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. 2024 Aug 20;17(11):sfae253.
doi: 10.1093/ckj/sfae253. eCollection 2024 Nov.

Immunosuppression and transplantation-related characteristics affect the difference between eGFR equations based on creatinine compared to cystatin C in kidney transplant recipients

Lukas Weidmann  1 , Catherine Laux  1 , Kai Castrezana Lopez  1 , Dusan Harmacek  1 , Britta George  1 , Seraina von Moos  1   2 , Thomas Schachtner  1
Affiliations

Immunosuppression and transplantation-related characteristics affect the difference between eGFR equations based on creatinine compared to cystatin C in kidney transplant recipients

Lukas Weidmann et al. Clin Kidney J. .

Abstract

Introduction: Previous studies show heterogeneity when applying estimated glomerular filtration (eGFR) equations to kidney transplant recipients (KTRs). However, research on the impact of transplantation-related characteristics on eGFR equations using creatinine (eGFRcr) compared to cystatin C (eGFRcys) is scarce.

Methods: We conducted a comprehensive analysis with three eGFRcr equations (Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2009, European Kidney Function Consortium (EKFC) 2021, kidney recipient specific-glomerular filtration rate KRS-GFR) 2023), comparing them to two eGFRcys (CKD-EPI 2012 and EKFC 2023) in 596 KTRs. Bland-Altman plots demonstrated relative differences according to different eGFR-stages. Multivariable logistic regression identified transplantation-related characteristics independently associated with smaller or greater differences between eGFRcr and eGFRcys equations.

Results: 94.3% of the cohort were White individuals. Median eGFR differed as much as 9 ml/min/1.73 m2 between equations. The median relative differences (Q2) were greater (more negative) when comparing the eGFRcr equations to eGFRcys CKD-EPI 2012, than when comparing them to eGFRcys EKFC 2023 (P < .001). Better average eGFR was associated with smaller mean relative differences in all comparisons but eGFRcr CKD-EPI 2009 with eGFR EKFC 2023 and eGFRcr EKFC 2021 with eGFRcys EKFC 2023. Living kidney donation and belatacept use were independent factors associated with a smaller difference (≥Q3) between eGFRcr and eGFRcys equations, while prednisone use or higher HbA1c were independently associated with a greater difference (≤Q1) between equations.

Conclusion: Different eGFR-stages, donor, or recipient characteristics, along with immunosuppression such as belatacept or prednisone, contribute to differences between eGFRcr and eGFRcys. These effects need to be considered in the clinical management of KTRs.

Keywords: creatinine; cystatin C; estimated glomerular filtration rate; immunosuppression; kidney transplantation.

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Conflict of interest statement

All authors had no competing interests to declare.

Figures

Graphical Abstract
Graphical Abstract
Figure 1:
Figure 1:
Study flowchart demonstrating the deduction of the study cohort. Exclusion criteria are listed. Abbreviation: TPL, transplantation.
Figure 2:
Figure 2:
Median eGFR values according to different eGFR equations. eGFR values of all individuals (n = 596) based on the different equations assessed in the study. The values are demonstrated as median (with IQR) in boxplots.
Figure 3:
Figure 3:
Median relative differences of all eGFRcr equations compared to the references. Visualization of the median relative differences (with IQR) in all individuals (n = 596) comparing each eGFRcr equation with the two reference equations (eGFRcys CKD-EPI 2012 and EKFC 2023) as forest plots. For all values, please see Appendix 3.
Figure 4:
Figure 4:
Bland–Altman plots of all eGFRcr equations compared to the references. Relative differences of all individuals (n = 596) plotted against the average eGFR between the examined equations. The red line demonstrates a Deming regression of the relative differences, according to different eGFR stages after standardization. The dotted lines visualize the 95% limits of agreement according to the Bland–Altman method. (A) Comparisons between eGFRcr equations and eGFRcys CKD-EPI 2012. (B) Comparisons between eGFRcr equations and eGFRcys EKFC 2023. For the linear functions of all Deming regressions, please see Appendix 4.
Figure 5:
Figure 5:
Associations of interest for smaller or greater differences between eGFRcr equations and references. Associations are demonstrated as forest plots with odds ratios (OR) and 95% CI (low and high). (A) Comparisons between eGFRcr equations and eGFRcys CKD-EPI 2012. (B) Comparisons between eGFRcr equations and eGFRcys EKFC 2023. *P between .05 and .1 (trend, but non-significant). For DKD the reciprocal values (OR, 95% CI) for LKD were calculated. For the exact values, please refer to Table 3. Abbreviations: Bela, belatacept; LKD, living kidney donation; PDN, prednisone; Age, age of the recipient; DKD, deceased kidney donation.
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