The effect of dosing with omeprazole on the accuracy of the 13C-urea breath test in Helicobacter pylori-infected subjects

Association between renal function and co-infection with Clonorchis sinensis and Helicobacter pylori: a cross-sectional study

Background

Studies have shown that liver fluke infections may be associated with kidney injury and that Helicobacter pylori (Hp) may be involved in the pathogenesis of kidney diseases. However, no studies have reported the relationship between co-infection with Clonorchis sinensis (Cs) and Hp and renal function. The aim of this study was to examine the relationship between co-infection with Cs and Hp and estimated glomerular filtration rate (eGFR) in a general population, and gender-related differences were also investigated.

Methods

In the cross-sectional study, 4122 subjects from the Health Examination Center of Guangdong Provincial Hospital of Integrated Traditional Chinese and Western Medicine from January 2017 to December 2018 were enrolled. All participants underwent stool examination for the diagnosis of Cs infection and ¹³C-urea breath test (UBT) for the diagnosis of Hp infection. Participants were categorized into four groups: (1) co-infection with Cs and Hp group comprising 207 cases (Hp(+) + Cs(+) group), (2) Cs infection group comprising 1392 cases (Hp(−) + Cs(+)group), (3) Hp infection group comprising 275 cases (Hp(+) + Cs(−) group), and (4) non-infection group comprising 2248 cases (Hp(−) + Cs(−) group). Multiple linear regression analysis was performed to evaluate the relationship between co-infection with Cs and Hp and eGFR.

Results

Hp infection without Cs infection was present in 6.67% (275/4122) of subjects, while Cs infection without Hp infection was present in 33.77% (1392/4122) of subjects. Co-infection with Hp and Cs were present in 5.02% (207/4122) of subjects. Median age of the participants was 43 years (IQR 35–51). Most of the participants were male (2955/4122, 71.69%). Median eGFR was 96.61 ml/min/1.73 m² (IQR 85.05–106.24). Co-infection with Cs and Hp was negatively associated with eGFR after full adjusting (β = − 1.89, 95% CI: − 3.33 to − 0.45, p = 0.01). The relationship remained significant in females (β = − 9.37, 95% CI: − 11.60 to − 7.1, p < 0.001), but not in males.

Conclusion

Our findings suggest that co-infection with Cs and Hp may be associated with reduced renal function in females, but not in males.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-020-05616-0.

Influence of acotiamide on 13C-urea breath test for Helicobacter pylori diagnosis

The Helicobacter pylori infection and functional dyspepsia are often coexisted. The effect of acotiamide, a drug for functional dyspepsia, on the result of Helicobacter pylori diagnosis has yet to be studied. We evaluated the influence of acotiamide on the results of Helicobacter pylori diagnosis in the ¹³C-urea breath test. Twenty patients with Helicobacter pylori-positive functional dyspepsia were treated with 100 mg of acotiamide three times a day for two weeks. Changes in ¹³C-urea breath test were investigated before and after administration, and two weeks after administration as the follow-up period. The ¹³C-urea breath test and the medical questionnaire of modified frequency scale for the symptoms of gastroesophageal reflux disease were conducted at every period. Nineteen patients were included for analysis. No patients showed negative in ¹³C-urea breath test at Weeks 2 and 4. On the symptom scale, dyspepsia and total scores decreased from Week 0 to Week 2 and increased from Week 2 to Week 4, and the improvement rates of the dyspepsia score at Week 2 was 63%. In conclusion, we confirmed that acotiamide is unlikely to influence the result of ¹³C-urea breath test and it may improve the symptoms of functional dyspepsia during Helicobacter pylori eradication treatment.

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.

Epidemiology, clinical impacts and current clinical management of Helicobacter pylori infection

Helicobacter pylori infection is a major cause of morbidity and mortality worldwide. More than 50% of the global population is estimated to be infected. Differences in prevalence exist within and between countries, with higher prevalence seen among people with lower socio-economic status. Most transmission of infection occurs early in life, predominantly from person to person in the family setting. H. pylori is the cause of most peptic ulcer disease, gastric cancer and gastric mucosa-associated lymphoid tissue (MALT) lymphoma and causes symptoms in a subset of patients with functional dyspepsia. Choice of diagnostic test depends on the clinical context; urea breath tests and endoscopy with biopsy are the major diagnostic tools. Evidence-based indications for eradication of H. pylori infection are well documented. The most widely used and recommended eradication therapy in Australia is triple therapy comprising a proton pump inhibitor, amoxycillin and clarithromycin, usually for 1 week. Effective alternative regimens are available for patients with proven allergy to penicillin. Antimicrobial resistance is the major determinant of the outcome of eradication therapy. Trends in antibiotic resistance need to be monitored locally, but individual patient susceptibility testing is not usually necessary as it rarely guides the choice of therapy. The outcome of treatment should be assessed not less than 4 weeks after therapy. This is usually done with a urea breath test if follow-up endoscopy is not required. When first-line therapy fails, several proven second-line therapies may be used. Repeat first-line therapy and ad hoc regimens should be avoided. Overall cumulative eradication rates should approach 99%.

Effect of Vonoprazan, a Potassium-Competitive Acid Blocker, on the 13C-Urea Breath Test in Helicobacter pylori-Positive Patients

BACKGROUND AND AIM

Vonoprazan (VPZ) is a new oral potassium-competitive acid blocker that has recently become available. The aim of this study was to investigate the effects of VPZ on the urease activity of H. pylori as measured by the ¹³C-urea breath test (¹³C-UBT).

