title: Creatinine-Based and Cystatin C-Based GFR Estimating Equations and Their Non-GFR Determinants in Kidney Transplant Recipients.
abstract: eGFR equations have been evaluated in kidney transplant recipients with variable performance. We assessed the performance of the Modification of Diet in Renal Disease equation and the Chronic Kidney Disease Epidemiology Collaboration equations on the basis of creatinine, cystatin C, and both (eGFR creatinine-cystatin C) compared with measured GFR by iothalamate clearance and evaluated their non-GFR determinants and associations across 15 cardiovascular risk factors.
  
  
  
  A cross-sectional cohort of 1139 kidney transplant recipients >1 year after transplant was analyzed. eGFR bias, precision, and accuracy (percentage of estimates within 30% of measured GFR) were assessed. Interaction of each cardiovascular risk factor with eGFR relative to measured GFR was determined.
  
  
  
  Median measured GFR was 55.0 ml/min per 1.73 m(2). eGFR creatinine overestimated measured GFR by 3.1% (percentage of estimates within 30% of measured GFR of 80.4%), and eGFR Modification of Diet in Renal Disease underestimated measured GFR by 2.2% (percentage of estimates within 30% of measured GFR of 80.4%). eGFR cystatin C underestimated measured GFR by -13.7% (percentage of estimates within 30% of measured GFR of 77.1%), and eGFR creatinine-cystatin C underestimated measured GFR by -8.1% (percentage of estimates within 30% of measured GFR of 86.5%). Lower measured GFR associated with older age, women, obesity, longer time after transplant, lower HDL, lower hemoglobin, lower albumin, higher triglycerides, higher proteinuria, and an elevated cardiac troponin T level but did not associate with diabetes, smoking, cardiovascular events, pretransplant dialysis, or hemoglobin A1c. These risk factor associations differed for five risk factors with eGFR creatinine, six risk factors for eGFR Modification of Diet in Renal Disease, ten risk factors for eGFR cystatin C, and four risk factors for eGFR creatinine-cystatin C.
  
  
  
  Thus, eGFR creatinine and eGFR creatinine-cystatin C are preferred over eGFR cystatin C in kidney transplant recipients because they are less biased, more accurate, and more consistently reflect the same risk factor associations seen with measured GFR.
authors.affiliation: Division of Nephrology and Hypertension, Mayo Clinic, Phoenix, Arizona; and.
authors.forename: Mira T
authors.initials: MT
authors.lastname: Keddis
authors.affiliation: Division of Nephrology and Hypertension.
authors.forename: Hatem
authors.initials: H
authors.lastname: Amer
authors.affiliation: Renal Laboratory, Department of Laboratory Medicine and Pathology, and.
authors.forename: Nikolay
authors.initials: N
authors.lastname: Voskoboev
authors.affiliation: Department of Health Sciences Research Laboratory, Mayo Clinic, Rochester, Minnesota.
authors.forename: Walter K
authors.initials: WK
authors.lastname: Kremers
authors.affiliation: Division of Nephrology and Hypertension.|Department of Health Sciences Research Laboratory, Mayo Clinic, Rochester, Minnesota.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Rule
authors.affiliation: Division of Nephrology and Hypertension.|Renal Laboratory, Department of Laboratory Medicine and Pathology, and.
authors.forename: John C
authors.initials: JC
authors.lastname: Lieske
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media; D003404:Creatinine / Q000097:blood*; D003430:Cross-Sectional Studies; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D000074024:Immunoturbidimetry; D007483:Iothalamic Acid; D007668:Kidney / Q000502:physiology*; D016030:Kidney Transplantation; D008297:Male; D055641:Mathematical Concepts; D008875:Middle Aged; D012307:Risk Factors
chemical_list: D003287:Contrast Media; D055316:Cystatin C; D007483:Iothalamic Acid; D003404:Creatinine
keywords: Cardiovascular Diseases; Creatinine; Cystatin C; Iothalamic Acid; Smoking; Triglycerides; diabetes mellitus; glomerular filtration rate; kidney transplantation; obesity; proteinuria; risk factors