Do patients need to fast for a C-13-urea breath test?

Objective: The C-13-urea breath test (C-13-UBT) is a useful non-invasive method of diag nosing Helicobacter pylori infection. One of its limitations, however, is that patients have to fast for 4 h before testing. We have compared the accuracy of a non-fasting C-13- UBT ((NFC)-C-13-UBT) with a fasting C-13-UBT ((FC)-C-13-UBT) test and against a gold standard. Design: An unblinded prospective crossover study. Methods: H. pylori status was assessed by histology, culture and rapid urease test. Patients were defined as H. pylori positive if two or more tests gave a positive result and negative if all tests were negative. H. pylori status was indeterminate if only one test gave a positive result. Following endoscopy patients had a (FC)-C-13-UBT and then a further (NFC)-C-13-UBT up to 14 days later after eating two slices of toast with jam or honey and tea or coffee. Results: Of the 222 patients recruited to the study, 123 were gold standard H. pylori positive and 94 were negative with five patients having indeterminate status. Compared to this gold standard the (NFC)-C-13-UBT had a 98% sensitivity and 96% specificity and the (FC)-C-13-UBT had a 96% sensitivity and 97% specificity. The (NFC)-C-13-UBT and (FC)-C-13-UBT agreed in 217/222 (98%) cases. Conclusion: Relaxation of the fasting state does not reduce the accuracy of the C-13-UBT, making this test more convenient for patients.