PATIENTS AND METHODS

A total of 60 patients (26 men, 34 women; mean age 53.2 ± 13.6 years) who were diagnosed as H. pylori-positive were recruited. The patients were randomly allocated to three treatment groups: lansoprazole (LPZ) 30 mg (n = 20), VPZ 20 mg (n = 20) once daily for 3 weeks, or the control group (n = 20). The ¹³C-UBT was carried out at baseline and after 3 weeks of treatment, and the baseline and after treatment results then compared. Δ¹³C‰ ≥ 2.5‰ was considered H. pylori-positive.

RESULTS

Four patients failed to complete the medication and were omitted from the analysis; data from the LPZ group (n = 18), VPZ group (n = 18), and control group (n = 20) were analyzed. The control group showed no significant change in ¹³C-UBT data between baseline and the completion of 3-week treatment (baseline: 26.6 ± 23.0‰, completion: 21.1 ± 13.1‰). The ¹³C-UBT data at week 3 were significantly decreased in both the VPZ group (baseline: 32.8 ± 22.7‰, completion: 7.6 ± 9.2‰, p = 0.0002) and the LPZ group (baseline: 41.8 ± 33.4‰; completion: 9.6 ± 8.8‰, p = 0.0006) compared to baseline.

CONCLUSIONS

VPZ treatment reduced the value of UBT, warning that UBT for patients with VPZ treatment should be evaluated carefully.

The use of a second biopsy from the gastric body for the detection of Helicobacter pylori using rapid urease test

INTRODUCTION

The use of an additional biopsy from the gastric body may help improve the detection of Helicobacter pylori during endoscopy. This study aimed to determine whether such an additional biopsy is necessary in routine rapid urease test (RUT), and whether acid suppression and antibiotic therapy affect RUT results.

METHODS

Patients recruited had two gastric mucosal biopsies taken - one from the gastric antrum and the other from the gastric body. Each biopsy was placed into separate RUT kits. Information on previous or current use of proton-pump inhibitors, H2 receptor antagonist, bismuth and antibiotics was obtained. Patients on any of those drugs one week prior to endoscopy were considered to have a positive drug history (PDH).

RESULTS

Of the 400 patients recruited, 311 had negative RUTs and 89 had at least one positive RUT. Between the PDH and negative drug history (NDH) groups, there was a significant difference in the distribution of the location of the biopsies that yielded positive RUTs (p = 0.023). The NDH group had a higher proportion of patients who had positive RUTs for both locations, whereas the PDH group had a higher proportion of patients who had positive RUTs for only one location.

CONCLUSION

As RUT results are significantly affected by the use of acid suppression and antibiotic therapies, biopsies for RUT should be taken from both the gastric antrum and body to minimise false negative results.

Influence of proton pump inhibitors on gastritis diagnosis and pathologic gastric changes

AIM: To investigate the influence of proton pump inhibitors (PPIs) exposure on the diagnosis of Helicobacter pylori (H. pylori) gastritis and intestinal metaplasia.

METHODS: Chronic PPI use is associated with masking of H. pylori infection. Patients with H. pylori infection are predisposed to gastric and duodenal ulcers, and long-term infection with this organism has been associated with gastric mucosal atrophy and serious long-term complications, such as gastric lymphoma and adenocarcinoma. Three hundred patients diagnosed with gastritis between January 2008 and April 2010 were included in our study. The computerized medical database of these patients was reviewed retrospectively in order to assess whether the type of gastritis diagnosed (H. pylori vs non-H. pylori gastritis) is influenced by PPI exposure. H. pylori density was graded as low, if corresponding to mild density following the Updated Sydney System, or high, if corresponding to moderate or severe densities in the Updated Sydney System.

RESULTS: Patients were equally distributed between males and females with a median age at the time of diagnosis of 50 years old (range: 20-87). The histological types of gastritis were classified as H. pylori gastritis (n = 156, 52%) and non-H. pylori gastritis (n = 144, 48%). All patients with non-H. pylori gastritis had inactive chronic gastritis. Patients with no previous PPI exposure were more likely to be diagnosed with H. pylori gastritis than those with previous PPI exposure (71% vs 34.2%, P < 0.001). Intestinal metaplasia was more likely to be detected in the latter patients (1.4% vs 6.5%, P = 0.023). Multivariate analysis has also demonstrated that in the presence of previous PPI exposure (OR = 0.217, 95%CI: 0.123-0.385), GERD (OR = 0.317, 95%CI: 0.132-0.763, P = 0.01), alcohol intake (OR = 0.396, 95%CI: 0.195-0.804, P = 0.01), the detection of H. pylori was less likely. Chronic use of PPIs may mask H. pylori infections promoting the diagnosis of non-H. pylori gastritis and leads to a significant drop in H. pylori densities and to an increased risk of intestinal metaplasia.

CONCLUSION: The use of PPIs masks H. pylori infection, promotes the diagnosis of non-H. pylori inactive chronic gastritis diagnosis, and increases the incidence of intestinal metaplasia.

Diagnosis, treatment, and outcome in patients with bleeding peptic ulcers and Helicobacter pylori infections

Upper gastrointestinal (UGI) bleeding is the most frequently encountered complication of peptic ulcer disease. Helicobacter pylori (Hp) infection and nonsteroidal anti-inflammatory drug (NSAID) administration are two independent risk factors for UGI bleeding. Therefore, testing for and diagnosing Hp infection are essential for every patient with UGI hemorrhage. The presence of the infection is usually underestimated in cases of bleeding peptic ulcers. A rapid urease test (RUT), with or without histology, is usually the first test performed during endoscopy. If the initial diagnostic test is negative, a delayed ¹³C-urea breath test (UBT) or serology should be performed. Once an infection is diagnosed, antibiotic treatment is advocated. Sufficient evidence supports the concept that Hp infection eradication can heal the ulcer and reduce the likelihood of rebleeding. With increased awareness of the effects of Hp infection, the etiologies of bleeding peptic ulcers have shifted to NSAID use, old age, and disease comorbidity.

