The cost-effectiveness of diagnostic testing strategies for Helicobacter pylori

A Culture-Based Strategy Is More Cost Effective Than an Empiric Therapy Strategy in Managing Pediatric Helicobacter pylori Infection

BACKGROUND

Helicobacter pylori infection is a major cause of peptic ulcers and gastric cancer. This study aimed to compare the eradication rate and essential costs of culture-based and empiric therapy strategies in treating pediatric H. pylori infection.

METHODS

We retrospectively enrolled patients aged <18 years with a diagnosis of H. pylori infection who received esophagogastroduodenoscopy at two medical centers in southern Taiwan from 1998 to 2018. Patients with positive cultures and minimum inhibitory concentration test results were allocated to a culture-based strategy, and those with negative cultures or without culture as an empiric therapy strategy. We collected demographic data and eradication rates, and calculated the total essential costs of treating a hypothetical cohort of 1,000 pediatric patients based on the two strategies.

RESULTS

Ninety-six patients were enrolled, of whom 55 received a culture-based strategy and 41 received an empiric therapy strategy. The eradication rates with the first treatment were 89.1 and 75.6% in the culture-based and empiric therapy strategy, respectively. There were no significant differences in age, sex, and endoscopic diagnosis between the two strategies. For every 10% increase in those receiving a culture-based strategy, the total cost would have been reduced by US$466 in a hypothetical cohort of 1,000 patients. For every 10% increase in successful eradication rate, the total cost was reduced by US$24,058 with a culture-based strategy and by US$20,241 with an empiric therapy strategy.

CONCLUSIONS

A culture-based strategy was more cost effective than an empiric therapy strategy in treating pediatric H. pylori-infected patients.

Efficiency of Diagnostic Testing for Helicobacter pylori Infections-A Systematic Review

Background: The most recommended treatment for a Helicobacter pylori infection is high doses of combined antibiotics. The objective of this article is to perform a systematic review of the economic evaluation studies applied to assess the efficiency of diagnostic testing for H. pylori infections, so that their main characteristics can be identified and to learn from the literature how the antimicrobial resistance (AMR) issue is incorporated into these economic evaluations. Methods: We conducted a systematic review to compare the costs and clinical effectiveness of diagnostic strategies for H. pylori infections. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and extracted the items from the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist. Results: We found thirteen articles that were of good quality according to CHEERS: six studies focused on diagnostics of Helicobacter pylori infections associated with dyspepsia and four on duodenal ulcers. Testing was found to be the most cost-effective strategy in eight articles. Four studies considered AMR. Conclusions: Testing was more cost-effective than empirical treatment, except in cases of high prevalence (as with developing countries) or when patients could be stratified according to their comorbidities. The introduction of AMR into the model may change the efficiency of the testing strategy.

The effect of vitamin D deficiency on eradication rates of Helicobacter pylori infection

Background/Aim

Many studies have investigated risk factors other than antibiotic resistance linked to Helicobacter pylori (H. pylori) eradication failure. The aim of this study was to study the effect of serum levels of 25‐hydroxy‐vitamin D (25[OH]D) on eradication rates of H. pylori infection.

Methods

This study included 150 patients diagnosed with H. pylori gastritis using magnifying narrow‐band imaging endoscopy supported by stool antigen test. Serum 25‐OH vitamin D levels were measured via the Enzyme‐Linked Immune Sorbent assay (ELISA) method before starting eradication therapy of H. pylori infection. All patients were treated with clarithromycin‐based triple therapy for 14 days. H. pylori eradication was determined via a stool antigen test performed 4 weeks after the end of therapy. According to the serum level of 25‐OH vitamin D levels, the patients were divided into two groups: group I (sufficient) had a vitamin D level of ≥20 ng/mL, while group II (deficient) had a vitamin D level of <20 ng/mL.

