Evaluation of a new formulation CLOtest

Background and Aims The CLOtest® and other rapid urease detection kits are widely used in the endoscopic diagnosis of Helicobacter pylori. A new formulation CLOtest has been developed with the goal of obtaining a positive result more rapidly. The aims of this study were to validate the sensitivity and specificity of the new test and compare the time taken for a positive result to be visible in both the new and standard CLOtest. Methods Patients presenting for endoscopy at three Western Australian hospitals were prospectively enrolled. Gastric mucosal biopsies were obtained for the standard and new CLOtest and for histology. Grading of color change was conducted by staff blinded to the type of CLOtest used and conducted according to a standardized color chart. Helicobacter pylori status was defined by the combination of a positive standard CLOtest and histology, against which the new CLOtest was compared. Results were obtained at 1, 3 and 24 h, and at one center, at 10 min intervals for the first hour. Results Three hundred and thirty-five patients were enrolled. Eighty-eight Helicobacter pylori-positive individuals were identified. At 24 h, the new test correctly identified all 88, with one false-positive result (sensitivity 100%, specificity 99.6%). At 1 h, sensitivity was 93% with a number of early false-positive results reducing specificity to 96%. Compared to the current CLOtest, the new formulation became positive faster at 20 min (P = 0.001, n = 51), but was similar at 1 h (P = 0.06, n = 88) and equivalent at 3 h. Conclusions The new formulation CLOtest is sensitive and specific, with a trend to give early positive results more quickly, although accuracy at 3 and 24 h is the same.