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Updated: Jul 1, 2025
Physiology Lab Demonstration: Glomerular Filtration Rate in a Rat
Published on: July 26, 2015
The error of estimated GFR in predialysis care
Beatriz Escamilla-Cabrera1,2, Sergio Luis-Lima3,4, Eduardo Gallego-Valcarce5
1Nephrology Department, Complejo Hospitalario Universitario de Canarias, La Laguna, Spain.
Abstract:
The error of estimated glomerular filtration rate (eGFR) and its consequences in predialysis are unknown. In this prospective multicentre study, 315 predialysis patients underwent measured GFR (mGFR) by the clearance of iohexol and eGFR by 52 formulas. Agreement between eGFR and mGFR was evaluated by concordance correlation coefficient (CCC), total deviation index (TDI) and coverage probability (CP). In a sub-analysis we assessed the impact of eGFR error on decision-making as (i) initiating dialysis, (ii) preparation for renal replacement therapy (RRT) and (iii) continuing clinical follow-up. For this sub-analysis, patients who started RRT due to clinical indications (uremia, fluid overload, etc.) were excluded. eGFR had scarce precision and accuracy in reflecting mGFR (average CCC 0.6, TDI 70% and cp 22%) both in creatinine- and cystatin-based formulas. Variations -larger than 10 ml/min- between mGFR and eGFR were frequent. The error of formulas would have suggested (a) premature preparation for RTT in 14% of stable patients evaluated by mGFR; (b) to continue clinical follow-up in 59% of subjects with indication for RTT preparation due to low GFRm and (c) to delay dialysis in all asymptomatic patients (n = 6) in whom RRT was indicated based on very low mGFR. The error of formulas in predialysis was frequent and large and may have consequences in clinical care.
Insights
Estimated glomerular filtration rate (eGFR) formulas show significant errors in predialysis patients, impacting clinical decisions regarding dialysis initiation and renal replacement therapy preparation. These inaccuracies may affect patient care.
Area of Science:
- Nephrology
- Clinical Chemistry
- Medical Statistics
Background:
- The accuracy of estimated glomerular filtration rate (eGFR) in predialysis patients is not well understood.
- Clinical decisions regarding renal replacement therapy (RRT) depend on accurate GFR assessment.
- Previous studies have not fully evaluated the real-world impact of eGFR errors in predialysis care.
Purpose of the Study:
- To evaluate the accuracy and precision of 52 eGFR formulas compared to measured GFR (mGFR) in 315 predialysis patients.
- To assess the clinical consequences of eGFR errors on decisions related to dialysis initiation and RRT preparation.
- To quantify the impact of formula inaccuracies on patient management in a prospective, multicentre setting.
Main Methods:
- Prospective, multicentre study involving 315 predialysis patients.
- Measured GFR (mGFR) determined by iohexol clearance.
- Agreement between eGFR and mGFR assessed using concordance correlation coefficient (CCC), total deviation index (TDI), and coverage probability (CP).
Main Results:
- eGFR formulas demonstrated poor precision and accuracy (average CCC 0.6, TDI 70%, CP 22%) compared to mGFR.
- Frequent variations exceeding 10 ml/min between eGFR and mGFR were observed.
- eGFR errors led to potential misclassifications: 14% premature RRT preparation, 59% delayed RRT preparation, and delayed dialysis in asymptomatic patients needing RRT.
Conclusions:
- Current eGFR formulas exhibit significant errors in predialysis patients.
- These inaccuracies can lead to inappropriate clinical decisions regarding RRT initiation and management.
- The substantial error in eGFR formulas necessitates caution and potentially revised assessment methods in predialysis care.
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