Cystatin C, Glomerular filtration, Estimated glomerular filtration rate, Post-analytical phase, External Quality Assessment

Objectives: Kidney Disease Improving Global Outcomes (KDIGO) guidelines recommend reporting the cystatin C concentration result together with estimated glomerular filtration rate (eGFRcys). The extent to which the recommendation is implemented to practice is not known. The aim of this study is to determine the implementation extent and to show howlaboratories that have not yet implemented the measure can be guided to adopting it to their routines. Design: Cross - sectional study.Settings: SEKK, spol. s.r.o., Za Pasáží 1609, 530 02 Pardubice. Material and methods: Evaluation of cystatin C post-analytical phase was performed by an online electronic questionnaire which was added to routine cystatin C External Quality Assessment (EQA) scheme. A total of 70 participants (59 from theCzech Republic and 11 from Slovakia) were given the questionnaire. They reported traceability of their method calibration to international standard ERM DA471/IFCC, and equations for eGFRcys. Answers were analysed. Results: In the end, 63 participants responded to the questionnaire. Traceability of calibration to ERM DA471/IFCC was declared by 53 responders. A total of 53 laboratories stated reporting eGFR in all adult patients and 4 participants stated reporting eGFR only on direct request. Six laboratories did not report eGFR. The Chronic Kidney Disease Epidemiology Collaboration (CKD - EPI) equation was used by 57 laboratories. Of them, 22 laboratories also used combined equation with creatinine and three laboratories also calculated Caucasian, Asian, Pediatric and Adult (CAPA) equation. Conclusion: Majority of laboratories follow the KDIGO guidelines. Further education on calibration traceability and eGFRaccompanying all cystatin C concentration results is still needed.