What Is the Correct Approach for Comparing GFR by Different Methods across Levels of GFR?

Rule, Andrew D.; Kremers, Walter K.

doi:10.2215/cjn.07530716

Cited by 15 publications

(12 citation statements)

References 11 publications

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“…The presentation was limited to eGFR in the range of 20-90 mL/min/1.73 m 2 since generally <5% of the patients had mGFR or eGFR outside this range. The constancy of bias stratified by eGFR in the accuracy diagrams is an indicator of how similar an equation behaves in a validation cohort compared with the original development cohort [14,23].…”

Section: Statistical Analysesmentioning

confidence: 99%

Comparison of glomerular filtration rate estimating equations derived from creatinine and cystatin C: validation in the Age, Gene/Environment Susceptibility-Reykjavik elderly cohort

Björk

Grubb

Gudnason

et al. 2017

Nephrology Dialysis Transplantation

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Background. Validation studies comparing glomerular filtration rate (GFR) equations based on standardized creatinine and cystatin C assays in the elderly are needed. The Icelandic Age, Gene/Environment Susceptibility-Kidney cohort was used to compare two pairs of recently developed GFR equations, the revised Lund-Malmö creatinine equation (LMR Cr) and the arithmetic mean of the LMR Cr and Caucasian, Asian, Paediatric and Adult cystatin C equations (MEAN LMRþCAPA), as well as the Full Age Spectrum creatinine equation (FAS Cr) and its combination with cystatin C (FAS CrþCys), with the corresponding pair of Chronic Kidney Disease Epidemiology Collaboration equations (CKD-EPI Cr and CKD-EPI CrþCys). Methods. A total of 805 individuals, 74-93 years of age, underwent measurement of GFR (mGFR) using plasma clearance of iohexol. Four metrics were used to compare the performance of the GFR equations: bias, precision, accuracy [including the percentage of participants with estimated GFR (eGFR) within 30% of mGFR (P 30)] and the ability to detect mGFR <60 mL/min/1.73 m 2. Results. All equations had a P 30 >90%. LMR Cr and FAS Cr yielded significantly higher precision and P 30 than CKD-EPI Cr , while bias was significantly worse. LMR Cr , FAS Cr and CKD-EPI Cr showed similar ability to detect mGFR <60 mL/min/1.73 m 2 based on the area under the receiver operating characteristic curves. MEAN LMRþCAPA , FAS CrþCys and CKD-EPI CrþCys all exhibited consistent improvements compared with the corresponding creatinine-based equations. Conclusion. None of the creatinine-based equations was clearly superior overall in this community-dwelling elderly cohort. The addition of cystatin C improved all of the creatinine-based equations.

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Section: Statistical Analysesmentioning

confidence: 99%

Comparison of glomerular filtration rate estimating equations derived from creatinine and cystatin C: validation in the Age, Gene/Environment Susceptibility-Reykjavik elderly cohort

Björk

Grubb

Gudnason

et al. 2017

Nephrology Dialysis Transplantation

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“…Second, we recently questioned whether the observed larger ratio of CrCl to measured GFR among those with lower GFR is actually due to proportionally greater tubular creatinine secretion with chronic kidney disease (CKD) progression, as is commonly believed, or whether this can be entirely accounted for by (random) measurement error [3,10]. But our prior study was limited since it was based on only cross-sectional analysis of enrollees from one CKD study (Chronic Renal Insufficiency Cohort [CRIC]), and the CrCl and measured GFR were not obtained simultaneously [3].…”

Section: Introductionmentioning

confidence: 99%

Tubular secretion of creatinine and kidney function: an observational study

et al. 2020

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Background: Prior papers have been inconsistent regarding how much creatinine clearance (CrCl) overestimates glomerular filtration rate (GFR). A recent cross-sectional study suggested that measurement error alone could entirely account for the longstanding observation that CrCl/GFR ratio is larger when GFR is lower among patients with chronic kidney disease (CKD); but there have been no validation of this in other cohorts. Methods: To fill these gaps in knowledge regarding the relation between CrCl and GFR, we conducted crosssectional and longitudinal analysis of the Modification of Diet in Renal Disease study (MDRD) and African American Study of Kidney Disease and Hypertension (AASK); and cross-sectional analysis of a clinical dataset from the Mayo Clinic of four different patient populations (CKD patients, kidney transplant recipients, post kidney donation subgroup and potential kidney donors). In the cross-sectional analyses (MDRD, AASK and Mayo Clinic cohort), we examined the relation between the CrCl/iothalamate GFR (iGFR) ratio at different categories of iGFR or different levels of CrCl. In the MDRD and AASK longitudinal analyses, we studied how the CrCl/iGFR ratio changed with those who had improvement in iGFR (CrCl) over time versus those who had worsening of iGFR (CrCl) over time. Results: Observed CrCl/iGFR ratios were generally on the lower end of the range reported in the literature for CKD (median 1.24 in MDRD, 1.13 in AASK and 1.25 in Mayo Clinic cohort). Among CKD patients in whom CrCl and iGFR were measured using different timed urine collections, CrCl/iGFR ratio were higher with lower iGFR categories but lower with lower CrCl categories. However, among CKD patients in whom CrCl and iGFR were measured using the same timed urine collections (which reduces dis-concordant measurement error), CrCl/iGFR ratio were higher with both lower iGFR categories and lower CrCl categories. Conclusions: These data refute the recent suggestion that measurement error alone could entirely account for the longstanding observation that CrCl/GFR ratio increases as GFR decreases in CKD patients. They also highlight the lack of certainty in our knowledge with regard to how much CrCl actually overestimates GFR.

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“…The CKD-EPI consortium meta-analysis showed little difference between estimating equations based on creatinine, cystatin C or both in terms of bias, but significant improvements in both precision and accuracy were reported for equations based on cystatin C compared to equations based on creatinine alone [5]. However, the CKD-EPI equation based on cystatin C may not perform as well in other populations [22], and differences in population characteristics of our study population to those included in the CKD-EPI consortium analysis may explain these disparate results.…”

Section: Discussionmentioning

confidence: 99%

Comparison of creatinine and cystatin C based eGFR in the estimation of glomerular filtration rate in Indigenous Australians: The eGFR Study

Barr

Maple-Brown

Barzi

et al. 2017

Clinical Biochemistry

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Background: The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation that combines creatinine and cystatin C is superior to equations that include either measure alone in estimating glomerular filtration rate (GFR). However, whether cystatin C can provide any additional benefits in estimating GFR for Indigenous Australians, a population at high risk of end-stage kidney disease (ESKD) is unknown.

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What Is the Correct Approach for Comparing GFR by Different Methods across Levels of GFR?

Cited by 15 publications

References 11 publications

Comparison of glomerular filtration rate estimating equations derived from creatinine and cystatin C: validation in the Age, Gene/Environment Susceptibility-Reykjavik elderly cohort

Comparison of glomerular filtration rate estimating equations derived from creatinine and cystatin C: validation in the Age, Gene/Environment Susceptibility-Reykjavik elderly cohort

Tubular secretion of creatinine and kidney function: an observational study

Comparison of creatinine and cystatin C based eGFR in the estimation of glomerular filtration rate in Indigenous Australians: The eGFR Study

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