[Comparison and agreement of the Cockcroft-Gault and MDRD equations to estimate glomerular filtration rate in diagnosis of occult chronic kidney disease].

INTRODUCTION AND OBJECTIVES: The estimation of Glomerular Filtration Rate (GFR) by Cockroft-Gault or simplified MDRD functions is a powerful tool for the Chronic Kidney Disease (CKD) diagnosis. The aims of the present study are: 1)-To analyze the accuracy between Cockcroft-Gault and simplified MDRD equations in the Hidden Renal Failure (HRF) diagnosis; and 2)-To know the profile and coronary risk of patients diagnosed of HRF for each equation.

PATIENTS AND METHODS: Ten year follow-up of a cross sectional study. A total of 845 patients between 35 and 74 years old (average age 55 years, 56.7% female) without evidence of cardiovascular disease and taken care in a urban primary health center. HRF was defined as an estimated GFR <60 ml/min/1.73 m2 in patients with normal values of creatinine (<1.3 mg/dl in women and <1.4 mg/dl in men )

RESULTS: 8.3% of studied population had HRF by Cockroft-Gault formula and 11.6% using MDRD. The HRF patients diagnosticated with Cockroft-Gault function were older (67.4 vs 64.4 years, p<0.001) and had a higher coronary risk using either the original Framingham equation and REGICOR function. Furthermore, those HRF patients diagnosticated using MDRD function had a higher body mass index (29.6 vs 26.3 kg/m2, p<0.001) and were women in a greater percentage. Kappa index of agreement of these two equations for diagnosis of HRF was 0,55. The HRF patients diagnosticated exclusively by the use of Cockroft-Gault function were mainly men (75%), older (69.1 vs 61.9 years, p<0.001) and they had a high coronary risk in the Framingham equation (32.7%) and REGICOR function (13.1%)

CONCLUSIONS: Cockroft-Gault and MDRD equations present a moderate agreement in HRF diagnosis (stage 3 of CKD) in patients between 35 and 74 years old. If we only use the MDRD function, a group of HRF patients would be excluded. This population was mainly male (75%), older (69 years old), with a high coronary risk estimated by original Framingham and REGICOR equations, and confirmed in the ten years follow-up of these patients.