Results

Our results revealed that eradication was successful in 105 (70%) patients and failed in 45 (30%) patients. The mean 25[OH]D level was significantly lower in the eradication failure group compared to the successful treatment group (14.7 ± 4.5 vs 27.41 ± 7.1; P < 0.001). Furthermore, there were significantly more patients with deficient 25[OH]D levels in the failed treatment group, 30 (66.6%), compared to the successful group, 10 (9.5%) (P < 0.001).

Conclusions

Our results demonstrated that 25‐OH vitamin D deficiency may be considered a risk factor related to eradication failure of H. pylori infection. In addition, a further randomized trial to evaluate the effect of vitamin D supplementation in H. pylori eradication is mandatory.

Diagnostic Methods of Helicobacter pylori Infection for Epidemiological Studies: Critical Importance of Indirect Test Validation

Among the methods developed to detect H. pylori infection, determining the gold standard remains debatable, especially for epidemiological studies. Due to the decreasing sensitivity of direct diagnostic tests (histopathology and/or immunohistochemistry [IHC], rapid urease test [RUT], and culture), several indirect tests, including antibody-based tests (serology and urine test), urea breath test (UBT), and stool antigen test (SAT) have been developed to diagnose H. pylori infection. Among the indirect tests, UBT and SAT became the best methods to determine active infection. While antibody-based tests, especially serology, are widely available and relatively sensitive, their specificity is low. Guidelines indicated that no single test can be considered as the gold standard for the diagnosis of H. pylori infection and that one should consider the method's advantages and disadvantages. Based on four epidemiological studies, culture and RUT present a sensitivity of 74.2–90.8% and 83.3–86.9% and a specificity of 97.7–98.8% and 95.1–97.2%, respectively, when using IHC as a gold standard. The sensitivity of serology is quite high, but that of the urine test was lower compared with that of the other methods. Thus, indirect test validation is important although some commercial kits propose universal cut-off values.

Impact of patient adherence on the cost-effectiveness of noninvasive tests for the initial diagnosis of Helicobacter pylori infection in the United States

OBJECTIVE

Previous US-based economic models of noninvasive tests for diagnosis of Helicobacter pylori infection did not consider patient adherence or downstream costs of continuing infection. This analysis evaluated the long-term cost-effectiveness of the urea breath test (UBT), fecal antigen test (FAT), and serology for diagnosis of H. pylori infection after incorporating information regarding test adherence.

MATERIALS AND METHODS

A decision-analytic model incorporating adherence information evaluated the cost-effectiveness of the UBT, FAT, and serology for diagnosis of H. pylori infection. Positive test results led to first-line triple therapy; no further action was taken for nonadherence or negative results. Excess lifetime costs and reduced quality-adjusted life-years (QALYs) were estimated for patients with continuing H. pylori infection.

RESULTS

In the base-case scenario with estimated adherence rates of 86%, 48%, and 86% for the UBT, monoclonal FAT, and serology, respectively, corresponding expected total costs were US$424.99, $466.41, and $404.98/patient. Test costs were higher for the UBT, but were fully or partially offset by higher excess lifetime costs for the monoclonal FAT and serology. The QALYs gained/patient with the UBT vs monoclonal FAT and serology were 0.86 and 0.27, respectively. The UBT was dominant vs the monoclonal FAT, leading to lower costs and higher QALYs; the UBT was cost-effective vs serology (incremental cost/QALY gained $74).

CONCLUSION

Based on a comprehensive modeled analysis that included consideration of patient test adherence and long-term consequences resulting from continuing H. pylori infection, the UBT provided the greatest economic value among noninvasive tests for diagnosis of H. pylori infection, because of high patient adherence and excellent test performance.

Cost-effectiveness analysis of universal noninvasive testing for post-treatment confirmation of Helicobacter pylori eradication and the impact of patient adherence

BACKGROUND

The treatment failure rate for Helicobacter pylori eradication therapy is ~20% due to poor patient compliance and increased antibiotic resistance. This analysis assessed the cost-effectiveness of universal post-treatment testing to confirm eradication of H. pylori infection in adults.