Effect of Helicobacter pylori infection on esophagogastric variceal bleeding in patients with liver cirrhosis and portal hypertension

BACKGROUND AND AIMS

Bleeding from esophageal and gastric varices is a fatal event in patients with liver cirrhosis and portal hypertension. However, the effects of Helicobacter pylori (H. pylori) infection on esophagogastric variceal bleeding are not known. The present study was aimed to elucidate the role of H. pylori infection in esophagogastric variceal bleeding.

METHODS

The subjects were 196 cirrhotic patients who were admitted to the Kurume University Hospital to treat their esophagogastric varices consisted of 95 with acute bleeding and 101 with nonbleeding but high risk of bleeding. For the diagnosis of H. pylori infection, a (13) C-urea breath test was used, and serum pepsinogen (PG) I and II levels and the PG I/II ratio were also measured.

RESULTS

Esophagogastric variceal bleeding was seen in 34.9% (n = 30) of the H. pylori-infected patients (n = 86) and in 59.1% (n = 65) of the noninfected patients (n = 110) (P < 0.0007). There was no significant difference in the infection rate between the bleeding sites of the esophagus and the stomach. The serum PG I and II levels and the PG I/II ratio were 65.6 ng/dL, 14.7 ng/dL, and 4.4, respectively, for the bleeding patients (n = 95), and 43.7 ng/dL, 17.7 ng/dL, and 3.1 for the nonbleeding patients (n = 101). Thus, the nonbleeding patients had significantly higher rate of H. pylori infection and lower acid secretion than bleeding patients (0.001). In addition, multivariate logistic regression analysis showed a significant negative association between H. pylori infection and esophagogastric variceal bleeding.

CONCLUSIONS

These results suggest that H. pylori infection has a protective effect against esophagogastric variceal bleeding through the induction of gastric mucosal atrophy and concomitant hypoacidity.

Influence of proton pump inhibitor treatment on Helicobacter pylori stool antigen test

AIM: To investigate the effects of proton pump inhibitor (PPI) treatment on stool antigen test using the TestMate pylori enzyme immunoassay.

METHODS: This study assessed 28 patients [16 men and 12 women; mean age (63.1 ± 5.9) years; range, 25-84 years] who underwent stool antigen test and urea breath test (UBT) before and after PPI administration.

RESULTS: Using the UBT as the standard, the sensitivity, specificity and agreement of the stool antigen test in all 28 patients were 95.2%, 71.4%, and 89.3%, respectively, before PPI administration, and 88.9%, 90.9%, and 89.3%, respectively, after PPI treatment. Mean UBT values were 23.98% ± 5.33% before and 16.19% ± 4.75% after PPI treatment and, in 15 patients treated for ≥ 4 wk, were significantly lower after than before 4 wk of PPI treatment (12.58% ± 4.49% vs 24.53% ± 8.53%, P = 0.048). The mean optical density (A_450/630) ratios on the stool antigen test were 1.16 ± 0.20 before and 1.17 ± 0.24 after PPI treatment (P = 0.989), and were 1.02 ± 0.26 and 0.69 ± 0.28, respectively, in the group treated for > 4 wk (P = 0.099).

CONCLUSION: The stool antigen test was equally sensitive to the UBT, making it a useful and reliable diagnostic method, even during PPI administration.

Effect of omeprazole, rabeprazole, and rebamipide on the accuracy of urea breath test in patients with Helicobacter pylori infection

Background: The urea breath test (UBT) has been widely used for H. pylori eradication after treatment. The breath test could be adversely affected by various factors including proton pump inhibitors (PPIs) that are also used in the therapy for H. pylori infection. Objective: Determine the effect of omeprazole, rabeprazole and the mucoprotective agent rebamipide, on the UBT. Methods: Fifty-six patients with dyspepsia and positive for H. pylori by rapid urease test were enrolled. They were classified into three groups: Group 1 (n=25) received omeprazole 20 mg once daily, group 2 (n=13) received rabeprazole 20 mg once daily, and group 3 (n=18) received rebamipide 100 mg three times a day. All patients received a 14-day course of their medications. UBT was performed on day 0 as a baseline and on day 14 in all patients. In patient with negative results of UBT on day 14, the UBT was performed in consecutive week until the test became positive. Results: Fifty-six patients (20 men and 36 women) participated in the study. Their mean age was 46.77±14.3 years. False negative rate after 14-day treatment in omeprazole, rabeprazole and rebamipide group were 20.0%, 30.8%, and 0% respectively. There was a significant difference between 13C level in patients with negative and positive UBT results (2.7±0.7 vs.22.9±3.7/mL, p=0.025). The reversal of false negative to true positive tests occurred within two weeks after discontinuation of omeprazole and rabeprazole. Conclusion: Proton pump inhibitors had an effect on the accuracy of H. pylori detection using UBT. Rabeprazole revealed a higher false negative rate in the UBT than omeprazole. The mucoprotective drug, rebamipide, did not influence negative results in the UBT.

