High sensitivity and specificity of a laboratory-based serological test, pylori DTect ELISA, for detection of Helicobacter pylori infection

A number of commercial ELISA kits are now available for detection of Helico bacter pylori infection. Generally, whereas the manufacturers have claimed high sensitivity and specificity, independent studies have often failed to confirm the results. The aim of this study was to independently evaluate th e pylori DTect ELISA, a commercial kit for detection of H. pylori infection , in Australian patients with dyspepsia and reflux symptoms. Two hundred an d nine consecutive patients (102 males and 107 females, mean age 52.8 years ) who were referred for endoscopy due to upper gastrointestinal symptoms, b ut had not received anti-H. pylori therapy were enrolled. A 10 mi, blood sa mple was obtained from each subject and used to evaluate the kit. The absor bance index (AI) was calculated from the mean of two readings of optical de nsity (OD) of each serum sample. Eight biopsies from the gastric antrum (x3 ), body (x2), fundus (x2), and incisura (x1) were obtained from each patien t for CLO-testing (x1), culture (x3), and histological examination (x4) for H. pylori. Overall, 84 (40.2%) patients were infected with H. pylori as de termined by the biopsy-based "gold standard." The AIs ranged from 0 to 1.86 ; 0.12 to 1.86 in H. pylori positive patients and 0 to 1.49 in negative pat ients. The pylori DTect ELISA obtained an accuracy of 94 to 95% under Al ra nges between 0.20 to 0.40, with the highest accuracy being 95% under AIs of 0.25 and 0.35. An AI of 0.25 was recommended as the best cut-off Al, with a sensitivity of 96.4%, specificity of 93.6%,positive predictive value of 9 1% and negative predictive value of 97.5%. It is concluded that the pylori DTect ELISA is accurate for detecting H. pylori infection in patients with dyspepsia and reflux symptoms in Australia, when an Al of 0.25 is taken as the cut-off value. (C) 2000 Elsevier Science Inc. All rights reserved.