METHODS

Decision-analytic models evaluated the cost-effectiveness of universal post-treatment testing (urea breath test [UBT] or monoclonal fecal antigen test [mFAT]) vs no testing (Model 1), and UBT vs mFAT after adjusting for patient adherence to testing (Model 2) in adults who previously received first-line antimicrobial therapy. Patients testing positive received second-line quadruple therapy; no further action was taken for those testing negative or with no testing (Model 1) or for those nonadherent to testing (Model 2). In addition to testing costs, excess lifetime costs and reduced quality-adjusted life-years (QALYs) due to continuing H. pylori infection were considered in the model.

RESULTS

Expected total costs per patient were higher for post-treatment testing (UBT: US$325.76; mFAT: US$242.12) vs no testing (US$182.41) in Model 1 and for UBT (US$336.75) vs mFAT (US$326.24) in Model 2. Expected QALYs gained per patient were 0.71 and 0.72 for UBT and mFAT, respectively, vs no testing (Model 1), and the same was 0.37 for UBT vs mFAT (Model 2). The estimated incremental costs per QALY gained for post-treatment testing vs no testing were US$82.90-US$202.45 and, after adjusting for adherence, US$28.13 for UBT vs mFAT.

CONCLUSION

Universal post-treatment testing was found to be cost-effective for confirming eradication of H. pylori infection following first-line therapy. Better adherence to UBT relative to mFAT was the key to its cost-effectiveness.

Routine Screening Endoscopy before Bariatric Surgery: Is It Necessary?

Background: Routine esophagogastroduodenoscopy (EGD) prior to bariatric surgery has not been consistently shown to change the management of the patient. A study was performed to estimate the proportion of patients undergoing bariatric surgery evaluation who had abnormal findings on preoperative EGD that resulted in alteration of management and, second, to evaluate potential risk factors for occurrence of abnormal findings on the EGD. Methods: An observational, retrospective study in which all 232 patients who were cleared to undergo bariatric surgery and who underwent preoperative EGD between 2006 and 2013 were included at a single tertiary dedicated bariatric center for weight loss management. Abnormal findings on screening EGD and medical or surgical management alteration based on the EGD findings were reviewed. Results: Abnormal findings on screening EGD were found in 143 patients (61.6%). Thirty-five patients had medical management altered (15.1%), while four patients (1.7%) had surgical management altered. Being aged >55 years and the presence of gastroesophageal reflux disease were associated with occurrence of an abnormal finding on screening EGD. Conclusions: While abnormalities on preoperative EGD are often found in patients undergoing bariatric surgery evaluation, rarely do the findings change surgical management. Alternative methods for screening for common GI conditions should be considered in appropriate patients.

Bacterial urease and its role in long-lasting human diseases

Urease is a virulence factor found in various pathogenic bacteria. It is essential in colonization of a host organism and in maintenance of bacterial cells in tissues. Due to its enzymatic activity, urease has a toxic effect on human cells. The presence of ureolytic activity is an important marker of a number of bacterial infections. Urease is also an immunogenic protein and is recognized by antibodies present in human sera. The presence of such antibodies is connected with progress of several long-lasting diseases, like rheumatoid arthritis, atherosclerosis or urinary tract infections. In bacterial ureases, motives with a sequence and/or structure similar to human proteins may occur. This phenomenon, known as molecular mimicry, leads to the appearance of autoantibodies, which take part in host molecules destruction. Detection of antibodies-binding motives (epitopes) in bacterial proteins is a complex process. However, organic chemistry tools, such as synthetic peptide libraries, are helpful in both, epitope mapping as well as in serologic investigations.

In this review, we present a synthetic report on a molecular organization of bacterial ureases - genetic as well as structural. We characterize methods used in detecting urease and ureolytic activity, including techniques applied in disease diagnostic processes and in chemical synthesis of urease epitopes. The review also provides a summary of knowledge about a toxic effect of bacterial ureases on human body and about occurrence of anti-urease antibodies in long-lasting diseases.