Second Asia-Pacific Consensus Guidelines for Helicobacter pylori infection

The Asia-Pacific Consensus Conference was convened to review and synthesize the most current information on Helicobacter pylori management so as to update the previously published regional guidelines. The group recognized that in addition to long-established indications, such as peptic ulcer disease, early mucosa-associated lymphoid tissue (MALT) type lymphoma and family history of gastric cancer, H. pylori eradication was also indicated for H. pylori infected patients with functional dyspepsia, in those receiving long-term maintenance proton pump inhibitor (PPI) for gastroesophageal reflux disease, and in cases of unexplained iron deficiency anemia or idiopathic thrombocytopenic purpura. In addition, a population 'test and treat' strategy for H. pylori infection in communities with high incidence of gastric cancer was considered to be an effective strategy for gastric cancer prevention. It was recommended that H. pylori infection should be tested for and eradicated prior to long-term aspirin or non-steroidal anti-inflammatory drug therapy in patients at high risk for ulcers and ulcer-related complications. In Asia, the currently recommended first-line therapy for H. pylori infection is PPI-based triple therapy with amoxicillin/metronidazole and clarithromycin for 7 days, while bismuth-based quadruple therapy is an effective alternative. There appears to be an increasing rate of resistance to clarithromycin and metronidazole in parts of Asia, leading to reduced efficacy of PPI-based triple therapy. There are insufficient data to recommend sequential therapy as an alternative first-line therapy in Asia. Salvage therapies that can be used include: (i) standard triple therapy that has not been previously used; (ii) bismuth-based quadruple therapy; (iii) levofloxacin-based triple therapy; and (iv) rifabutin-based triple therapy. Both CYP2C19 genetic polymorphisms and cigarette smoking can influence future H. pylori eradication rates.

Helicobacter pylori, anemia, and iron deficiency: relationships explored among Alaska native children

BACKGROUND

Attempts to understand determinants of anemia and iron deficiency have led researchers to examine the role of Helicobacter pylori infection. The current study assessed determinants of anemia and iron deficiency, including H. pylori, in Alaska Native children.

METHODS

In 1999, a population-based survey was conducted among 86 children (67% response rate), mean age of 43.7 months (standard deviation = 16.8 months). Samples of breath, stool, and venous blood were obtained from children for measures of anemia, iron deficiency, H. pylori, fecal blood loss, and current inflammation. Standardized interviews with parents provided information on demographics, illness, and intake of dietary iron, iron-absorption inhibitors, and enhancers.

RESULTS

Of the 86 children studied, 17.4% were anemic and 38.6% were iron deficient. Forty-one percent of the cohort had H. pylori-specific IgG antibodies, 86% tested positive by the urea breath test (UBT), and 80% tested positive by the stool antigen test. Presence of H. pylori antibodies emerged as a significant risk factor for anemia and iron deficiency in adjusted analyses controlling for demographic factors, current inflammation, and antibiotic use. In contrast, children with positive UBT or stool antigen results were significantly less likely to have anemia or iron deficiency than those with negative results.

CONCLUSIONS

Results from different measures of H. pylori may reflect different stages of infection. Relationships between H. pylori and anemia/iron deficiency may depend on the phase of infection measured, with serologic tests reflecting established H. pylori infection associated with anemia/iron deficiency, and UBT and stool antigen results reflecting an earlier stage of infection.

13C-urea breath test during hospitalization for the diagnosis of Helicobacter pylori infection in peptic ulcer bleeding

OBJECTIVE

To evaluate the accuracy of (13)C-urea breath test (UBT) to detect Helicobacter pylori infection in patients hospitalized with peptic ulcer bleeding and treated with proton pump inhibitors (PPIs).

METHODS

Patients hospitalized with peptic ulcer bleeding, and treated with omeprazole, had a first UBT performed the day after resuming oral feeding. Patients with a negative UBT during hospitalization underwent a repeated UBT 15 days after stopping PPIs.

RESULTS

The first UBT during hospitalization was positive in 86% of 131 patients. Time between admission and performance of the test was longer in patients with negative versus positive UBT (5.2 +/- 0.7 versus 4.3 +/- 0.5 days; p < .001). The repeated UBT became positive in 15 of 18 (83%) patients with a negative first UBT. In the multivariate analysis, the only variable associated with a negative first UBT was the time elapsed between admission and performance of the test (odds ratio = 6.6; 95%CI = 2.9-15.1).

CONCLUSION

Most H. pylori-positive patients with ulcer bleeding have a positive UBT (performed just after resuming oral feeding) despite previous treatment with high-dose PPIs. Nevertheless, to preclude false-negative results due to PPI therapy, the UBT should be performed as early as possible. If the infection cannot be demonstrated with this first UBT, H. pylori still needs to be definitively excluded with a second UBT performed after stopping PPIs.

The 13carbon urea breath test for the diagnosis of Helicobacter pylori infection in subjects with atrophic gastritis: evaluation in a primary care setting

BACKGROUND

(13)Carbon urea breath testing is reliable to detect current infection with Helicobacter pylori but has been reported to be of limited value in selected patients with atrophic body gastritis or acid-lowering medication.

AIM

To evaluate the accuracy of (13)carbon urea breath testing for H. pylori detection in 20 asymptomatic patients with histologically confirmed atrophic body gastritis in a primary care setting.

METHODS

(13)Carbon urea breath testing and serology were compared with H. pylori culture of a corpus biopsy as reference test.

RESULTS

All tests were in agreement in 12 patients, being all positive in six and all negative in six. One patient was positive for serology and culture but negative for (13)carbon urea breath testing, five patients had only positive serology and two patients had only positive (13)carbon urea breath testing. (13)Carbon urea breath testing showed an accuracy with culture of 85% and anti-H. pylori serology with culture of 75%. (13)Carbon urea breath testing carried out in patients with positive serology showed an accuracy of 92%. Receiver operating characteristic curve analysis of (13)carbon urea breath testing shows optimal discrimination at the prescribed cut-off value.

CONCLUSIONS

(13)Carbon urea breath testing can be used as diagnostic H. pylori test in asymptomatic patients with atrophic body gastritis, preferably in addition to serology, to select subjects for anti-H. pylori therapy.

