Evaluation of Commercial Immunoassays for Detection of Antibody against Helicobacter pylori in Thai Dyspeptic Patients

Abstract

The performance of five immunoassays for detection of immunoglobulin G antibody against Helicobacter pylori in 191 dyspeptic patients was evaluated. The sensitivities, specificities, accuracies, positive predictive values, and negative predictive values ranged from 86.32 to 97.89%, 57.95 to 72.22%, 77.02 to 83.76%, 71.54 to 77.42%, and 83.33 to 96.23%, respectively. The immunoglobulin A test kit also gave a high sensitivity and negative predictive value (95.79 and 91.40%, respectively), while the specificity was relatively low (51.14%).Serological assay for Helicobacter pylori antibody is a noninvasive method to detect H. pylori infection. It has been reported to have sensitivity and specificity in predicting the status of H. pylori infection in untreated patients as accurately as invasive tests (11,12). However, it has been suggested that serological tests for H. pylori should be locally validated (7), because assays validated in one region may yield variable diagnostic performances in others. These variations may be attributed to many factors, including the source of antigen used, the prevalence of infection in each population studied, and the reference method used to determine true H. pylori infection status. Therefore, reevaluation is needed before implementing a test in different populations. In Thailand, the seroprevalence of H. pylori infection has been reported to be higher than that in industrialized countries (10), and commercially available enzyme immunoassay (EIA) test kits have been reported to have lower sensitivities and specificities compared to in-house EIAs in Thai dyspeptic patients (1). We therefore evaluated the performance of five commercial test kits for detecting of immunoglobulin G (IgG) A total of 191 patients (57 males and 134 females; age range, 16 to 83 years [mean, 39 years]) were studied. Endoscopy was performed in all patients, and 183 (95.81%) of them were diagnosed as having nonulcer dyspepsia while the remaining 8 patients (4.19%) had a duodenal ulcer. Patients who received antibiotic therapy, bismuth treatment, or a proton pump inhibitor or H 2 blocker within 1 month prior to the study were excluded. Written informed consent was obtained from all patients before the study. Five milliliters of clotted blood was obtained on the day of endoscopy. Sera were kept at Ϫ20°C until analyzed. The biopsy specimens from the antrum and stomach body were obtained for rapid urease (CLO) test and histological and cultural examination. All the tests were performed according to the manufacturer's instructions and without the knowledge of the status of the patient's infection. The results of these examinations were described previously (4).In this study, a patient was considered infected with H. pylori when either culture was positive or both rapid urease (CLO) test and histological analysis were positive.Statistic analyses for sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were calculated against the status of H. pylori infection. As shown in Table...

Comparison of the performance of serological kits for Helicobacter pylori infection with European and Asian study populations

“…The performance of an earlier version of this kit was reported to be less than optimal with a Chinese population [7]. However, the current version of the kit showed the same high degree of sensitivity with Thai dyspeptic patients [18] as found in the present study. In the Thai study, all the kits tested had a low specificity, but these determinations suffered from the difficulties entailed when trying to identify true‐negatives, especially in an Asian setting.…”

Comparison of enzyme immunoassays detecting Helicobacter pylori specific IgG in serum and saliva with endoscopic and biopsy findings in patients with dyspepsia

“…19 This trend could also have arisen from possible strain cross-reactivities, sampling errors, differences in defi ning the cut-off values or denial of some patients with normal endoscopy or recent consumption of drugs. [1,19,20] Interestingly, we found no signifi cant difference in the quantity of antibody in either serum or saliva between the normals and those with gastritis or duodenal ulcers [ Figure 3] but a signifi cant difference in the prevalence of these antibodies was observed between the normal group and patients with DU (P = 0.0001 and 0.0015 for serum and saliva, respectively). This supports the usefulness of these tests in detecting HP-associated DU patients and contrasts previous fi ndings which suggested that serum IgG assays were much better than saliva IgG in detecting such patients.…”

“…[15] The present study compared the performance of serum and saliva HP-specifi c IgG serology to antral biopsy histopathology, which is considered one of the gold standard methods for HP detection in a population with high prevalence of HP infection. [1,16] The performance of both serum and saliva immunoassays were concordant with the detection of HP in biopsies from patients with DU and approaches the fi ndings in patients with gastritis. These results are similar to previous reports, which also documented the good sensitivity and specifi city of these assays, [6,17] but a recent report from Canada demonstrated a low sensitivity and specifi city of the saliva ELISA test.…”

“…[1] Recent studies of a number of serologic tests currently available for diagnosing HP infection seem to indicate that none of them is ideal and therefore, the performance characteristics of any of these tests should be carefully considered prior to their utilization in a given setting. [2,3] For quick offi ce evaluation of dyspepsia and population-based studies, a simple, rapid, reliable and an inexpensive test is highly desirable.…”

Frequency of H. pylori Antibodies among Patients with Gastrointestinal Symptoms Attending Khartoum Teaching Hospital- Sudan

“…The most frequent used diagnostic laboratory techniques are culture, stained smears, urease test, PCR assay, Western immunoblotting and histopathological examination of biopsy specimens [10,11]. However, these methods necessitate obtained gastric biopsy materials by an endoscopic invasive procedure [12]. Besides, cultural methods are time-consuming and show low sensitivity [11].…”