Performance of creatinine-based GFR estimating equations in solid-organ transplant recipients

Abstract

Background: Accurate assessment of kidney function is important for the management of solid-organ transplant recipients. In other clinical populations, glomerular filtration rate (GFR) most commonly is estimated using the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) creatinine or the 4-variable MDRD (Modification of Diet in Renal Disease) Study equation. The accuracy of these equations compared with other GFR estimating equations in transplant recipients has not been carefully studied.

Study design: Diagnostic test study.

Setting & participants: Solid-organ transplant recipients longer than 6 months posttransplantation from 5 clinical populations (N=3,622, including recipients of kidney [53%], liver [35%], and other or multiple organs [12%]).

Index test: Estimated GFR (eGFR) using creatinine-based GFR estimating equations identified from a systematic review of the literature. Performance of the CKD-EPI creatinine and the MDRD Study equations was compared with alternative equations.

Reference test: Measured GFR (mGFR) from urinary clearance of iothalamate or plasma clearance of iohexol.

Measurements: Error (difference between mGFR and eGFR) expressed as P30 (proportion of absolute percent error <30%) and mean absolute error.

Results: We identified 26 GFR estimating equations. Mean mGFR was 55.1±22.7 (SD) mL/min/1.73 m(2). P30 and mean absolute error for the CKD-EPI and the MDRD Study equations were 78.9% (99.6% CI, 76.9%-80.8%) for both and 10.6 (99.6% CI, 10.1-11.1) versus 11.0 (99.6% CI, 10.5-11.5) mL/min/1.73 m(2), respectively; these equations were more accurate than any of the alternative equations (P <0.001 for all pairwise comparisons for both measures). They performed better than or as well as the alternative equations in most subgroups defined by demographic and clinical characteristics, including type of transplanted organ.

Limitations: Study population included few nonwhites and people with solid-organ transplants other than liver and kidneys.

Conclusions: The CKD-EPI creatinine and the MDRD Study equations perform better than the alternative creatinine-based estimating equations in solid-organ transplant recipients. They can be used for clinical management.

Keywords: Glomerular filtration rate (GFR) estimation; creatinine-based estimated glomerular filtration rate (eGFR) equation; kidney transplantation; renal function; solid-organ transplant recipient.