Qualitative and semi-quantitative value of a modified C-13-urea breath test for identification of Helicobacter pylori infection

Objective: The C-13-urea breath test (C-13-UBT) is the method of choice in evaluating the success of therapy for eradication of Helicobacter pylori infection. For reasons of cost efficiency and practicability, urea dose and measurement duration have been reduced and the DOB (delta over baseline) cutoff level with the highest predictive value determined. Further, the efficacy of the modified C-13-UBT as a semi-quantitative test method was evaluated by comparison with histologically determined bacterial infiltration. Methods: In a prospective study, a modified C-13-UBT with reduced urea dose (75 mg) and shortened measurement duration (30 min) was administered to 145 patients. The DOB cutoff with the highest predictive value was determined using relative operating characteristic analysis. Reference methods included histology, bacterial culture and the rapid urease test. The DOB value was compared with the histologically determined grade of bacterial infiltration and the correlation evaluated using the Spearman ranking method. Results: Reduction of the DOB cutoff level from 5.0 parts per thousand to 3.5 parts per thousand led to significant improvement in sensitivity (78.9% vs. 91.2%) and accuracy (88.6% vs. 90.2%) of the C-13-UBT. Only five of 57 infected patients were incorrectly reported as non-infected after modification of the DOB level. In two of three patients in whom histological findings were negative but the 13 C-urease test positive, bacterial growth was observed at culture. The DOB level correlated significantly with histological grade of bacterial infection. Conclusion: The modified C-13-UBT proved to be a sensitive, practicable and cost-effective method for detecting H. pylori infection and permits a semi-quantitative estimation of bacterial infiltration.