Rapid (13)C Urea Breath Test to Identify Helicobacter pylori Infection in Emergency Department Patients with Upper Abdominal Pain

INTRODUCTION

In emergency department (ED) patients with upper abdominal pain, management includes ruling out serious diseases and providing symptomatic relief. One of the major causes of upper abdominal pain is an ulcer caused by Helicobacter pylori (H. pylori), which can be treated and cured with antibiotics. We sought to estimate the prevalence of H. pylori infection in symptomatic patients using a convenience sample at a single urban academic ED and demonstrate the feasibility of ED-based testing.

METHODS

We prospectively enrolled patients with a chief complaint of pain or discomfort in the upper abdomen for 1 year from February 2011 until February 2012 at a single academic urban ED. Enrolled subjects were tested for H. pylori using a rapid point of care (13)C Urea Breath Test (UBT) [Exalenz Bioscience]. We compared patient characteristics between those who tested positive versus negative for the disease.

RESULTS

A total of 205 patients with upper abdominal pain were tested over 12 months, and 24% (95% confidence interval: 19% to 30%) tested positive for H. pylori. Black subjects were more likely to test positive than white subjects (28% v. 6%, P < 0.001). Other factors, such as age and sex, were not different between the 2 groups.

CONCLUSION

In our ED, H. pylori infection was present in 1 in 4 patients with epigastric pain, and testing with a UBT was feasible. Further study is needed to determine the risk factors associated with infection, the prevalence of H. pylori in other EDs, the effect of the test on ED length of stay and the costeffectiveness of an ED-based test-and-treat strategy.

Clinical Validation of an Office-Based C-UBT (Heliprobe) for H. pylori Diagnosis in Iranian Dyspeptic Patients

Background. We encountered repeatedly, in our clinical practice, discordant results between UBT and histopathology about H. pylori infection. Goal. To study the diagnostic accuracy of Heliprobe ¹⁴C-urea breath test (¹⁴C-UBT) for detection of H. pylori infection in an Iranian population. Study. We enrolled 125 dyspeptic patients in our study. All of them underwent gastroscopy, and four gastric biopsies (three from the antrum and one from the corpus) were obtained. One of the antral biopsies was utilized for a rapid urease test (RUT), and three others were evaluated under microscopic examination. Sera from all patients were investigated for the presence of H. pylori IgG antibodies. The ¹⁴C-UBT was performed on all subjects using Heliprobe kit, and results were analyzed against the following gold standard (GS): H. pylori infection considered positive when any two of three diagnostic methods (histopathology, RUT, serology) are positive. Results. According to data analysis, the Heliprobe ¹⁴C-UBT had 94% sensitivity, 100% specificity, 93% negative predictive value (NPV), 100% positive predictive value (PPV), and 97% accuracy, compared with GS. Conclusion. The Heliprobe ¹⁴C-UBT is an easy-to-perform, rapid-response, and accurate test for H. pylori diagnosis, suitable for office use.

Cost-effectiveness of six strategies for Helicobacter pylori diagnosis and management in uninvestigated dyspepsia assuming a high resource intensity practice pattern

BACKGROUND

Initial assessment of dyspepsia often includes noninvasive testing for Helicobacter pylori infection. Commercially available tests vary widely in cost and accuracy. Although there is extensive literature on the cost-effectiveness of H. pylori treatment, there is little information comparing the cost-effectiveness of various currently used, noninvasive testing strategies.

METHODS

A Markov simulation was used to calculate cost per symptom-free year and cost per correct diagnosis. Uncertainty in outcomes was estimated using probabilistic sensitivity analysis.

RESULTS

Under the baseline assumptions, cost per symptom-free year was $122 for empiric proton pump inhibitor (PPI) trial, and costs for the noninvasive test strategies ranged from $123 (stool antigen) to $129 (IgG/IgA combined serology). Confidence intervals had significant overlap.

