How to Manage Kidney Transplant Recipients: Deciding Between Glomerular Filtration Rate-Estimating Equations,...

Management of renal transplant recipients involves measuring glomerular filtration rate and albuminuria; however, data are conflicting on the use of estimating equations or creatinine clearance and albumin-creatinine ratio in early morning urine or albumin excretion in 24-hour urine. We aimed to determine the performance of creatinine clearance and 3 estimated creatinine-based formulas and compare the usefulness of albumin-creatinine ratio related to albumin excretion in kidney transplant patients.

This cross-sectional study examined 300 consecutive kidney transplant patients. Serum creatinine was measured with Cobas-8000 and albumin-creatinine ratio, and albumin excretion was measured with Cobas-C311 (Roche Diagnostics, Hitachi, Tokyo, Japan). We quantified bias and percent bias, Bland-Altman results, and concordances in the classification of chronic kidney disease between formulas and creatinine clearance. We also conducted linear regression analyses of all parameters and for cutoffs of 30 and 300 mg/24 hours and determined the ability of albumin-creatinine ratio to predict abnormal albumin excretion (receiver operator characteristic curve analysis).

Bias (mL/min/1.73 m2), percent bias, and concordances between creatinine clearance and Cockcroft-Gault, Modification of Diet in Renal Disease, and Chronic Kidney Disease Epidemiology Colla-boration formulas in the classification of chronic kidney disease were as follows: 15.89, 20.91%, and 0.35; 20.52, 27.89%, and 0.21; and 18.24, 25.39%, and 0.27, respectively. Regression analyses showed a weak but significantly linear relationship for the cutoff values (P < .001). Receiver operator characteristic curve analyses showed areas under the curve of 0.957 and 0.997 at cutoffs of 30 and 300 mg/24 hours. In our patients, the cutoffs were 27 mg/g (88.38% sensitivity, 92.16% specificity) and 238 mg/g (80.00% sensitivity, 97.45% specificity).

We suggest using estimating equations and albumin-creatinine ratio with caution. In routine management of patients with successive stable revisions, we recommended using the Cockcroft-Gault or Chronic Kidney Disease Epidemiology Collaboration formulas and albumin-creatinine ratio.