Screening dyspeptic patients for Helicobacter pylori prior to endoscopy: laboratory or near-patient testing?

Abstract

Background: It is unclear whether near-patient whole-blood diagnostic tests for Helicobacter pylori are of comparable accuracy to laboratory based ELISA for screening of dyspeptic patients prior to endoscopy.

Aim: To compare two ELISA and two whole-blood tests in order to determine whether near-patient H. pylori diagnostic tests are an acceptable alternative to laboratory based ELISA tests for screening of dyspeptic patients prior to endoscopy.

Method: One hundred and seven consecutive patients with dyspepsia (median age, 32 years; range, 16-45 years) were evaluated with Helico-G ELISA, Hmcap ELISA and Helisal whole-blood tests. A further 111 dyspeptic patients (median age, 51 years; range, 16-96 years) were evaluated with the Immunocard whole-blood test only. The 'gold standard' for infection was based on histology and the rapid urease test (CLO).

Results: Compared to the Helico-G test, both near-patient tests had a higher false negative rate (23-37% vs 5%, P< 0.003), and lower sensitivity and negative predictive value. The Immunocard had a higher specificity than did the Helisal (87% vs 63%, P=0.006); otherwise both near-patient whole-blood tests had similar performance. At a sensitivity of 95%, the Hmcap ELISA was more specific than the Helico-G ELISA (75% vs 67%) and had fewer false positives (25% vs 32%). The near-patient tests would wrongly classify up to 40% H. pylori positive dyspeptic patients and exclude them from endoscopy, compared to 5-6% for ELISA.

Conclusions: Near-patient whole-blood H. pylori diagnostic tests are less accurate and thus not an acceptable alternative to laboratory based ELISA tests.