Comparison of Salivary and Serum Enzyme Immunoassays for the Diagnosis ofHelicobacter pyloriInfection

Abstract

JM Embil, SH Choudhri, G Smart, et al. Comparison of salivary and serum enzyme immunoassays for the diagnosis of Helicobacter pylori infection. Can J Infect Dis 1998;9(5):277-280.Infection with Helicobacter pylori has been established as an important risk factor for the development of peptic ulcer disease, gastritis and gastric cancer. The diagnosis of H pylori infection can be established by invasive or noninvasive techniques. Two noninvasive enzyme immunoassays (EIAs) for antibody detection -HeliSal and Pylori Stat -were compared with histology. Both assays detect immunoglobulin (Ig) G directed against purified H pylori antigen. The test populations consisted of 104 consecutive patients scheduled for upper gastrointestinal endoscopy. Of these patients, 97 (93%) had symptoms compatible with peptic ulcer disease. Saliva and serum were collected simultaneously at the time of endoscopy. Salivary EIA had a sensitivity of 66%, specificity of 67%, positive predictive value of 67% and negative predictive value of 66% compared with the serum EIA, where the results were 98%, 48%, 64% and 96%, respectively. Although the salivary EIA is an appealing noninvasive test, it was not a sensitive and specific assay. The serum EIA also lacked specificity, but was highly sensitive with a good negative predictive value. Although a negative serum EIA rules out H pylori infection, a positive result must be interpreted in the clinical context and confirmed with a more specific measure. elicobacter pylori is a motile, microaerophilic, curved Gram-negative rod which has been established as an important risk factor for the development of peptic ulcer disease (PUD) and gastritis (1). The National Institute of Health, Bethesada, Maryland have recommended that all patients with PUD infected with H pylori should receive antimicrobial therapy because cure of this infection leads to markedly reduced ulcer recurrence rates (1).The diagnosis of H pylori infection can be made either invasively by means of endoscopy and histological analysis of the biopsied tissue or noninvasively by the urea breath test and antibody detection in serum. Enzyme immunoassays (EIAs) that detect immunoglobulin (Ig) G in saliva have been developed as an alternative to the aforementioned techniques (2). Anti-H pylori IgG is found in saliva, and the advantage of the currently available salivary assay for H pylori is its ease of administration. If the salivary EIA is to be an effective noninvasive screening tool for H pylori-induced disease, it must be sensitive (2-6), specific and compare favourably with other already established noninvasive and invasive techniques, such as the urea breath test and serology (7-9). The objectives of this study were to determine the sensitivity, specificity, positive (PPV) and negative predictive values (NPV), and test accuracy of the Helisal (Axcan Pharma) Salivary EIA for diagnosing H pylori in comparison with the 'gold standard' of endoscopic biopsy for histology, as well as with a standard serum EIA (Pylori Stat, Bio-Whittaker, Marylan...

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

“…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. [18] However, these differences can be attributed to several factors such as the type of population studied, decreased saliva fl ow due to pre-endoscopy anxiety, or differences of HP strains. Thus, if endoscopy had not been done, none of the HP-associated DU and very few of the gastritis group would have been missed by either serologic tests.…”