RESUMO
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.