CONCLUSIONS

Under our assumptions for how testing for H. pylori infection is employed in United States medical practice, the available noninvasive tests all have similar cost-effectiveness between one another as well as with empiric PPI trial.

Evaluation and management of dyspepsia

Dyspepsia is a common clinical problem seen by both primary care physicians and gastroenterologists. Initial evaluation should focus on the identification and treatment of potential causes of symptoms such as gastroesophageal reflux disease (GERD), peptic ulcer disease, and medication side effects but also on recognizing those at risk for more serious conditions such as gastric cancer. This manuscript discusses the evaluation and management of dyspepsia including the role of proton-pump inhibitors, treatment of Helicobacter pylori, and endoscopy. Finally, treatment of refractory functional dyspepsia is addressed.

Prevalence of Helicobacter pylori infection among new outpatients with dyspepsia in Kuwait

Background

Testing and treatment for Helicobacter pylori has become widely accepted as the approach of choice for patients with chronic dyspepsia but no alarming features. We evaluated H. pylori status among outpatients with uninvestigated dyspepsia in Kuwait.

Methods

A prospectively collected database for 1035 patients who had undergone ¹³C-urea breath tests (UBT) for various indications was reviewed for the period from October 2007 to July 2009. The status of H. pylori in dyspeptic patients was determined by UBT.

Results

Among the 362 patients who had undergone UBT for uninvestigated dyspepsia, 49.7% were positive for H. pylori (95% CI = 44%-55%) and the percentage increased with age (35.8% at 20-29 years, 95% CI = 25.4% - 47.2%; 59.3% at 30-39 years, 95% CI = 48.5% - 69.5%) (P = 0.013). The prevalence of H. pylori was 42.6% among Kuwaitis (95% CI = 35%-50%) and 57.6% (95% CI = 49.8%-65%) among expatriates (p = 0.004). The prevalence among males was 51.3%, while in females it was 48.6%.

Conclusions

Almost half of the patients with dyspeptic symptoms in Kuwait were positive for H. pylori, though the prevalence varied with age and was higher among expatriates. The American Gastroenterology Association guidelines recommending testing and treatment for H. pylori for patients with uninvestigated dyspepsia should be endorsed in Kuwait.

Helicobacter pylori seropositivity and stool antigen in patients with hyperemesis gravidarum

The objective of this paper is to investigate whether Helicobacter pylori is an etiologic factor in hyperemesis gravidarum. Thirty one patients with hyperemesis gravidarum and twenty nine pregnant controls without hyperemesis gravidarum were included in this prospective study. All pregnant women were examined both for Helicobacter pylori serum immunoglobulin G antibodies (HpIgG Ab), showing chronic infection, and Helicobacter pylori stool antigens (HpSA), showing active gastrointestinal colonization. Chi-square and Student t tests were used accordingly for statistical analysis. Helicobacter pylori seropositivity was 67.7% in the patients with hyperemesis gravidarum and 79.3% in the control group (χ² = 1.02, P = .31). HpSA was detected in 22.6% of patients with hyperemesis gravidarum, whereas 6.9% of patients in the control group. The difference was not statistically significant (χ² = 2.89, P = .08). In this study, no relation was found between Helicobacter pylori and hyperemesis gravidarum. The low social status of women in both groups could be one of the reasons for the high prevalence of Hp infection.

American College of Gastroenterology guideline on the management of Helicobacter pylori infection