Accuracy of Helicobacter pylori diagnostic tests in patients with bleeding peptic ulcer: a systematic review and meta-analysis

OBJECTIVE

To perform a systematic review and a meta-analysis of diagnostic accuracy of the different tests aimed to detect Helicobacter pylori infection in patients with upper gastrointestinal bleeding (UGIB).

SELECTION OF STUDIES

assessing the accuracy of H. pylori diagnostic methods in patients with UGIB.

SEARCH STRATEGY

electronic bibliographical searches.

DATA EXTRACTION

independently done by two reviewers.

DATA SYNTHESIS

meta-analyses of the different tests were performed combining the sensitivities, specificities, and likelihood ratios (LRs) of the individual studies.

RESULTS

Studies showed a high degree of heterogeneity. Pooled sensitivity, specificity, LR+ and LR- (95% confidence interval (CI)) for the different methods were: Rapid urease test (16 studies/1,417 patients): 0.67 (0.64-0.70), 0.93 (0.90-0.96), 9.6 (5.1-18.1), and 0.31 (0.22-0.44). Histology (10 studies/827 patients): 0.70 (0.66-0.74), 0.90 (0.85-0.94), 6.7 (2.5-18.4), and 0.23 (0.12-0.46). Culture (3 studies/314 patients): 0.45 (0.39-0.51), 0.98 (0.92-1.00), 19.6 (4-96), and 0.31 (0.05-1.9). Urea breath test (8 studies/520 patients): 0.93 (0.90-0.95), 0.92 (0.87-0.96), 9.5 (3.9-23.3), and 0.11 (0.07-0.16). Stool antigen test (6 studies/377 patients): 0.87 (0.82-0.91), 0.70 (0.62-0.78), 2.3 (1.4-4), and 0.2 (0.13-0.3). Serology (9 studies/803 patients): 0.88 (0.85-0.90), 0.69 (0.62-0.75), 2.5 (1.6-4.1), and 0.25 (0.19-0.33).

CONCLUSION

Biopsy-based methods, such as rapid urease test, histology, and culture, have a low sensitivity, but a high specificity, in patients with UGIB. The accuracy of 13C-urea breath test remains very high in these patients. Stool antigen test is less accurate in UGIB. Although serology seems not to be influenced by UGIB, it cannot be recommended as the first diagnostic test for H. pylori infection in this setting.

13C-urea breath test in the management of Helicobacterpylori infection

The urea breath test is a noninvasive and very accurate test for the diagnosis of Helicobacter pylori infection. However, false negative urea breath test results have been reported to occur in a considerable percentage of the individuals taking proton pump inhibitors; the interval needed to be completely confident that false negative tests had been excluded has varied among the different studies between 6 and 14 days. The impact of H(2)-receptor antagonists on the accuracy of urea breath test remains controversial, although, in contrast with proton pump inhibitors, the data suggest that H(2)-receptor antagonists, for the most part, have little effect on the result of the urea breath test. The urea breath test does not represent a suitable tool for estimating the density of H. pylori colonization. The only quantitative information to be obtained from the urea breath test is that the higher the delta value, the lower the probability of a false-positive urea breath test result. Although some authors have demonstrated a correlation between urea breath test values and histological lesions of the gastric mucosa, the practical utility of this relationship remains unclear. It has been suggested that the pretreatment urea breath test has the potential to identify patients who require modification of the standard therapeutic regimen (for example, prolonging the duration of treatment or increasing the pharmacological dose when bacterial density is high), but other studies could not confirm this relationship. Some studies have shown that the urea breath test is less accurate in patients who have undergone partial gastrectomy. Finally, in contrast with biopsy-based methods, which are responsible for a high number of false-negative results when used to diagnose H. pylori infection in patients with upper gastrointestinal bleeding, urea breath test seems not to be negatively influenced by the presence of this complication.

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.

Masking of 13C urea breath test by proton pump inhibitors is dependent on type of medication: comparison between omeprazole, pantoprazole, lansoprazole and esomeprazole

BACKGROUND

The need to withhold acid suppression therapy while awaiting urea breath test results is a common clinical problem in symptomatic patients. It is unclear at present if the dose or type of proton pump inhibitor or the type of test meal govern the apparent masking effect of proton pump inhibitors on the urea breath test.

AIM

To prospectively evaluate Helicobacter pylori detection rates during treatment with four different proton pump inhibitors, utilizing a high-dose citric acid-based 13C urea breath test.

METHODS

Patients positive for Helicobacter pylori by urea breath test were randomized to receive either omeprazole 20 mg/day, pantoprazole 40 mg/day, lansoprazole 30 mg/day or esomeprazole 40 mg/day for 14 days. A repeat breath test was performed on day 14 of treatment.

RESULTS

One hundred and seventy-nine patients, mean age 45.8 +/- 16.8, completed the study. Treatment with omeprazole or pantoprazole prior to urea breath test (UBT) was associated with low false negative results, while lansoprazole and esomeprazole caused clinically unacceptable high false negative rates (pantoprazole 2.2% vs. lansoprazole 16.6%, P = 0.02, vs. esomeprazole 13.6%, P = 0.05; omeprazole 4.1% vs. lansoprazole 16.6%, P = 0.05).

CONCLUSIONS

Proton pump inhibitor-induced false negative results on high-dose citric acid based urea breath test vary with the type of proton pump inhibitor used. Selection of the appropriate test meal and proton pump inhibitor may allow symptomatic individuals to continue their proton pump inhibitors prior to performing a urea breath test.

