Estimated glomerular filtration rate as an independent predictor of atherosclerotic vascular disease in older women

Abstract

Background: Estimated glomerular filtration rate (eGFR) levels have been shown to predict atherosclerotic vascular disease hospitalization and mortality. We sought to investigate the role of renal function in the prediction of 10-year atherosclerotic vascular hospitalization and deaths in an unselected population of elderly women and compared these predictions to Framingham equations.

Methods: Complete 10-year verified mortality and hospitalization discharge records for atherosclerotic vascular disease were collected for a prospective study of 1,239 unselected female subject's ≥ 70 from the Calcium Intake Fracture Outcome Study (CAIFOS) with 10 years of follow-up. eGFR was compared to the current Framingham risk scores.

Results: The eGFR at baseline using the Modification of Diet in Renal Disease Study (MDRD) equation was 65.2 ± 14.5 mL/min/1.73 m(2) and 66.3 ± 13.5 mL/min/1.73 m(2) using the Chronic Kidney Disease EPIdemiology (CKD-EPI) equation. Over 10 years 30% of participants sustained an ASVD hospitalization or death. For every standard deviation (SD) reduction in eGFR using MDRD the odds ratio (OR) for ASVD hospitalization and deaths increased by 1.34 (1.18-1.53), P < 0.00 and 1.31 (1.14-1.50), P < 0.001 in a model adjusted for Framingham 10-year general cardiovascular risk. Addition of eGFR by the MDRD equation to Framingham risk factors improved the net reclassification index by 5.9%, P = 0.018 and the integrated discrimination improvement by 0.010 ± 0.003, P < 0.001 Similar results were seen using the CKD-EPI equation.

Conclusion: Estimated glomerular filtration rate predicts ASVD outcomes independently of Framingham risk score predictions in elderly women and improves clinical prediction particularly of early ASVD.

Figure 1

Kaplan Meier survival curves for ASVD hospitalizations and deaths dichotomized by a) K/DOQI chronic kidney disease categories of eGFR by the MDRD equation; blue line <45 mL/min/1.73 m²(n = 71), green line 45–59 mL/min/1.73 m²(n = 388), grey line 60–89 mL/min/1.73 m²(n = 722) and black line ≥90 mL/min/1.73 m²(n = 58) and b) Framingham predicted risk, blue line ≥30% 10-year risk (n = 128), green line 15-29% 10-year risk (n = 649) and grey line <15% 10-year risk (n = 427).

Figure 2

Framingham risk score-adjusted odds ratio and 95% confidence interval per 10 ml/min/1.73 m² decrease in eGFR in the whole cohort and those free of ASVD at baseline. ASVD atherosclerotic vascular disease, eGFR estimated glomerular filtration rate, MDRD Modification.