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KDIGO 2012 Clinical Practice Guideline CKD classification rules out creatinine clearance 24 hour urine collection?
A Ognibene1, G Grandi1, M Lorubbio1
1Laboratorio Generale, Azienda Ospedaliero, Universitaria Careggi, Firenze, Italy.
Insights
Creatinine clearance (CrCl) measurements classify kidney function differently than estimated GFR (e-GFR) equations. CrCl is unreliable for detecting small, annual GFR declines in chronic kidney disease (CKD).
Area of Science:
- Nephrology
- Clinical Chemistry
- Biomarkers
Background:
- Current Chronic Kidney Disease (CKD) guidelines recommend using serum creatinine-based equations for Glomerular Filtration Rate (GFR) estimation.
- Despite guidelines, 24-hour urine collection for creatinine clearance (CrCl) remains a common practice in many clinical settings.
- Discrepancies in GFR assessment methods may impact CKD diagnosis and management.
Purpose of the Study:
- To compare the classification of kidney function using creatinine clearance (CrCl) versus estimated GFR (e-GFR) calculated with CKD-EPI and MDRD formulas.
- To evaluate the reliability of CrCl in identifying patients with CKD and declining GFR.
Main Methods:
- Retrospective analysis of laboratory data from 15,777 adult patients (2011-2013).
- Collected data included CrCl (24-hour urine), serum creatinine, age, and sex.
- Compared CrCl results with e-GFR calculated using CKD-EPI and MDRD equations.
Main Results:
- Bias between e-GFR (CKD-EPI/MDRD) and GFR by CrCl was substantial (11.34-11.4).
- Concordance between MDRD and CKD-EPI e-GFR was high (0.78-0.84).
- Concordance between e-GFR (MDRD/CKD-EPI) and CrCl was low (0.34-0.41), indicating significant classification differences.
Conclusions:
- Creatinine clearance (CrCl) yields different patient classifications compared to GFR estimation equations.
- CrCl is not a reliable method for detecting annual GFR decreases of 5 ml/min/1.73m²/year, crucial for CKD monitoring.
- Relying on CrCl may lead to misclassification and suboptimal management of chronic kidney disease.
Objectives:
The recent guideline for the evaluation and management of Chronic Kidney Disease recommends assessing GFR employing equations based on serum creatinine; despite this, creatinine clearance 24-hour urine collection is used routinely in many settings. In this study we compared the classification assessed from CrCl (creatinine clearance 24h urine collection) and e-GFR calculated with CKD-EPI or MDRD formulas.
Design And Methods:
In this retrospective study we analyze consecutive laboratory data: creatinine clearance 24h urine collection, serum creatinine and demographic data such as sex and age from 15,777 patients >18 years of age collected from 2011 to 2013 in our laboratory at Careggi Hospital. The results were then compared to the estimated GFR calculated with the equations according to the recent treatment guidelines. Consecutive and retrospective laboratory data (creatinine clearance 24h urine collection, serum creatinine and, demographic data such as sex and age) from 15,777 patients >18 years of age seen at Careggi Hospital were collected.
Results:
Comparison between e-GFR calculated with CKD-EPI or MDRD formulas and GFR according CrCl determinations and bias [95% CI] were 11.34 [-47,4/70.1] and 11.4 [-50.2/73] respectively. The concordance for 18/65 years aged group when compared with e-GFR classification between MDRD vs CKDEPI, MDRD vs CrCl and CKD-EPI vs CrCl were 0.78, 0.34, and 0.41 respectively, while in the 65/110years aged group the concordance Kappas were 0.84, 0.38, and 0.36 respectively.
Conclusions:
The use of CrCl provides a different classification than the estimation of GFR using a prediction equation. The CrCl is unreliable when it is necessary to identify CKD subjects with decrease of GFR of 5ml/min/1.73m(2)/year.
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