(13)C-Urea breath test threshold calculation and evaluation for the detection of Helicobacter pylori infection in children

BACKGROUND: The (13)C-urea breath test (UBT) is performed in adults and children with epigastric pain for non-invasively diagnosing a suspected H. pylori infection. Criteria for UBT interpretation have not been generally agreed on and test reliability has not been established in children of different ages. This study aimed at identifying reliable UBT thresholds in children by using 251 UBTs in conjunction with reference histology and by analyzing 1232 UBTs. METHODS: At baseline and 30 and 60 minutes after the administration of 75 mg (13)C-urea to children and adolescents (0.25 to 18 years of age), the differences (Δ) of (13)CO(2)/(12)CO(2) ratio in exhaled air (δ) were determined by mass spectrometry. UBT Δδ value thresholds were calculated in random subgroups and evaluated in complementary subgroups using logistic regressions on reference histology or bimodal distribution analyses of Δδ values from UBTs alone. RESULTS: Δδ values were higher (median, 15.4‰) in positive (133/251, 53 %) than in negative histology (2.4‰). At 30 minutes, the calculated cut-off was 5.3‰ (mean regression determination R(2) = 0.91), and sensitivity (0.95), specificity (0.97), positive (0.97) and negative predictive values (0.95) were higher than at 60 minutes (threshold 6.8‰, R(2) = 0.85). Similar thresholds resulted from UBTs analysis (5.8‰ and 6.2‰) when sensitivity and specificity were maximized (concordance probabilities, 0.99 and 0.99). There was no systematic age effect. CONCLUSIONS: In children, (13)C UBT cut-offs were obtained and specially validated, entailing high accuracy of non-invasively testing for gastric H. pylori infection.