A multicentre evaluation of the laser assisted ratio analyser (LARA): A novel device for measurement of (CO2)-C-13 in the C-13-urea breath test for the detection of Helicobacter pylori infection

Background: The laser assisted ratio analyser (LARA) was developed as a nov el device to measure (CO2)-C-13 in the urea breath test for the detection o f H. pylori infection. The analyser was tested in a prospective multicentre study in 444 patients in North America (Phase 1) followed by second study involving 160 patients (Phase 2). Methods: Patients undergoing endoscopy for clinical indications had antral and gastric biopsies taken for histological examination, culture and CLO te st. One hour after endoscopy, a baseline breath sample was obtained, 100 mg of C-13-urea were ingested and breath samples were obtained at 30 and 60 m in post ingestion. Data obtained with the LARA were compared with the resul ts of culture, rapid urease testing and central pathology in two different combinations {reference standards}. The study was conducted in two phases: in Phase 2, a modification was made to the LARA that improved the removal o f water vapour from the breath sample. Results: In Phase I, data from 331 patients were analysed using a cut off o f (delta) 7.8 +/- 0.8, the sensitivity of the method was 91.7% and the spec ificity was 86.5%, using the reference standard of 2 of 3 tests (CLO, cultu re or histology) being positive. Positive and negative predictive values we re, respectively, 85.2% and 92.5%. In Phase 2 of the study, 160 patients we re enrolled and 141 patients were analysed using the same standards. We use d the same reference standards but with a cut off of (delta) 6.1 +/- 0.6. T he sensitivity and specificity increased to 96.8% and 98.6%, respectively. Positive and negative predictive values were, respectively, 98.4% and 97.3% . The detection rates for H. pylori were similar in patients with peptic ul cer or H. pylori associated gastritis. Conclusions: The LARA provides an accurate noninvasive means of detecting ( CO2)-C-13 in the C-13-urea breath test for H. pylori in a multicentre clini cal environment that compares well with invasive 'gold standard' methods.