An inter- and intra-laboratory comparison of breath ¹³CO₂ analysis

Background: ¹³C breath test analysis requires accurate ¹³CO₂ measurements. Aim: To perform a multicentre study to evaluate the repeatability and reproducibility of breath ¹³CO₂ analysis. Methods: Two series of 25 paired randomly coded tubes (each consisting of 23 ¹³CO₂-enriched breath samples and two samples of standard reference pure CO₂ with certified δ¹³C_PDB) were sent to participating centres for ¹³CO₂ measurement. 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.