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Updated: Jul 4, 2025
Physiology Lab Demonstration: Glomerular Filtration Rate in a Rat
Published on: July 26, 2015
Different methods for assessing glomerular filtration rate in the elderly
Gilsirene Scantelbury de Almeida1, Noeli das Neves Toledo1, Miharu Maguinoria Matsuura Matos2
1Universidade Federal do Amazonas, Manaus School of Nursing - Manaus (AM), Brazil.
Insights
The Collaboration Epidemiology of Chronic Kidney Disease (CKD-EPI) equation using creatinine is the best method for estimating glomerular filtration in the elderly. Creatinine clearance showed the poorest performance, indicating 24-hour urine collection is unnecessary.
Area of Science:
- Nephrology
- Geriatrics
- Clinical Chemistry
Background:
- Estimating glomerular filtration rate (eGFR) is crucial for managing chronic kidney disease (CKD).
- Cystatin C is a reliable marker for eGFR, but its cost can be a limitation.
- Alternative methods using creatinine are needed for cost-effective eGFR assessment in the elderly.
Purpose of the Study:
- To identify the optimal creatinine-based equation for estimating glomerular filtration rate (eGFR) in elderly individuals.
- To compare the performance of various creatinine-based eGFR equations against cystatin C-based eGFR.
Main Methods:
- A cohort of 166 elderly individuals (≥60 years) was studied.
- Blood samples were analyzed for creatinine and cystatin C.
- eGFR was calculated using Creatinine Clearance, Cockcroft-Gault, MDRD, and CKD-EPI creatinine equations, with CKD-EPI cystatin C as the reference.
- Statistical analysis included linear regression, Bland-Altman plots, and ROC curves.
Main Results:
- The CKD-EPI creatinine equation demonstrated the highest correlation with the reference method.
- Creatinine clearance exhibited the lowest performance.
- Bland-Altman and ROC analyses corroborated the superiority of the CKD-EPI creatinine equation.
Conclusions:
- The CKD-EPI creatinine equation is the preferred method for eGFR estimation in the elderly population.
- The poor performance of creatinine clearance suggests 24-hour urine collection is not required for eGFR assessment in this demographic.
- This finding supports the use of simpler, blood-based markers for routine eGFR monitoring in older adults.
Objective:
The objective of this study was to identify the best method to replace cystatin C in the evaluation of glomerular filtration in the elderly.
Methods:
Individuals over 60 years of age from a primary care center were studied. Blood was collected to determine creatinine and cystatin C and 24-h urine. Three methods were compared to determine glomerular filtration: Creatinine clearance, Cocroft-Gault, modification of diet in renal disease, and Collaboration Epidemiology of Chronic Kidney Disease based on creatinine, considering as a reference the determination of glomerular filtration using the cystatin-based Chronic Kidney Disease Epidemiology Collaboration equation. The statistical methods used were linear regression, Bland-Altman curve, and receiver operating characteristic.
Results:
A total of 180 elderly people were evaluated, but 14 patients were lost from the sample, resulting in a total of 166 patients. The average age of patients was 66.9±6.1 years, and 69.8% were females. Regarding the number of patients eligible for the study, there were 12 black, 108 brown, and 46 white, 42.77% hypertensive, and 38.3% diabetic. Glomerular filtration was less than 60 mL/min in 22.28% of patients. Regarding the evaluation of the different equations, the correlation coefficient was lower for creatinine clearance and progressively higher for Cocroft-Gault, modification of diet in renal disease, and Collaboration Epidemiology of Chronic Kidney Disease based on creatinine. The Bland-Altman diagram and the receiver operating characteristic curve showed similar performance to the correlation coefficient for the different equations evaluated.
Conclusion:
Collaboration Epidemiology of Chronic Kidney Disease based on creatinine presented the best performance. Creatinine debug had the worst performance, which reinforces the idea that 24-h urine collection is unnecessary in these patients.
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