Correlation and concordance between the primary glomerular filtration MDRD-6 and creatinine clearance by the conventional method

Background: The aim of the study was to determine the correlation and concordance between the primary glomerular filtration rate estimated by the MDRD-6 (Modification of Diet in Renal Disease, (mL/min/1.73 m2) equation and the creatinine clearance in 24-hour urine (DCr.mL/min) by conventional method.

Methods: Retrospective, observational and comparative study. We studied 180 patients, were quantified in serum: creatinine (Cr), urea nitrogen (BUN) albumin (Alb) and, in urine for 24 hours: creatinine (Cr). The calculation of the primary glomerular filtration was made with the equation MDRD-6 (mL/min/1.73 m2) and for the creatinine clearance in urine and 24 hours the equation of the conventional method (mL/min). The comparison of methods was calculated with the correlation coefficient of Person and the agreement with the unweighted Kappa test using the Landis and Koch classification.

Results: The correlation obtained between both methods was r2 = 0.4238 with a value p = < 0.0001, the strength of agreement between both Kappa methods = 0.1631.

Conclusions: The primary glomerular filtration estimated by the MDRD-6 equation (mL/min/1.73 m2) and the creatinine clearance in urine of 24 hours estimated by the conventional method equation (mL/min) have a poor correlation and poor agreement.