Helicobacter pylori (H. pylori) remains a prevalent, worldwide, chronic infection. Though the prevalence of this infection appears to be decreasing in many parts of the world, H. pylori remains an important factor linked to the development of peptic ulcer disease, gastric malignanc and dyspeptic symptoms. Whether to test for H. pylori in patients with functional dyspepsia, gastroesophageal reflux disease (GERD), patients taking nonsteroidal antiinflammatory drugs, with iron deficiency anemia, or who are at greater risk of developing gastric cancer remains controversial. H. pylori can be diagnosed by endoscopic or nonendoscopic methods. A variety of factors including the need for endoscopy, pretest probability of infection, local availability, and an understanding of the performance characteristics and cost of the individual tests influences choice of evaluation in a given patient. Testing to prove eradication should be performed in patients who receive treatment of H. pylori for peptic ulcer disease, individuals with persistent dyspeptic symptoms despite the test-and-treat strategy, those with H. pylori-associated MALT lymphoma, and individuals who have undergone resection of early gastric cancer. Recent studies suggest that eradication rates achieved by first-line treatment with a proton pump inhibitor (PPI), clarithromycin, and amoxicillin have decreased to 70-85%, in part due to increasing clarithromycin resistance. Eradication rates may also be lower with 7 versus 14-day regimens. Bismuth-containing quadruple regimens for 7-14 days are another first-line treatment option. Sequential therapy for 10 days has shown promise in Europe but requires validation in North America. The most commonly used salvage regimen in patients with persistent H. pylori is bismuth quadruple therapy. Recent data suggest that a PPI, levofloxacin, and amoxicillin for 10 days is more effective and better tolerated than bismuth quadruple therapy for persistent H. pylori infection, though this needs to be validated in the United States.

Guidelines for the management of dyspepsia

Dyspepsia is a chronic or recurrent pain or discomfort centered in the upper abdomen; patients with predominant or frequent (more than once a week) heartburn or acid regurgitation, should be considered to have gastroesophageal reflux disease (GERD) until proven otherwise. Dyspeptic patients over 55 yr of age, or those with alarm features should undergo prompt esophagogastroduodenoscopy (EGD). In all other patients, there are two approximately equivalent options: (i) test and treat for Helicobacter pylori (H. pylori) using a validated noninvasive test and a trial of acid suppression if eradication is successful but symptoms do not resolve or (ii) an empiric trial of acid suppression with a proton pump inhibitor (PPI) for 4-8 wk. The test-and-treat option is preferable in populations with a moderate to high prevalence of H. pylori infection (> or =10%); empirical PPI is an initial option in low prevalence situations. If initial acid suppression fails after 2-4 wk, it is reasonable to consider changing drug class or dosing. If the patient fails to respond or relapses rapidly on stopping antisecretory therapy, then the test-and-treat strategy is best applied before consideration of referral for EGD. Prokinetics are not currently recommended as first-line therapy for uninvestigated dyspepsia. EGD is not mandatory in those who remain symptomatic as the yield is low; the decision to endoscope or not must be based on clinical judgement. In patients who do respond to initial therapy, stop treatment after 4-8 wk; if symptoms recur, another course of the same treatment is justified. The management of functional dyspepsia is challenging when initial antisecretory therapy and H. pylori eradication fails. There are very limited data to support the use of low-dose tricyclic antidepressants or psychological treatments in functional dyspepsia.

Comparison of two management strategies for Helicobacter pylori treatment: clinical study and cost-effectiveness analysis

BACKGROUND

First-line proton pump inhibitor-based triple and quadruple therapies for Helicobacter pylori eradication present similar levels of efficacy. Cross-over treatment (quadruple following triple failure, and triple following quadruple failure) seems the most sensible approach to treatment failures, but the two strategies -'quadruple first' versus 'triple first'- have not been previously compared. The aims of our study were to assess the usefulness and the cost-effectiveness of the two treatment strategies.

MATERIAL AND METHODS

Forty-nine out of 344 patients included in a previous study comparing triple therapy - 7 days of omeprazole, amoxicillin and clarithromycin twice a day - with quadruple therapy - 7 days of omeprazole twice a day, plus tetracycline, metronidazole and bismuth subcitrate three times a day - failed initial treatment and were assigned to cross-over therapy. Cure was determined by urea breath test. A decision analysis was performed to compare the two eradication strategies.

