Background: The incidence of chronic kidney disease (CKD) is relatively high in Guyana. eGFR (estimated glomerular filtration rate) reporting allows for early-stage CKD identification, when therapeutic interventions can prevent CKD progression. Accurate creatinine measurements are essential for valid eGFR calculations. This study was undertaken to assess the accuracy of creatinine measurements in Guyana prior to implementing routine eGFR reporting.
Methods: Sixteen Guyanese laboratories participated in this study. Each laboratory received a common set of blinded human serum samples (n=3) containing clinically relevant creatinine concentrations, assigned by an international reference method (ID-GCMS). Laboratories performed repeated measurements of creatinine in each sample. These data were used to calculate bias, precision and total error (TE) for each creatinine method.
Linear regression was used to compare measured creatinine results to assigned reference sample values and to post-analytically correct calibration bias, a priori, for recent patient results from each laboratory. Patient eGFR profiles were compared before and after bias correction.
Results: The mean across samples CV and bias for all labs were 9% (range 2.5-39.3%) and 11% positive (range 0.4-29.1%), respectively. The mean total error (TE) was 28.6%. If the mean TE from a subset of the better performing laboratories (CV <7%) were to apply nationally, an “all stage” eGFR misclassification rate of 36% would result.
Conclusions: There is a pressing need to improve the accuracy of creatinine measurements in Guyana as, at this time, routine reporting of eGFR by Guyanese laboratories cannot be recommended based on the accuracy data presented in this study.
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