Comparison of accuracy between 13C- and 14C-urea breath testing: Is an indeterminate-results category still needed?

Abstract

Helicobacter pylori infection is the leading cause of peptic ulcer disease. The purpose of this study was, first, to assess the difference in the distribution of negative versus positive results between the older 14C-urea breath test and the newer 13C-urea breath test and, second, to determine whether use of an indeterminateresults category is still meaningful and what type of results should trigger repeated testing. Methods: A retrospective survey was performed of all consecutive patients referred to our service for urea breath testing. We analyzed 562 patients who had undergone testing with 14C-urea and 454 patients who had undergone testing with 13C-urea. Results: In comparison with the wide distribution of negative 14C results, negative 13C results were distributed farther from the cutoff and were grouped more tightly around the mean negative value. Distribution analysis of the negative results for 13C testing, compared with those for 14C testing, revealed a statistically significant difference between the two. Within the 13C group, only 1 patient could have been classified as having indeterminate results using the same indeterminate zone as was used for the 14C group. This is significantly less frequent than what was found for the 14C group. Discussion: Borderline-negative results do occur with 13C-urea breath testing, although less frequently than with 14C-urea breath testing, and we will be carefully monitoring differences falling between 3.0 and 3.5 %D. 13C-urea breath testing is safe and simple for the patient and, inmost cases, provides clearer positive or negative results for the clinician.