RESULTS

Intention to treat cure rates were 46% (10/22 patients; 95% CI 24-68%) for second-line triple therapy and 63% (17/27 patients; 95% CI 42-81%) for second-line quadruple therapy. Per protocol cure rates were 71% and 85%, respectively. Intention to treat cure rates were 87% (95% CI 81-92%) for the 'triple first' versus 86% (95% CI 80-91%) for the 'quadruple first' strategy (p = .87). The 'quadruple first' strategy was more cost-effective. The incremental cost of 'triple first' strategy per person was 19 in the low-cost area and 65 US dollars in the high-cost area.

CONCLUSIONS

The effectiveness of 'triple first' and 'quadruple first' strategies is similar, although the latter seems slightly more cost-effective.

Stool antigen test for the diagnosis of Helicobacter pylori infection: a systematic review

Our aim was to review systematically the diagnostic accuracy of the Helicobacter pylori stool antigen test. Bibliographical searches were performed in several electronic databases and abstracts from congresses up to May 2003. Eighty-nine studies (10,858 patients) evaluated the stool antigen test in untreated patients. Mean sensitivity, specificity, positive predictive value and negative predictive value were 91%, 93%, 92% and 87%, respectively. Analysis of the eight studies (1399 patients) in which pretreatment evaluation of the monoclonal stool antigen test was performed showed better (p < .001) results (96%, 97%, 96% and 97%, respectively), with a clearer distinction between positive and negative results. Thirty-nine studies (3147 patients) evaluated the stool antigen test for the confirmation of H. pylori eradication 4-8 weeks after therapy, with accuracies of 86%, 92%, 76% and 93% for mean sensitivity, specificity, positive predictive value and negative predictive value, respectively. Results were similar when a gold standard based on at least two methods was used. Relatively low accuracy was reported in some posttreatment studies with the polyclonal stool antigen test. However, excellent results (p < .001) were achieved in all the six studies evaluating the monoclonal stool antigen test 4-8 weeks posttreatment. Results evaluating the stool antigen test < 4 weeks posttreatment are contradictory. Proton-pump inhibitors seem to affect the accuracy of the stool antigen test. Sensitivity and/or specificity in patients with gastrointestinal bleeding may be suboptimal. The stool antigen test performs well in children. Finally, the stool antigen test seems to be a cost-effective method.

Diagnosis of Helicobacter pylori infection by stool antigen determination: a systematic review

Recently a new, noninvasive diagnostic test based on the detection of Helicobacter pylori stool antigen (SA) has been developed. The aim of this study was to systematically review the experience on H. pylori SA test for the diagnosis of H. pylori infection. Bibliographic searches were performed in the PubMed database and abstracts from several congresses. A total of 43 studies fulfilled the inclusion criteria and evaluated H. pylori SA test accuracy for the diagnosis of H. pylori infection in nontreated patients. Overall, 4769 patients were included. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) (weighted mean) were, respectively: 92.4% (95% CI = 91-93%), 91.9% (91-92%), 92.1% (91-93%), and 90.5% (90-91%). Therefore the SA test can definitively be considered an accurate noninvasive method for the diagnosis of H. pylori infection in untreated patients. A total of 25 studies including 2078 patients evaluated H. pylori SA test for the confirmation of H. pylori eradication > or = 4 wk after completion of therapy. Sensitivity, specificity, PPV and NPV (weighted mean) were: 88.3% (87-90%), 92% (91-93%), 75.1% (73-77%), and 94.8% (94-96%). Although most studies showed that SA test is an accurate method to confirm H. pylori eradication > or = 4 wk after treatment, these favorable results were not confirmed in other studies. Further investigation is necessary to explain these discrepancies, as well as to clarify the precise time for confirmation of eradication after therapy, the appropriate cutoff point for the SA test, and which factors influence it. Proton pump inhibitors seem to affect the accuracy of SA test, but the negative effect disappears 1-2 wk after stopping treatment. The SA test is technically feasible in patients with upper GI bleeding. although the true diagnostic accuracy in this group of patients remains to be more fully assessed. Finally, the SA test seems to be a highly cost-effective method for the diagnosis of H. pylori infection.