Diagnostic accuracy of the 13C-urea breath test in children:: Adjustment of the cut-off value according to age

Background and Aims: The C-13-urea breath test (C-13-UBT) is a reliable non-invasive method of diagnosing Helicobacter pylori infection in adults and children. However, only a few validation studies have been performed on the C-13-UBT in very young children. The purpose of the present study was to evaluate the diagnostic accuracy of the C-13-UBT according to age, and to determine the optimal cut-off value in children. Methods: A total of 307 C-13-UBT were performed in 274 children. All were compared with the results of endoscopic biopsy-based methods to confirm H. pylori infection. Seventy-five milligrams of C-13-urea was ingested without a test meal. Two breath samples were collected at 0 and 30 min. The optimal cutoff value of the C-13-UBT was assessed by determining the sensitivity, specificity, false negative, and false positive results, at cut-off values ranging from 2.0 to 10.0 parts per thousand. Results: The delta over baseline (DOB) values of the C-13-UBT showed a significant negative correlation with age in both the H. pylori-positive group (r = -0.309; P = 0.005) and the H. pylori-negative group (r = -0.162)- P = 0.015). High false positive results and low specificity were noted in children aged 6 years or less compared with children older than 6 years at a cut-off value of 4.0 parts per thousand (false positives 8.3% vs 0.85%, specificity; 89.8% vs 98.8%). After adjusting the cut-off value, the optimal cut-off values were found to be 4.0 parts per thousand in children older than 6 years and 7.0 parts per thousand in children aged 6 years or less. Conclusions: The cut-off value of the C-13-UBT recommended regardless of age must be adjusted in preschool children to reduce the false positive results. (C) 2004 Blackwell Publishing Asia Pty Ltd.