Limited comparability of creatinine assays in patients with liver cirrhosis and their impact on the MELD score

Background & aim: Patients with end-stage liver disease require valid estimations of mortality for organ allocation and risk stratification. The model of end-stage liver disease (MELD) score is used for this purpose in most countries and incorporates bilirubin, International Normalized ratio, and creatinine. The aim of this study was to evaluate the comparability of creatinine results from different routine assays in the serum samples of patients with liver cirrhosis. Methods: Residual material from 60 serum samples was available from patients in different stages of liver cirrhosis. Four centers participated; each center analyzed the samples with Jaffe-based and enzymatic routine assays in parallel. In addition, an accredited calibration laboratory certified the panel of samples by an internationally accepted reference measurement procedure (RMP) based on isotope dilution mass spectrometry (ID-MS). This method served as the independent reference. Results: All routine methods displayed a high correlation to the RMP (r >= 0.937, p < 0.001). Two enzymatic and two Jaffe-based methods provided results that were all within a +/- 20% range of the RMP. The other methods showed deviations > 20% in up to 27% of the samples. The enzymatic methods were systematically lower, whereas the Jaffe-based methods were systematically higher (p < 0.001). The resulting MELD scores differed from 0 to 4 points. Conclusions: There are systematic deviations from the RMP. Jaffe-based assays gave higher results, whereas the enzymatic-based assays gave lower results compared to the results of the RMP. The comparability of results is limited and could be disadvantageous to patients listed for liver transplantation.