Effect of proton pump inhibitors and antacid therapy on 13C urea breath tests and stool test for Helicobacter pylori infection

OBJECTIVE

There is uncertainty about the best method of testing patients for Helicobacter pylori (H. pylori) infection while they are taking proton pump inhibitors. The aim of this study was to determine: (i) if the decreased sensitivity of the urea breath test during proton pump inhibitor is corrected by different techniques for breath testing and (ii) if the sensitivity of stool test is decreased with the administration of proton pump inhibitors.

METHODS

Prospective randomized single-blind study was performed in a tertiary care university hospital. Out of 72 H. pylori infected patients endoscoped for upper abdominal symptoms 48 were randomized to proton pump inhibitors (omeprazole 20 mg each day or esomeprazole 40 mg each day) and 24 to antacid (aluminum hydroxide 800 mg each day) for 14 days. Several breath tests (standard 75 mg (13)C-UBT with citric acid, with orange juice, a tablet breath test with 100 and 50 mg of (13)C), and a stool test were carried out. Baseline samples were collected before and after treatment.

RESULTS

The baseline sensitivity for all breath tests was 100% in both groups; for stool test it was 97.8% (95% CI: 88.7-96.6) and 90% (95% CI: 69.9-97.2) in the proton pump inhibitor and antacid group, respectively. After treatment, the sensitivity of tests was significantly low (UBTs range: 77.1%-85.4%; stool test: 83%; 95% CI: 63.9-91.1), while it was unchanged in the antacid group.

CONCLUSIONS

False negative breath and stool tests are equally common in patients taking proton pump inhibitors. Antacids do not impair the sensitivity of the breath tests or the stool test.

Studies regarding the mechanism of false negative urea breath tests with proton pump inhibitors

OBJECTIVE

The mechanism of false negative urea breath tests (UBTs) results among proton pump inhibitor (PPI) users is unknown. We studied the time course of PPI-associated negative UBT, the relation to Helicobacter pylori density, and whether gastric acidification would prevent false negative UBT results.

METHOD

In the UBT experiment, H. pylori-infected volunteers received omeprazole 20 mg b.i.d. for 13.5 days. UBTs with citric acid were done before, after 6.5 days of PPI, and 1, 2, 4, 7, and 14 days after therapy. In the culture and histology experiment, after a wash-out of >5 months, nine of the original subjects were rechallenged with omeprazole for 6.5 days. Antral and corpus biopsies for histology and culture were done before and 1 day after PPI administration.

RESULTS

Thirty subjects (mean age 42 yr) were enrolled. UBTs were significantly reduced on day 6.5 (p = 0.031); 10 subjects (33%) developed transient negative UBTs. The UBT recovered in all but one subject by the fourth day post-PPI and in all subjects by day 14. In the culture and histology experiment, upon PPI rechallenge, three of nine subjects (33%) had negative UBTs. H. pylori density, whether measured by culture or histology, decreased with PPI therapy; antral biopsies became histologically negative in five subjects and corpus biopsies in three subjects.

CONCLUSION

PPI-induced negative UBT results were related to the anti-H. pylori effect of the PPI. Acidification of the stomach did not prevent false negative UBT results. Three days is likely the minimum delay from stopping PPI until one should perform a test for active infection. A delay of 14 days is preferred.

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.

Effect of proton pump inhibitors on the continuous real time (13)C-urea breath test

OBJECTIVE

The aim of this study was to evaluate the accuracy of a new, continuous real time (13)C-urea breath test, BreathID, for the diagnosis of Helicobacter pylori in patients taking proton pump inhibitors (PPIs).

METHODS

Fifty-two consecutive patients, positive for H. pylori by BreathID, were prospectively evaluated. Patients were randomized to receive either omeprazole 20 mg/day or pantoprazole 40 mg/day for 14 days. A repeat breath test was performed on day 14 while patients received their last PPI pill. Patients were given a test drink containing 75 mg (13)C-urea and 4.0 g citric acid. Real time, continuously sampled expired (13)CO(2), obtained within 6-20 min, was compared with measurement of expired (13)CO(2) by isotope ratio mass spectrometry (IRMS).

RESULTS

A full set of test data was available for 43 patients. After 14 days of treatment with PPIs, false negative detection of H. pylori occurred in only 1/43 (2.3%) patients examined by continuous real time (13)C-urea breath test compared with 2/43 (4.6%) patients examined by IRMS. With the exception of one case, complete agreement was observed between BreathID and the IRMS breath tests at both baseline and after PPI treatment. PPI treatment was associated with three different types of responses on UBT: 1) one third of the patients developed a significant decrease in the (13)CO(2)/(12)CO(2) excretion, 2) roughly one third developed a significant increase in the post-PPI breath test results, and 3) results did not change significantly in the remaining patients. Linear regression analysis of 43 H. pylori-positive subjects indicated a significant positive association between baseline and post-PPI Delta (13)CO(2)/(12)CO(2) excretion.

CONCLUSIONS

The use of a single test drink containing 4.0 g citric acid in BreathID, resulted in a low number of false negative results associated with sustained PPI treatment. Although there were some differences between BreathID versus IRMS, the type of PPI and the sampling method used do not appear to play a critical role in the detection of H. pylori by BreathID. According to these results, BreathID is a reliable tool for testing H. pylori in patients taking PPIs.

