Comparative prognostic value of glomerular filtration rate estimating formulas in ischaemic heart disease

Background Chronic kidney disease is a major risk factor for cardiovascular death and may be detected by measuring serum creatinine levels (SCr). Alternatively, renal function may be evaluated by estimating glomerular filtration rate (GFR)with formulas based on SCr and variables such as age, sex and body weight. The purpose of the study was to compare the predictive value of GFR, calculated with the Cockcroft-Gault (CG) and revised Modification of Diet in Renal Disease formulas, in a population with ischaemic heart disease (IHD). Design Retrospective observational study. Methods Renal function was analysed in 1705 patients (mean age 55± 9.2 years, 80% male) who had been admitted to our Institute for IHD. The relationship between reduced GFR and outcome was examined through Kaplan-Meier curves and Cox regression analysis. Results Ten-year mortality was 20% and had as predictors both an abnormal (Z1.10 mg/dl) SCr and reduced ( 60 ml/ min/1.73m2) Modification of Diet in Renal Disease and CG GFR (P 0.0001 for each). Using Cox regression analysis, significant coronary atherosclerosis, defined as a greater than 50% stenosis in at least one major vessel, turned out to be the factor most closely linked to increased mortality [HR corresponds to hazard ratio 4.40, 95% (confidence interval) CI 2.78-6.97, P 0.001], followed by reduced CG GFR (HR 2.08, 95% CI 1.55-2.79, P 0.001) and left bundle branch block (HR 2.00, 95% CI 1.10-3.61, P 0.001). Conclusion GFR, especially if calculated with the CG formula, is an important prognostic indicator for IHD among hospitalized patients, and predicts survival more accurately than SCr and conventional coronary risk factors.