PROSPECTIVE COMPARISON OF COMMERCIALLY AVAILABLE RAPID UREASE TESTS FOR THE DIAGNOSIS OF HELICOBACTER-PYLORI

Background: Rapid urease testing is the initial endoscopic test of cho ice for the diagnosis of Helicobacter pylori. Determination of the rel ative diagnostic yields and times to a positive test for the different rapid urease tests is important for endoscopists. We compared three c ommercially available tests using histologic examination and culture a s a gold standard. Methods: Patients undergoing upper endoscopy had si x biopsy specimens taken from the antrum and six from the body with a large-channel biopsy forceps. Each set of six specimens was divided as follows: one each for CLOtest, Hpfast, and Pyloritek rapid urease tes ts; one for culture; and two for histologic examination (H&E, Genta). All tests were read every 15 minutes for 1 hour; the final reading for Pyloritek was at 1 hour. CLOtest and Hpfast were also read at 4 hours and 24 hours. Results: One hundred seventy-th ree sets of biopsy spec imens from 87 patients were evaluated; 98 (57%) of the 173 sets were p ositive for ii. pylori by histologic examination and/or culture. The m ean and median times to a positive test were significantly less for Py loritek (0.5 +/-: 0.02 hour and 0.5 hour) than for CLOtest (2.0 +/- 0. 6 hour and 0.75 hour) or Hpfast (2.2 +/- 0.6 hour and 0.5 hour). The s ensitivities at the final readings were similar among the three tests (CLOtest: 93%; Hpfast: 88%; Pyloritek: 89%), but sensitivities at 1 ho ur were significantly better for Pyloritek (89%) than for CLOtest (71% ) or Hpfast (66%). At 4 hours, sensitivities for CLOtest and Hpfast im proved significantly and were not significantly different from those o f Pyloritek. Specificities were 99% to 100% at all times for all three tests. Conclusion: The three rapid urease tests, CLOtest, Hpfast, and Pyloritek, provide comparable results, with sensitivities around 90% and specificities around 100%. The Pyloritek becomes positive more rap idly than the CLOtest or Hpfast. If a reading is desired within 1 hour , the Pyloritek provides a greater sensitivity than the CLOtest or Hpf ast without any sacrifice in specificity.