[Comparison of equations to estimate the glomerular filtration in people aged 75 or older without known renal disease]. / Comparación del uso de las ecuaciones de estimación del filtrado glomerular renal en personas de 75 años o más sin enfermedad renal conocida.

ABSTRACT

BACKGROUND AND OBJECTIVE: To compare the glomerular filtration rate (GFR) of patients aged 75 and older without known renal disease estimated by the MDRD-4-IDMS (MDRD) formula, urine 24h creatinine clearance (24h-CC) and Cockroft-Gault (CG) formula. PATIENTS AND METHODS: There were included 70 persons aged 75 and older from the geriatric external consultation. We compared the MDRD against the CG and the 24h-CC. RESULTS: Means of GFR were 24h-CC 56,60 + or - 22,79 ml/min/1.73 m(2) and CG 54,27 + or - 15,25 ml/min/1.73 m(2), significantly lower than with MDRD 69,78 + or - 18,53 ml/min/1.73 m(2) (p<0.001). Age was correlated with the difference between CG and MDRD (coefficient of correlation 0,59; r(2)0,34; p<0,001). Moderate agreement was obtained between MDRD with CG (k coefficient = 0.37; CI95%=0.19-0.55) and MDRD with 24-CC (k coefficient = 0.39; CI95% = 0.22-0.57). CONCLUSIONS: The MDRD and CG formulas to estimate the FGR in people aged 75 and older are not interchangeable. There are needed specific studies in old people to establish the most precise formula.