REPRODUCIBILITY OF THE C-14 UREA BREATH TEST REPEATED AFTER 1 WEEK

Objectives: The aim of this study was to determine the numerical and c ategorical reproducibility of the C-14 urea breath test in a routine c linical setting. Background: The C-14 urea breath test is used for dia gnosis of Helicobacter pylori infection and is regarded by some enters as the gold standard. Methods: In 140 referrals, duplicate tests were performed 1 wk apart. Eighteen patients were excluded because they ha d taken antibiotics or had changed medication that could influence the gastric urease activity between the tests. Results: The limits of agr eement between the repeated tests were 45-234%, Hence, the numerical r esult of a repeated test was 95% likely to differ from the first with a factor of approximately two or less. However, when patients were cla ssified as ''positive'' or ''negative'' according to our previously de termined cut-off limit, only three patients were discordantly classifi ed by the two tests. The observed agreement between the tests was 98%, and the chance-corrected proportional agreement (kappa) was 95%, whic h is far better than that reported for the histological diagnosis of g astric H. pylori infection. Conclusion: The diagnostic reproducibility of the urea breath test was very good.