Comparison Betwen 15 and 30 Minute Sampling Interval for C-Urea Breath Testing

¹³C Urea breath testing is a non-invasive and accurate method for diagnosing active H. pylori infection. Sensitivities and specificities of 90–95% are found when the δ ¹³CO2 levels at baseline and 30 minutes post ingestion of ¹³C urea are measured.

Aim: To determine whether ¹³C UBT accuracy is reduced when the sampling interval is shortened from 30 to 15 minutes.

Breath samples were analysed at 15 minutes and 30 minutes by an infrared Isotope detection (Wagner Analysen Technik Vertriebs analyser). The UBT was taken to be negative if δ ¹³CO2 <2.4, „grey area“ if between 2.4–3.9 and positive if >3.9.

Results: 120 patients had 15 and 30 minute samples taken. The two results were the same in 117 (97.5%) patients, 88 (73.3%) patients having both negative and 29 (24.16%) having both positive. 3 patients had differing results. 2 of these had a positive result at 15 minutes (ratio of 5.7 and 4.6) and a negative result (-0.2 and 1.5) at 30 minutes. The third had a „grey zone result“ (3.0) at 15 and positive (4.0) at 30 mins. On repeat testing the first two remained negative at 15 and 30 minutes and the third remained positive.

Statistical analysis with paired t-test showed a mean difference of 0.1175 (SEM 0.358) and no significant difference (p=0.744) between the readings obtained at 15 and 30 minutes.

Conclusion: The ¹³CUBT remains an accurate test even when the sampling interval is halved. This has advantages for patient acceptance and the GI unit management.