Utilidad de la detección de antígenos de Helicobacter pylori en heces en el diagnóstico de infección y en el control de la erradicación tras el tratamiento

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.

Comparison of stool immunoassay with standard methods for detection of Helicobacter pylori infection in patients with upper-gastrointestinal bleeding of peptic origin

OBJECTIVE

To assess the accuracy of the determination of Helicobacter pylori infection by a stool immunoassay in patients with upper-gastrointestinal bleeding (UGB) of peptic origin, in comparison with the routine histological study, serology, rapid urease and 13C-breath tests.

METHODS

Sixty-eight patients with endoscopically proven UGB of peptic origin were included. The presence of H. pylori was considered when observed on histology or, if negative, by the positive indications of two of the remaining tests (serology, rapid urease,13C-breath test). The accuracy of stool immunoassay was estimated according to results obtained with other diagnostic methods.

RESULTS

Lesions causing gastrointestinal bleeding were 49 duodenal ulcers, 11 gastric ulcers, six pyloric channel ulcers, 13 acute lesions of the gastric mucosa, and 16 erosive duodenitis. H. pylori infection was present in 59 (86.76%) patients. Forty-one patients had received nonsteroidal anti-inflammatory drugs. The sensitivity and specificity of the diagnostic methods were 47.5% and 100% for the rapid urease test, 93% and 87.5% for the breath test, 86.4% and 77.7% for serology, 89.4% and 100% for histology, and 96.6% and 33.3% for the stool test.

CONCLUSIONS

The detection of H. pylori antigen in stools in patients with UGB of peptic origin has a good sensitivity (96.6%) but a low specificity (33.3%) for the diagnosis of H. pylori infection, which probably makes this test an inadequate tool in this setting if utilized alone.

Evaluación de un test rápido (ImmunoCard STAT! HpSA) para la detección de Helicobacter pylori en heces

INTRODUCTION

The use of a rapid diagnostic technique may be extremely useful for the management of Helicobacter pylori infection. A new immunochromatographic in-office test (ImmunoCard STAT! HpSA, Meridian Diagnosis Inc, Cincinnati, Ohio, USA) for the detection of H. pylori in feces has recently become available. The aim of the present study was to evaluate the diagnostic reliability and reproducibility of the ImmunoCard STAT! HpSA test in patients with dyspepsia.

PATIENTS AND METHODS

Sixty-three dyspeptic patients were enrolled. H. pylori status was determined by CLO-test and Giemsa staining of antral biopsy. Patients with a positive result for both tests were considered infected and those with a negative result for both tests were considered not infected. Fecal H. pylori antigen was tested twice by ImmunoCard STAT! HpSA. The sensitivity, specificity, positive predictive value and negative predictive value of each determination were calculated. The concordance between the two determinations was evaluated using Kappa statistics.

RESULTS

Of the 63 patients, 46 were infected by H. pylori. Sensitivity, specificity and positive and negative predictive values were 89-91%, 86-93%, 96-98% and 72-75%, respectively. The correlation coefficient between determinations was 0.845.

CONCLUSION

The new ImmunoCard STAT! HpSA test shows good sensitivity and reproducibility. Therefore, it could be highly useful in the management of H. pylori infection.

Comparison of two enzyme immunoassays for the assessment of Helicobacter pylori status in stool specimens after eradication therapy

OBJECTIVES

Assessment of Helicobacter pylori antigen in stool specimens has recently been proposed as a valid method for the noninvasive detection of H. pylori infection, especially as posttreatment control. After the development of an enzyme immunoassay based on polyclonal antibodies (Premier Platinum HpSA) a monoclonally based test has recently been developed (FemtoLab H. pylori). The aim of the present study was to assess the diagnostic accuracy of both tests in adult patients undergoing H. pylori eradication therapy.

METHODS

Stool samples were collected and the 13C-urea breath test performed in 148 patients (79 females and 69 males aged 21-75 yr) 4-6 wk after eradication therapy. The FemtoLab H. pylori and Premier Platinum HpSA tests were performed in accordance with the manufacturers' protocols. A receiver operator characteristics analysis was performed to define the optimal cutoff value on the basis of the results of the 13C-urea breath test.

RESULTS

H. pylori eradication was successful in 113 of the 148 patients (76%). After adjusting the cutoff, the sensitivity of FemtoLab H. pylori was found to be higher than that of the Premier Platinum HpSA (94.3% vs 80.0%, ns). Specificity, positive predictive value, and negative predictive value of the two tests were comparable (93.8% vs 95.6%, 82.8% vs 85.2%, and 98.1% vs 93.8%, respectively).

CONCLUSIONS

The new stool antigen test (FemtoLab H. pylori) is an excellent tool for diagnosing H. pylori infection after eradication therapy, and its accuracy is comparable with that of the Premier Platinum HpSA. Adjustment of the cutoff after H. pylori eradication therapy increases the overall accuracy.

[Stool antigen test for initial Helicobacter pylori diagnosis and for confirmation of eradication after therapy]

BACKGROUND

: Recently, a new diagnostic method based on the detection of Helicobacter pylori antigen in stools (HpSA) has been developed. Our aim was to prospectively evaluate the accuracy of HpSA both in the initial diagnosis of H. pylori infection and in the confirmation of the eradication after treatment.

PATIENTS AND METHOD

Thirty dyspeptic patients were prospectively evaluated. During endoscopy, biopsies for histology and rapid urease test were obtained, and a 13C-urea breath test was performed. HpSA was determined by radioimmunoassay(Premier Platinum HpSA). Infected patients were administered H.pylori eradication treatment, and breath test and HpSA were performed again 4 weeks after finishing the therapy. Gold standard for H. pylori infection pre-treatment was based on rapid urease test, histology and breath test, whereas 13C-urea breath test was considered the post-treatment gold standard.

RESULTS

Pre-treatment H. pylori prevalence was 57%. Eradication was achieved in 85% of patients. The area under ROC curve for HpSA pre-treatment was 0.98. Cut-off points with best pre-treatment diagnostic accuracy were those between 0.10 and 0.12: positive likelihood ratio (LR), negative LR, 0.06; 94% sensitivity (95% CI, 73-99%),100% specificity (75-100%), 100% positive predictive value (81-100%)and 93% negative predictive value (66-100%). After treatment,the area under ROC curve was 1, and all cut-off points between 0.10 and 0.18 had 100% diagnostic accuracy. HpSA levels decreased from 0.94 (0.9) to 0.08 (0.02) (p < 0.01) in patients withH. pylori eradication success.

CONCLUSIONS

HpSA test can be considered an accurate, non-invasive method for the diagnosis of H. pylori infection both inuntreated patients and in the confirmation of H. pylori eradication after treatment.

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.