Evaluation of Accuracy and Feasibility of a New-Generation Ultra-Rapid Urease Test for Detection of Helicobacter pylori Infection

Abstract

Helicobacter pylori (Hp) infection can be diagnosed by invasive and noninvasive methods, and, among the former, Rapid Urease Tests (RUTs) are an important option. Accuracy and rapidity of results are fundamental for RUTs. The aim of the study is to prospectively evaluate the sensitivity, specificity and time to positivity of a new-generation ultra-rapid urease test (iNatal duo test) for Hp detection and compare the results with other available RUTs [CLO Test (Campylobacter-Like Organism Test), CP Test (Campylobacter pylori Test) and Pronto Dry]. Gastric biopsies were taken in consecutive patients undergoing upper endoscopy: two in the antrum and two in the body for histology, and one in the antrum and one in the body for each RUT. RUTs were read at 1, 5, 15, 30 and 60 min, 3 h and 24 h after biopsy insertion into the reagent. Histology was considered as “gold standard”. The performance of the tests was evaluated in patients not taking proton pump inhibitors (PPI) (n = 924) by calculation of sensitivity, specificity and positive and negative predictive value. Agreement rate (κ) for every RUT and histology was calculated and compared. The performance of the iNatal duo test was also tested in a subgroup of patients taking PPI (n = 198). Hp was positive in 225/924 patients (24.3%) not taking PPIs and in 56/198 (28.3%) who were taking PPIs. The iNatal duo test was more sensitive than the other RUTs for detecting Hp at every time point. The sensitivity at 5 min was 96.2% in patients not taking PPIs and 92.2% in patients taking PPIs. κ with histology was higher for the iNatal duo test than any other RUT (at 30 min: iNatal duo 0.99, CLO 0.60, CP 0.78, Pronto 0.85, at 15 min: iNatal duo 0.99, CLO 0.46, CP 0.63, Pronto 0.71). In a prospective study, the iNatal duo test demonstrated high accuracy and rapidity for Hp detection, both in patients with and without PPI therapy. This new generation of ultra-rapid urease test could be useful for the rapid and correct management of patients undergoing upper GI endoscopy for suspected Hp infection.