Evaluation of the (14)C-urea breath test using indigenously produced (14)C-urea capsules and a modified technique for trapping exhaled breath: a pilot study

The carbon urea breath test ((14)C-UBT) is a noninvasive technique used to detect Helicobacter pylori infection in patients presenting with dyspeptic symptoms. The present study was undertaken to determine the efficacy of indigenously produced (14)C-UBT capsules by the Board of Radiation and Isotope Technology, India. Thirty consecutive patients with dyspeptic symptoms were included in the study. After ingestion of capsules, breath samples were collected in a CO2-trapping solution to which a scintillation cocktail was added. After 24 h, the whole sample was counted in a liquid scintillation counter along with a standard of (14)C. The number of disintegrations of (14)C per minute in the breath sample was calculated. The results were compared with histopathological reports. Of 30 patients, 19 were positive and 11 were negative on (14)C-UBT. Histopathological reports confirmed 27 cases as positive and three as negative for H. pylori. Thus, the results of (14)C-UBT were concordant with histopathological results in 22/30 (73.3%) cases. Considering histopathology as the gold standard, the sensitivity, specificity, and positive predictive value of (14)C-UBT using indigenously produced capsules were found to be 70.33, 100, and 100%, respectively. On critical analysis of the discordant results, we observed that six patients had undergone H. pylori eradication therapy exactly 4 weeks before the test. When these six patients were excluded from the analysis, the sensitivity, specificity, and positive predictive value were found to be 90.05, 100, and 100%, respectively, which compared well with the values obtained using the standard procedure. The study demonstrates adequate efficacy of the indigenous methodology in newly diagnosed symptomatic patients with acid peptic disorders. The analyses of the results indicate that the test should be preferably employed after the recommended period of 1 month following completion of eradication therapy.