Lasergestuurde 13C-ureumademtest; een nieuwe non-invasieve detectiemethode voor Helicobacter pylori-infectie

OBJECTIVE: To assess the laser assisted ratio analyser (LARA) system for detection of Helicobacter pylori infection in breath samples. DESIGN: Descriptive. METHOD: Diagnostic gastroscopy with biopsies for histopathology and culture was performed in consecutive dyspeptic patients in the Department of Gastroenterology of the Academic Medical Centre of Amsterdam in January-May 1996. Subsequently, a LARA test was carried out, which measures the degradation by H. pylori of 13C urea using the ratio of 12CO2/13CO2 in the exhaled air. The combination of the results of the examination of gastric biopsies was regarded as the golden standard for the demonstration of H. pylori infection. After this comparison, the cut-off level above which the LARA system demonstrated H. pylori infection was established in the basis of a receiver operator characteristics (ROC) analysis. An area was defined round this value within which the results were inconclusive and outside of which the reliability increased. RESULTS: 208 patients were included in the study; the data of nine of them could not be analysed (CO2 level in the exhaled air too low: 8; withdrawal: 1). The remaining 199 patients were 105 males and 94 females with a mean age of 48 years (range 19-75). Ninety-three of them (47%) were H. pylori positive according to the golden standard. With the breath analysis infection was detected in 86 of them, while in 97 patients breath analysis was correctly negative; it was false-negative in four, false-positive in three and unreliable in nine patients. The sensitivity was 96%, the specificity 97%. The positive and negative predictive values were 97% and 96%, respectively