Abstract 16899: Change in Cardiorespiratory Fitness is Inversely Related to Mortality Among Black and White Patients: Data From the Henry Ford Exercise Testing (FIT) Project
Background: Cardiorespiratory fitness (CRF) is inversely related to all-cause mortality and cardiovascular-related morbidity and mortality. However, there is limited data describing whether change in CRF is associated with improved outcomes.
Hypothesis: Change in CRF between two clinical exercise stress tests is related to risk of all-cause mortality.
Methods: In this retrospective, observational study, we identified 14,305 patients (age = 55 ± 11 y; 39% women; 30% non-white) who completed two clinically-indicated exercise tests that were at least 12 mo apart between 1991 and 2009 within the Henry Ford Health System. CRF was quantified in metabolic equivalents of task (METs) estimated from peak treadmill speed and grade. All-cause mortality was identified through April 2013 using the Social Security Death Index. Cox regression analysis was used to evaluate the risk of mortality associated with change in CRF between tests 1 and 2. Change in CRF was analyzed as the change in categorization between Poor Fitness (<7 METs) and Fit (≥ 7 METs) and as an absolute change in peak METs. Based on data at test 1, covariates included age; sex; race; cardiovascular risk factors; medications; and history of coronary artery disease, heart failure, and atrial fibrillation; as well as year of test 1 and years between tests 1 and 2.
Results: The mean time between test 1 and 2 was 4.3 ± 2.8 y. During 9.4 ± 3.9 y of follow-up after test 2, there were 1,980 (14%) deaths. Adjusted Cox regression results are shown in the Table. Among all patients, each 1 MET increase in CRF at test 2 was associated with a 5% lower risk of mortality (hazard ratio 95% confidence interval 0.94, 0.97; p < 0.001).
Conclusions: Among men and women referred for a clinical exercise test, change in CRF from Poor Fitness to Fit is associated with a 38% lower risk of all-cause mortality relative to patients who remain Unfit. These data support the importance of improving CRF and the clinical utility of serial assessments of CRF in risk assessment.
Author Disclosures: J.K. Ehrman: None. C.A. Brawner: None. M.H. Al-Mallah: None. W.T. Qureshi: None. J.R. Schairer: None. M.J. Blaha: None. S.J. Keteyian: None.
- © 2015 by American Heart Association, Inc.