The accuracy and repeatability of breath test in the diagnosis of Helicobacter pylori (HP) infection is debatable. Although it has been shown that storage for long periods does not affect the analysis results, no data are available, on the effect of repetitive testing.
Our aim was to evaluate the repeatability of the analysis of the breath samples.
A total of 202 breath samples were collected in duplicates, before and after administration of 75 mg urea-13C dissolved in 50 ml of orange juice and the results were expressed as delta 13CO2 (d13CO2). The cut-off value was 3.5 parts per thousand. Each sample was analyzed in a mass spectrometer 7 days after collection and in intervals of 7 days for the duration of additional 3 weeks. The precision calculation was based on the comparison of the d13CO2 obtained in the three consecutive weeks following the first run to the d13CO2 obtained in the first run. The samples were stored at room temperature.
In the second run, 200 out of the 202 (99%) samples were tested positive for HP and the precision of the d13CO2 was 98.6%. In the third run, 197 out of the 202 (97.52%) samples tested positive and the precision was 99.2%. In the fourth and final run 196 out of the 202 (97%) samples tested positive and the precision was 96.7%.
We conclude that short term storage of 1 month, does not affect sample stability and the results of HP diagnosis for up to three consecutive repeats.
