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Reliability of the MDRD method for estimating glomerular filtration rate in relation to gender, body mass index and extracellular fluid volume
Author(s) -
Bird N. J.,
Peters C.,
Michell A. R.,
Peters A. M.
Publication year - 2008
Publication title -
european journal of clinical investigation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.164
H-Index - 107
eISSN - 1365-2362
pISSN - 0014-2972
DOI - 10.1111/j.1365-2362.2008.01960.x
Subject(s) - iohexol , renal function , gold standard (test) , urology , medicine , extracellular fluid , creatinine , body mass index , body surface area , chemistry , extracellular , biochemistry
Background The accuracy of estimating glomerular filtration rate from plasma creatinine (eGFR) has been questioned but it is unclear how much covert error in several reference methods that have been used has contributed to this perceived inaccuracy. The aim of the study was to evaluate eGFR in comparison with a second ‘gold standard’ to test the performance of the primary gold standard and to examine the influence of patient demographics (age, body mass index (BMI), extracellular fluid volume (ECV) and gender). Design Non‐fasting multisample GFR and ECV were measured in 80 subjects simultaneously and independently with Cr‐51‐EDTA (GFR EDTA ) and iohexol (GFR iohexol ). Percentage bias and imprecision in the prediction of, and disagreement with, GFR EDTA were compared between eGFR and GFR iohexol . Another simplified method for measuring GFR, the slope‐only method ( SO GFR), was also evaluated against multisample GFR (measured with the opposing indicator). Accuracies were assessed in all subjects and across age, BMI and ECV boundaries of 65 y, 29 kg m −2 and 14 L. Results eGFR was less precise than GFR iohexol (imprecisions of 22·3% and 12·9%; P < 0·01). The precision of SO GFR was intermediate between eGFR and GFR iohexol . Both GFR iohexol and eGFR were less precise in the elderly, the obese and men, but minimally influenced by ECV. SO GFR was minimally influenced by subject demographics. Conclusion Although eGFR does not predict GFR (based on a primary gold standard) as accurately as a second gold standard, a significant component of its poor performance is the result of inaccuracy in the primary gold standard. SO GFR measured with Cr‐51‐EDTA is superior to eGFR.