Modification of diet in renal disease (MDRD) and Cockcroft-Gault equations in estimation of glomerular filtration rate in patients with coronary artery disease and hypertension

Abstract

Background Gromelural filtration rate (GFR) provides the most accurate estimation of renal function. Reliable GRF estimation is critical to diagnosis of chronic kidney disease. The aim of the study was to evaluate the Cockcroft-Gault (CG) and Modification of Diet in Renal Disease (MDRD) equations for their accuracy in determining GFR in hypertensive patients with coronary artery disease (CAD) and to assess a frequency and factors determining renal impairment in this group of patients.
Material and methods We recruited 299 consecutive patients (191 men and 108 women) admitted to hospital, aged 63.6 ± 11.3 years with 1-3 stage arterial hypertension acc. to ESH/ESC (duration 10.8 ± 8.7 years) and CAD (6.8 ± 3.2 years). Among them 89 (29.8%) pts had type 2 diabetes. There were 99 (33.1%) patients in I CCS class, 160 (53.5%) - in II, and 40 (13.4%) in III-IV CCS class. In 145 patients (48.5%) coronary arteriograhy had been performed during hospitalzation. In all patients eGFR estimation was done before any procedures by CG formula, as well as by the MDRD abbreviated equation. Then MDRD equation was compared with the CG formula to detect patients with renal impairment (GFR < 60 ml/min/1.73 m²). Results The mean CG and MDRD estimated GFR were 83.5 ± 30.4 ml/min/1.73 m² and 76.7 ± 23.4 ml/min/1.73 m², respectively. Moderate renal impairment (< 60 ml/ /min/1.73 m²) was observed in 92 pts by CG formula vs. 110 pts by MDRD one (p < 0.05). Acc. to CG 3.7% patients had severe renal impairment (< 30 ml/min/1.73 m²) versus 9.0% with the MDRD equation (p < 0.01). Negative correlations (p < 0.05) between eGFR, both MDRD (r = -0.61) and CG (r = -0.52), and CCS class of CAD, as well as age (r = -0.68 and r = -0.65, respectively) were found in both sexes. In study group, the MDRD thresholds that would correspond to CG values of 30 ml/min and 60 ml/min were found lower: 8 ml/min/1.73 m² and 6 ml/ /min/1.73 m², respectively. In 145 subjects who underwent coronarography lowest eGFR was found in those with three-vessel CAD.
Conclusions In hypertensive patients with CAD, eGFR values derived from MDRD equations identifies significantly higher numbers of individuals with chronic kidney disease then assessed by CG formula. The frequency of renal impairment arises with age and longevity of hypertension and CAD, as well as type 2 diabetes.