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Performance of Creatinine and Cystatin C-Based Equations to Estimate Glomerular Filtration Rate Among Patients With
John Roth1, John C Lieske2, Sandra M Herrmann2
1Department of Internal Medicine (J.R.), Mayo Clinic, Rochester, MN.
Insights
Estimated glomerular filtration rate (eGFR) equations using creatinine perform poorly in heart failure (HF) patients. Cystatin C-based eGFRs offer better accuracy, especially in HF with reduced ejection fraction (HFrEF).
Area of Science:
- Nephrology
- Cardiology
- Clinical Chemistry
Background:
- Estimated glomerular filtration rate (eGFR) performance may be compromised in heart failure (HF) patients due to confounding factors.
- Limited research exists on eGFR accuracy in HF, particularly stratified by ejection fraction type.
- This study assesses current creatinine and cystatin C-based eGFR equations against measured GFR (mGFR) in HF patients.
Purpose of the Study:
- To evaluate the performance of creatinine-based eGFR (eGFRcr), cystatin C-based eGFR, and combined eGFR equations compared to mGFR in patients with HF.
- To stratify performance analysis based on HF type: HF with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF).
Main Methods:
- Retrospective analysis of Mayo Clinic patients with mGFR, serum creatinine, cystatin C, and echocardiogram data.
- HF classification based on ICD codes and ejection fraction (EF ≥50% for HFpEF, <50% for HFrEF).
- Comparison of CKD-EPI eGFRcr, eGFR cystatin C, and combined eGFR equations for bias and accuracy (1-P30) against mGFR.
Main Results:
- HF patients exhibited higher creatinine and cystatin C levels than controls.
- eGFRcr showed greater overestimation of mGFR in both HF groups compared to controls.
- Cystatin C-based equations demonstrated superior accuracy in HF groups, especially in HFrEF (1-P30 of 28-34%) versus eGFRcr (60%).
Conclusions:
- Creatinine-based eGFR exhibits inferior performance with more bias and less accuracy in HF patients.
- Cystatin C-based eGFR equations provide a more accurate assessment of kidney function in HF patients.
- The improved accuracy of cystatin C-based eGFR is particularly notable in patients with HFrEF.
Background:
The performance of estimated glomerular filtration rate (eGFR) among patients with heart failure (HF) may be worse than in the general population due to a higher prevalence of confounding factors affecting creatinine and cystatin C. Studies in this area are scarce and not stratified by type of HF. We evaluated the performance of current creatinine and cystatin C equations (eGFRcr, eGFRcys, and eGFRcrcys) compared with measured GFR (mGFR) among patients with HF stratified by ejection fraction.
Methods:
We pulled data on Mayo Clinic patients with an mGFR performed for clinical indications from 2011 to 2023, with serum creatinine and cystatin C measured within 7 days and an echocardiogram performed up to 1 year before the mGFR date. HF was identified by the presence of International Classification of Diseases codes within 1 year before the mGFR and subgrouped into ejection fraction (EF) ≥50% (HFEF≥50%, n=182) or <50% (HFEF<50%, n=115) and compared with no-HF controls (n=1871). CKD-EPI (and EKFC) eGFRcr, eGFRcys, and eGFRcrcys equations were calculated and compared for bias (mGFR minus eGFR) and accuracy (1-P30, proportion of people with ≥30% difference between eGFR and mGFR). CIs were generated by bootstrapping.
Results:
The HF groups were characterized by older age, higher proportion of males, more diabetes, higher creatinine, and higher cystatin C than controls. In terms of bias, eGFRcr overestimated mGFR to a greater extent in both HF groups compared with controls, whereas eGFRcys and eGFRcrcys showed similar bias in both HF groups and controls. In the HF groups, cystatin C-based equations were more accurate than eGFRcr, particularly within HFEF<50% (1-P30 of 28% and 34% for CKD-EPI eGFRcys and eGFRcrcys, respectively, versus 60% for eGFRcr), whereas eGFRcrcys was more accurate in controls. The CKD-EPI and EKFC equations were overall convergent, showing similar results.
Conclusions:
Among patients with HF, eGFRcr demonstrates inferior performance (more bias and less accuracy) compared with cystatin C-based eGFRs, with this effect being more pronounced in those with HFEF<50%.
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