CST3 and chronic kidney disease: However, when comparing eGFRcr CKD-EPI 2009 with eGFRcys EKFC (Fig. 4b), or eGFRcr EKFC 2021 with eGFRcys EKFC (Fig. 4b), the Deming regression lines have a negative slope, suggesting a greater (and negative) mean relative difference with higher average eGFR, and therefore less favorable estimation of GFR according to cystatin C (also see Appendix 4).