To determine whether a shortened 13C urea breath test (13C UBT) (breath collection time of 10 min) is as reliable as the standard assay (30 min).
Two hundred ninety-seven patients (mean ± SD: 53±16 years, 57% female) completed a 13C 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 13C UBT data to determine the optimal cut-off point at each time interval. Sensitivity and specificity of the 13C UBT at all intervals compared with histology and culture and against the standard 30 min interval were determined.
The calculated optimal cut-off points for each time interval (T), expressed as delta over baseline (δ‰), were 3.29 δ‰ at T5, 3.15 δ‰ at T10, 3.42 δ‰ at T15, 3.17 δ‰ at T20, 2.99 δ‰ at T25 and 2.82 δ ‰ at T30. Except at T5, 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 δ‰, the risk of error was still lower than 2.3%. The test at T10 showed 98.6% sensitivity and 98.6% specificity compared with T30. T10 and T30 showed 100% sensitivity and 96% specificity compared with histology and culture.
The 13C 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 δ‰ for the 10 min and 30 min 13C UBT.