Abstract 13614: Prognostic Value of Cardiorespiratory Fitness in Patients With Chronic Renal Dysfunction: The FIT (Henry Ford Exercise Testing) Project
Background: Chronic kidney disease (CKD) is associated with high morbidity and mortality. We tested the hypothesis that cardiorespiratory fitness (CRF) retains incremental prognostic value over renal function, as measured by estimated glomerular filtration rate (eGFR).
Methods: Our analysis included 50,121 patients (mean age 55 ± 12.6 years and 47.5% females) from The Henry Ford Exercise Testing Project (FIT project), who underwent exercise stress testing between 1991 and 2009. Patients with heart failure or missing relevant covariate data were excluded. The mean duration between stress testing and creatinine measurement was 30 days and eGFR was estimated using the Modification of Diet in Renal Disease equation. Treadmill stress testing used the standard Bruce protocol and CRF was estimated using metabolic equivalent of task units (MET). Patients were followed-up for all-cause mortality. Multiple nested Cox models were used to determine the incremental prognostic value of CRF over eGFR.
Results: The magnitude of renal dysfunction was inversely associated with (level of CRF (mean METs achieved 9.1, 9.0, 7.5, 5.5 METS for Stage I, II, III and more than III CKD respectively, p<0.0001). Over a median follow-up duration of 6.7 yr, (IQR 3.9 to 10 yr), 6,308 (12.6%) patients died. CRF was a strong, independent predictor of mortality (p <0.001) and at every stage of renal function, improved CRF was associated with improved survival. (figure). Using Cox analysis, CRF added improved discriminatory ability beyond traditional risk factors and renal function: Area under the curve (AUC) 0.837 (95% CI 0.832 - 0.842) vs. 0.814 (95% CI 0.809 - 0.8198), respectively, p-value <0.0001. Renal function did not add incremental prognostic value once CRF was accounted for.
Conclusion: Regardless of renal function, CRF is an independent predictor of mortality. Fitness adds incremental prognostic value over renal function in this large diverse clinical cohort.
Author Disclosures: A. Ahmed: None. W.T. Qureshi: None. C.A. Brawner: None. S.J. Keteyian: None. J.K. Ehrman: None. R.S. Blumenthal: None. K. Nasir: Consultant/Advisory Board; Modest; Regeneron, Quest Diagnostic. Consultant/Advisory Board; Significant; Modest, Modest. M.J. Blaha: None. M.H. Al-Mallah: None.
- © 2015 by American Heart Association, Inc.