A new semiquantitative method of quantifying Helicobacter pylori in antigen stools

Stool antigen test for Helicobacter pylori, a noninvasive assay, is emerging as a strong competitor to urea breath test (UBT). Nevertheless, although the UBT delta value is a semiquantitative indicator of H. pylori intragastric load, until now the H. pylori stool antigen test has been used only as a qualitative investigation. We report here the results of a study performed with the aim of obtaining a semiquantitative measurement of bacterial amount in stools. We studied 15 patients with dyspepsia using H. pylori positivity at histology, the rapid urease test, UBT, and the H. pylori stool antigen test. The result of this last test was expressed by a numerical value we obtained by applying the principle of "standard points" to the absorbance units at spectrophotometric reading. This measurement was previously validated by testing probe sampling of H. pylori stool antigen with known pure and stool-mixed bacterial amounts. A numerical result for H. pylori stool antigen was correlated to UBT delta for each patient using Pearson's r test. Finally, a Student t test was performed to investigate possible differences in UBT and H. pylori stool antigen test values between anti-CagA-positive and -negative patients. We obtained a curve of saturation with both known amount of pure and stool-mixed bacteria. Pearson's r test showed a significant correlation between UBT delta value and H. pylori stool antigen measurement (r = 0.77; p < 0.001). Urea breath test delta and H. pylori stool antigen test values were significantly higher in anti-CagA-positive patients. Our data suggest that a numerical estimation of H. pylori stool antigen may be feasible. This evaluation, similarly to UBT delta, may represent a semiquantitative determination of bacterial intragastric load.

Using breath tests wisely in a gastroenterology practice: an evidence-based review of indications and pitfalls in interpretation

Breath tests are a simple and safe alternative to more invasive investigation strategies for many gastroenterological conditions. Both the hydrogen breath tests and the new 13C stable radioisotope breath tests are nonradioactive and safe in children and pregnancy. The range of diseases that can be identified include Helicobacter pylori infection, lactose and fructose intolerance, bacterial overgrowth, bile salt wastage, pancreatic insufficiency, liver dysfunction, and abnormal small bowel transit. In this review, the physiology supporting these tests and the principles of normal gas dynamics in the gut are briefly reviewed and then related to the test preparation and interpretation in two parts: 1) detection of H. pylori and 2) small bowel, pancreatic, and hepatobiliary disorders. A MEDLINE search reviewing all English language abstracts from 1966 to March, 2001 was performed, with an additional review of abstracts from major national meetings from 1997 to 2001. Using the information from this review, the performance characteristics of the various tests were detailed, and an attempt is made to provide some literature-based guidance regarding their indications and limitations. The interpretation of "flat" breath tests and the selective use of methane collection and colonic alkalinization are discussed. Breath tests are valuable tools that are, in general, underutilized in evaluating dyspepsia and functional bloating and diarrhea, as well as suspected malabsorption, including lactose intolerance.

Guidelines in the management of Helicobacter pylori infection in Japan

BACKGROUND

In preparation of the approval of Helicobacter pylori therapy by the Japanese national health system, the board of directors of the Japanese Society for Helicobacter Research decided to prepare guidelines on the diagnosis and treatment of H. pylori infection for physicians in routine medical practice.

METHODS

A guidelines preparation committee was formed and six meetings were held. Then, in December 1999, a consensus meeting was held in Kobe to obtain the opinions of general practitioners as well as experts from Europe, North America, and Asia.

RESULTS

Helicobacter pylori eradication therapy is recommended in gastric or duodenal ulcer patients. Helicobacter pylori eradication therapy is recommended or gastric mucosa associated lymphoid tissue (MALT) lymphoma but it should be done at specialist institutions. The significance of H. pylori eradication therapy is still under evaluation in patients with hyperplastic polyps, chronic atrophic gastritis, non-ulcer dyspepsia and in patients after endoscopic mucosal resection of gastric cancer and after gastrectomy for gastric cancer. When diagnosing H. pylori infection, at least one of the tests requiring endoscopic biopsy (e.g. rapid urease test, histology, or culture) and tests not requiring biopsy (e.g. measurement of H. pylori antibody or urea breath test) should be used. Multiple tests are recommended to increase the accuracy. The drugs of first choice currently covered by the national health insurance system in Japan are: lansoprazole (30 mg) 1 capsule twice daily, amoxicillin (250 mg) 3 capsules twice daily, and clarithromycin (200 mg) 1-2 tablets twice daily. These three drugs should be administered after breakfast and dinner for 1 week.

CONCLUSION

These guidelines are intended for utilization in routine medical practice after the Japanese national health system begins to cover the management of H. pylori infection.

Negative effect of ranitidine on the results of urea breath test for the diagnosis of Helicobacter pylori

OBJECTIVES

In analogy with proton pump inhibitors, H2-antagonists may also be responsible for false-negative results on urea breath test for the detection of Helicobacter pylori. In this study we assessed the frequency and duration of false-negative urea breath tests in patients given different doses of ranitidine.

METHODS

A total of 120 consecutive dyspeptic patients infected with H. pylori on the basis of concomitant positive results of CLO-test, histology and urea breath test were recruited for this prospective, open, parallel-group study performed in an urban university gastroenterological clinic. They were randomized to receive an acute treatment with either ranitidine 300 mg once a day in the evening, ranitidine 300 mg once a day in the morning, ranitidine 150 mg b.i.d., or ranitidine 300 mg b.i.d. for 14 days. The urea breath test was performed on day 14 while patients were still taking ranitidine, and on day 21, 1 wk after completion of therapy. The test was repeated on day 28 in those patients who were still negative on day 21. Duplicate breath samples were collected after ingestion of 75 mg 13C-urea plus citric acid. A delta value >5/1000 was considered positive.

RESULTS

Of 118 patients infected with H. pylori, 15 (13%) had a negative urea breath test on day 14. The false-negative results were equally distributed among the four groups of ranitidine dosage. Nine of these patients reverted to positive at 7 days and the remaining six at 14 days after completion of therapy.

