parameters and between days 7 and 9 for blood tests. Later convergence to normality occurred at an average of 9 d for MBT parameters and from 13 to 28 d for blood tests. In both patients that died, MBT parameters remained low despite fluctuating laboratory values. CONCLUSION: The 13C-MBT provides a rapid, noninvasive assessment of liver function in acute severe liver disease of diverse etiologies. The results of this pilot clinical trial suggest that the MBT may offer greater sensitivity than standard clinical tests for managing patients with severe acute liver disease.

Role of the^(13)C-methacetin breath test in the assessment of acute liver injury in a rat model

AIM: To evaluate the role of the 13C-methacetin breath test(13C-MBT) in the assessment of acute liver injury in a rat model.METHODS: Acute liver injury in rats was induced by a single intraperitoneal injection of D-galactosamine(D-GalN). Forty-eight male Sprague-Dawley rats were randomly assigned to a control group(n = 8) and five model groups(each n = 8), and acute liver injury was assessed at different time points(6, 12, 24, 48 and 72 h) after D-GalN injection. The 13C-MBT, biochemical tests, 15-min retention rate of indocyanine green(ICGR15), and liver biopsy were performed and compared between the control and model groups. Correlations between parameters of the 13C-MBT(Tmax, MVmax, CUM120 and DOBmax), biochemical tests, ICGR15 and liver necrosis score were also analyzed using Spearman'scorrelation analysis.RESULTS: Tmax, MVmax, CUM120 and DOBmax, as well as most of the traditional methods, correlated with the liver necrosis score(r = 0.493, P < 0.05; r =-0.731, P < 0.01; r =-0.618, P < 0.01; r =-0.592, P < 0.01, respectively). MVmax, CUM120 and DOBmax rapidly decreased and were lower than those in the controls as early as 6 h after D-GalN injection(3.84 ± 0.84 vs 5.06 ± 0.78, P < 0.01; 3.35 ± 0.72 vs 4.21 ± 1.44, P < 0.05; 52.3 ± 20.58 vs 75.1 ± 9.57, P < 0.05, respectively) and reached the lowest point 24 h after D-GalN injection. MVmax, CUM120 and DOBmax returned to normal levels 72 h after D-GalN injection and preceded most of the traditional methods, including liver biopsy.CONCLUSION: The 13C-MBT is a sensitive tool for the timely detection of acute liver injury and early prediction of recovery in a rat model. Further clinical studies are warranted to validate its role in patients with acute liver injury.

Effect of DA-9701 on gastric emptying in a mouse model: Assessment by ^(13)C-octanoic acid breath test

AIM:To evaluate the effects of DA-9701 on the gastric emptying of a solid meal using the 13C-octanoic acid breath test in a mouse model. METHODS:Male C57BL/6 mice aged > 8 wk and with body weights of 20-25 g were used in this study. The solid test meal consisted of 200 mg of egg yolk labeled with 1.5 L/g 13C-octanoic acid. The mice were placed in a 130 mL chamber flushed with air at a flow speed of 200 mL/min. Breath samples were collected for 6 h. The half-emptying time and lag phase were calculated using a modified power exponential model. To assess the reproducibility of the 13C-octanoic acid breath test, the breath test was performed two times at intervals of one week in ten mice without drug treatment. To assess the gastrokinetic effects of DA-9701, the breath test was performed three times in another twelve mice, with a randomized crossover sequence of three drug treatments:DA-9701 3 mg/kg, erythromycin 6 mg/kg, or saline. Each breath test was performed at an interval of one week. RESULTS:Repeatedly measured half gastric emptying time of ten mice without drug treatment showed 0.856 of the intraclass correlation coefficient for the half gastric emptying time (P = 0.004). The mean cumulative excretion curve for the 13C-octanoic acid breath test showed accelerated gastric emptying after DA-9701 treatment compared with the saline control (P = 0.028). The median half gastric emptying time after the DA-9701 treatment was significantly shorter than after the saline treatment [122.4 min (109.0-137.9 min) vs 134.5 min (128.4-167.0 min), respectively; P = 0.028] and similar to that after the erythromycin treatment [123.3 min (112.9-138.2 min)]. The lag phase, which was defined as the period taken to empty 15% of a meal, was significantly shorter after the DA-9701 treatment than after the saline treatment [48.1 min (44.6-57.1 min) vs 52.6 min (49.45-57.4 min), respectively; P = 0.049]. CONCLUSION:The novel prokinetic agent DA-9701 accelerated gastric emptying, assessed with repeated measurements in the same mouse using the 13Coctanoic acid breath test. Our findings suggest that DA-9701 has therapeutic potential for the treatment of functional dyspepsia.

