KDIGO 2012 Clinical Practice Guideline CKD classification rules out creatinine clearance 24 hour urine collection?

• Clearance of creatinine computed from 24-hour urine collection
• KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease
• Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations

ObjectivesThe 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 24 h urine collection) and e-GFR calculated with CKD-EPI or MDRD formulas.Design and methodsIn this retrospective study we analyze consecutive laboratory data: creatinine clearance 24 h 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 24 h 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.ResultsComparison 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 65/110 years aged group the concordance Kappas were 0.84, 0.38, and 0.36 respectively.ConclusionsThe 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 5 ml/min/1.73 m2/year.