CONCLUSIONS

Our study shows that ranitidine negatively affects the results of urea breath testing, independent of the given dosage. Patients undergoing this examination for H. pylori diagnosis should discontinue use of H2-antagonists 2 wk before testing.

Accuracy of the stool antigen test in the diagnosis of Helicobacter pylori infection before treatment and in patients on omeprazole therapy

AIM

To evaluate the Helicobacter pylori stool antigen (HpSA) test in the assessment of H. pylori infection and the effect of omeprazole treatment on its accuracy.

METHODS

Study 1: 140 dyspeptic patients were enrolled in the study and defined as H. pylori positive if histology and rapid urease test, or culture alone were positive. HpSA was performed on all patients and 13C-urea breath test (UBT) on 87. Study 2: 75 patients testing positive using both UBT and HpSA, were given omeprazole 20 mg for 2 weeks (Group A) or omeprazole 40 mg for 2 weeks (Group B), or OAC for 1 week (group C). A Helicobacter pylori stool antigen test was performed on all patients on days 3, 5, 7 and 14 during treatment, and also on days 7 and 14 post-treatment in groups A and B. UBT was performed in groups A and B on days 7 and 14 during treatment, and days 7 and 14 post-treatment.

RESULTS

80/140 patients were H. pylori positive. The sensitivity and specificity of HpSA were 93.8 and 90%, similar to UBT (93.9 and 92.1%). Omeprazole significantly reduced both HpSA and UBT values, resulting in a decreased accuracy. Of 25 patients receiving 20 mg omeprazole, HpSA gave 5 and 6 false negatives after 7 and 14 days treatment respectively, while UBT gave 4 and 7 false negatives after 7 and 14 days treatment. Of 25 patients receiving 40 mg omeprazole, HpSA gave 7 and 9 false negatives after 7 and 14 days of treatment, while UBT gave 8 and 9 false negatives after 7 and 14 days of treatment. Two weeks after stopping omeprazole treatment, the HpSA and UBT were positive in all cases.

CONCLUSIONS

The Helicobacter pylori stool antigen test is valuable in the assessment of H. pylori infection. Short-term omeprazole treatment decreases the accuracy of both HpSA and UBT in a similar manner.

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.

[Efficacy of four widely used techniques of the diagnosis of Helicobacter pylori infection in gastric ulcer disease]

OBJECTIVE

To study the accuracy of four currently used tests for the diagnostic of Helicobacter pylori infection among gastric ulcer patients with a gold standard as reference which combines several diagnostic methods.

MATERIAL AND METHODS

Seventy-three consecutive gastric ulcer patients were prospectively studied. From all patients, three biopsies each were obtained from both antrum and body (two for haematoxylin-eosin staining and one for rapid urease test--Jatrox H.p. Test--. Also, IgG ELISA serology (Helico G) and 13C-urea breath test were performed. According to the gold standard, a patient was considered to be infected with H. pylori when at least two tests were positive; a patient was considered not to be infected with H. pylori when at least three tests were negative.

RESULTS

Among gastric ulcer patients, the prevalence of H. pylori infection was 87.6% (95% CI: 78%-93%) with the gold standard as reference. The sensitivity and specificity values were as follows: histology (antrum), 96.8% (89%-99%) and 100% (66%-100%), respectively; histology (body), 98.4% (91%-100%) and 100% (66%-100%); urease test (antrum), 71.8% (60%-81%) and 100% (66%-100%); urease test (body), 96.8% (89%-99%) and 100% (66%-100%); breath test, 100% (94%-100%) and 100% (66%-100%), and serology, 95.3% (87%-98%) and 100% (66%-100%). The sensitivity of the urease test was higher with a body biopsy specimen (McNemar: 15; p < 0.001).

CONCLUSIONS

All diagnostic tests (histology, rapid urease test, 13C-urea breath test and serology) are highly accurate for the diagnosis of H. pylori infection among gastric ulcer patients with the exception of the rapid urease test performed with antrum biopsy specimens, where this test displays a lower sensitivity for bacterial detection.

Effect of gastric acid suppression on 13C-urea breath test: comparison of ranitidine with omeprazole

BACKGROUND

The assessment of the effect of H2 antagonists on the results of the urea breath test has produced controversial results.

AIM

To assess whether standard doses of both omeprazole and H2 blockers can adversely influence the accuracy of the urea breath test.

METHODS

Sixty dyspeptic patients with ascertained Helicobacter pylori infection were recruited for this prospective, open study. They were randomized to receive either omeprazole 20 mg at 08:00 hours (n = 30) or ranitidine 300 mg at 22:00 hours (n = 30) for 14 days. The urea breath test was performed at baseline, on day 14, while patients were still taking the antisecretory drugs, and on day 21, 1 week after their cessation. Duplicate breath samples were collected after ingestion of 75 mg 13C-urea + citric acid. A delta value > 5 per thousand was considered positive.

RESULTS

On day 14 the median delta values had declined, but not significantly (P = 0. 07) compared to baseline (13.79 vs. 22.39) with omeprazole, while they had increased (P = 0.27) with ranitidine (27.21 vs. 19.46). On the same day there were five out of 30 (17%) and five out of 28 (18%) false-negative results in the omeprazole and ranitidine groups, respectively. All these cases became positive again on day 21. However, in eight cases treated with omeprazole and 13 treated with ranitidine, there was an increase of 14-day delta values compared to baseline.

CONCLUSIONS

Our study shows that both omeprazole and ranitidine at standard doses are able to negatively affect the results of the urea breath test. Their adverse effect resolves within 7 days of drug cessation and therefore the withdrawal of these drugs 7 days before testing seems to be sufficient to avoid false-negative results. The surprising finding that both antisecretory drugs reduce delta values in one group and increase them in another group of patients deserves further study.