A re-testing range is recommended for (13)C- and (14)C-urea breath tests for Helicobacterpylori infection in China

BACKGROUND: The urea breath test (UBT) is widely used for diagnosing Helicobacter pylori infection. In the Shenzhen Kuichong People’s Hospital, some UBT findings were contradictory to the histology outcomes, therefore this study aimed to assess and compare the diagnostic performance of both (13)C- and (14)C-UBT assays. METHODS: We recruited 484 H. pylori-treatment naïve patients, among which 217 and 267 were tested by the (13)C-UBT or (14)C-UBT, respectively. The cutoff value for H. pylori positivity based on manufacturer’s instruction was 4% delta over baseline (DOB) for the (13)C-UBT, and 100 disintegrations per minute (DPM) for the (14)C-UBT. Gastric biopsies of the antrum and corpus were obtained during endoscopy for histopathology. RESULTS: In patients who were tested using the (13)C-UBT kit, histopathology was positive in 136 out of 164 UBT-positive patients (82.9% concordance), and negative in 46 out of 53 UBT-negative cases (86.8% concordance). For the (14)C-UBT-tested patients, histopathology was positive for H. pylori in 186 out of 220 UBT-positive patients (84.5% concordance), and negative in 41 out of 47 UBT-negative cases (87.2% concordance). While the (13)C-UBT and (14)C-UBT each had a high sensitivity level of 95.1% and 96.9%, respectively, their specificity was low, at 62.2% and 54.7%, respectively. By using new optimal cutoff values and including an indeterminate range (3–10.3% DOB for (13)C-UBT and 87–237 DPM for (14)C-UBT), the specificity values can be improved to 76.7% and 76.9% for the (13)C- and (14)C-UBT, respectively. CONCLUSIONS: The establishment of an indeterminate range is recommended to allow for repeated testing to confirm H. pylori infection, and thereby avoiding unnecessary antibiotic treatment. Trial registration: Chinese Clinical Trial Registry, ChiCTR2000041570. Registered 29 December 2020- Retrospectively registered, http://www.chictr.org.cn/edit.aspx?pid=66416&htm=4 SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13099-021-00435-3.