An optimized ^(13)C-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.

Validity and cost comparison of ^(14)carbon 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 Py/ori. 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 ^14 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 Hpylori infection in less developed countries.

Diagnostic accuracy of tests for Helicobacter pylori in an Alaska Native population

AIM： TO evaluate the accuracy of two non-invasive tests in a population of Alaska Native persons. High rates of Helicobacter pylori （H. pylon] infection, H. pyIori treatment failure, and gastric cancer in this population necessitate documentation of infection status at multiple time points over a patient＇s life.urease test, 13C urea breath test （UBT）, and immunoglobulin G antibodies to H. pylori in serum. The performances of 13C-UBT and antibody test were compared to a gold standard defined by a positive H. pylori test by culture or, in case of a negative culture result, by positive histology and a positive rapid urease test.RESULTS： The sensitivity and specificity of the 13C- UBT were 93% and 88%, respectively, relative to the gold standard. The antibody test had an equivalent sensitivity of 93% with a reduced specificity of 68%. The false positive results for the antibody test were associated with previous treatment for an H. pylorlinfection [relative risk （RR） = 2.8]. High levels of antibodies to H. py/or/were associated with chronic gastritis and male gender, while high scores in the 13C-UBT test were associated with older age and with theH. pylori bacteria load on histological examination （RR = 4.4）. CONCLUSION： The 13C-UBT outperformed the antibody test for H. pylori and could be used when a noninvasive test is clinically necessary to document treatment outcome or when monitoring for reinfection.

Capsule ^(13)C-urea breath test for the diagnosis of Helicobacter pylori infection

AIM: To compare the accuracy of capsule 13C-urea breath test (UBT) with conventional invasive methods for the diagnosis of Helicobacter pylori infection.METHODS: One hundred patients received CLO test,histological examination, culture and 100- or 50-mg capsule UBT for the diagnosis of Hpyloriinfection. Hpylori infection was defined as those with positive culture or positive results from both histology and CLO test.RESULTS: Both the sensitivity and specificity of the 100-mg capsule UBT (n = 50) were 100%. The sensitivity and specificity of the 50-mg capsule UBT (n = 50) were 96.4and 100%, respectively. Taken together, the accuracy of capsule UBT (n=100) was higher than that of CLO test,histology and culture (100% vs 92%, 91% and 89%,respectively; P= 0.035, 0.018 and 0.005, respectively). Our data showed that the optimal timing of sampling for 100-and 50-mg capsule UBT was 15-30 and 6-15 min, respectively.CONCLUSION: Capsule UBT has a higher accuracy compared with biopsy-based tests. It is an ideal method for the diagnosis of Hpyloriinfection.

Shortness of breath in clinical practice: A case for left atrial function and exercise stress testing for a comprehensive diastolic heart failure workup

The symptom cluster of shortness of breath(SOB) contributes significantly to the outpatient workload of cardiology services. The workup of these patients includes blood chemistry and biomarkers, imaging and functional testing of the heart and lungs. A diagnosis of diastolic heart failure is inferred through the exclusion of systolic abnormalities, a normal pulmonary function test and normal hemoglobin, coupled with diastolic abnormalities on echocardiography. Differentiating confounders such as obesity or deconditioning in a patient with diastolic abnormalities is difficult. While the most recent guidelines provide more avenues for diagnosis, such as incorporating the left atrial size, little emphasis is given to understanding left atrial function, which contributes to at least 25% of diastolic left ventricular filling; additionally, exercise stress testing to elicit symptoms and test the dynamics of diastolic parameters, especially when access to the "gold standard" invasive tests is lacking, presents clinical translational gaps. It is thus important in diastolic heart failure work up to understand left atrial mechanics and the role of exercise testing to build a comprehensive argument for the diagnosis of diastolic heart failure in a patient presenting with SOB.