An inter- and intra-laboratory comparison of breath ¹³CO₂analysis.

Background: ¹³C breath test analysis requires accurate ¹³CO₂measurements.
Aim: To perform a multicentre study to evaluate the repeatability and reproducibility of breath ¹³CO₂analysis.
Methods: Two series of 25 paired randomly coded tubes (each consisting of 23 ¹³CO₂-enriched breath samples and two samples of standard reference pure CO₂with certified δ ¹³C(PDB)) were sent to participating centres for ¹³CO₂measurement. Each series of tubes was analysed 10 days apart. The repeatability and reproducibility of ¹³C measurements was assessed by Mandel's k and h statistics.
Results: Twenty-two centres participated in the study: 18 showed good inter- and intra-laboratory variability, whilst four showed abnormally high inter- or intra-laboratory variability. Breath test results were also significantly affected by the accuracy of the ¹³C analytical procedures.
Conclusions: A low accuracy of ¹³C measurements may significantly affect the results of breath tests, leading to inappropriate clinical decisions. Standardization of ¹³C analysis is required to guarantee optimal ¹³C measurements and accurate ¹³C breath test results.