Comparison of glomerular filtration rate estimating equations derived from creatinine and cystatin C : Validation in the Age, Gene/Environment Susceptibility-Reykjavik elderly cohort

• Background. Validation studies comparing glomerular filtration rate (GFR) equations based on standardized creatinine and cystatin C assays in the elderly are needed. The Icelandic Age, Gene/Environment Susceptibility-Kidney cohort was used to compare two pairs of recently developed GFR equations, the revised Lund-Malmö creatinine equation (LMRCr) and the arithmetic mean of the LMRCr and Caucasian, Asian, Paediatric and Adult cystatin C equations (MEANLMRþCAPA), as well as the Full Age Spectrum creatinine equation (FASCr) and its combination with cystatin C (FASCrþCys), with the corresponding pair of Chronic Kidney Disease Epidemiology Collaboration equations (CKD-EPICr and CKD-EPICrþCys). Methods. A total of 805 individuals, 74-93 years of age, underwent measurement of GFR (mGFR) using plasma clearance of iohexol. Four metrics were used to compare the performance of the GFR equations: bias, precision, accuracy [including the percentage of participants with estimated GFR (eGFR) within 30% of mGFR (P30)] and the ability to detect mGFR <60 mL/min/1.73 m2. Results. All equations had a P30 >90%. LMRCr and FASCr yielded significantly higher precision and P30 than CKD-EPICr, while bias was significantly worse. LMRCr, FASCr and CKD-EPICr showed similar ability to detect mGFR <60 mL/min/1.73 m2 based on the area under the receiver operating characteristic curves. MEANLMRþCAPA, FASCrþCys and CKD-EPICrþCys all exhibited consistent improvements compared with the corresponding creatinine-based equations. Conclusion. None of the creatinine-based equations was clearly superior overall in this community-dwelling elderly cohort. The addition of cystatin C improved all of the creatinine-based equations.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Urologi och njurmedicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Urology and Nephrology (hsv//eng)

Nyckelord

Chronic kidney disease

Elderly

Glomerular filtration rate

Kidney function tests

Renal failure

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