Abstract
AIM: To determine whether a shortened (13)C urea breath test ((13)C UBT) (breath collection time of 10 min) is as reliable as the standard assay (30 min). METHODS: Two hundred ninety-seven patients (mean +/- SD: 53+/-16 years, 57% female) completed a (13)C UBT. Breath samples were obtained at baseline and at 5 min intervals up to 30 min. Sixty-seven patients also underwent endoscopic biopsy. Cluster analysis was performed on the (13)C UBT data to determine the optimal cut-off point at each time interval. Sensitivity and specificity of the (13)C UBT at all intervals compared with histology and culture and against the standard 30 min interval were determined. RESULTS: The calculated optimal cut-off points for each time interval (T), expressed as delta over baseline (delta/1000), were 3.29 delta/1000 at T(5), 3.15 delta/1000 at T(10), 3.42 delta/1000 at T(15), 3.17 delta/1000 at T(20), 2.99 delta/1000 at T(25) and 2.82 delta/1000 at T(30). Except at T(5), the risk of false-positive and false-negative test results at each time interval was lower than 2.3% using these cut-off points. When replacing the cut-off points with 3.0 delta/1000, the risk of error was still lower than 2.3%. The test at T(10) showed 98.6% sensitivity and 98.6% specificity compared with T(30). T(10) and T(30) showed 100% sensitivity and 96% specificity compared with histology and culture. CONCLUSIONS: The (13)C UBT is an accurate, noninvasive test, even when the breath sample interval is reduced to 10 min. The present study confirms the validity of a cut-off point of 3.0 delta/1000 for the 10 min and 30 min (13)C UBT.