Abstract 16663: The Interaction of Framingham Risk Score and Exercise Capacity for the Prediction of All-Cause Mortality: The FIT Project
Background: The Framingham Risk Score (FRS) is used clinically to categorize patients into risk groups that guide pharmacologic treatment decisions. Exercise capacity is also a powerful marker of future risk but is used less often for risk stratification in clinical practice. We examined the influence of exercise capacity, as measured by metabolic equivalents (METs), on the ability of the FRS to predict all-cause mortality.
METHODS: We studied a retrospective cohort of 52,515 participants (53 ± 13 yrs, 50% men, 31% African American) without CAD or CHF who underwent treadmill stress testing between 1991 and 2009 at a single center. The FRS was calculated using the 1998 equation and METS achieved was categorized as <6, 6-10, 10-12, or >12. We calculated multivariable Cox proportional hazard models and crude mortality rates per 1,000 person-years of follow-up.
RESULTS: There were 5,897 deaths during a mean follow-up of 11±5 years. Mean FRS was 12±10%; mean METs achieved was 9+3. The highest mortality was observed in those with FRS>20% and <6 METs (figure), whereas those with FRS<10% and >12 METs had the lowest mortality. Among individuals with FRS <10%, adjusted hazard ratios for total mortality with increasing exercise capacity were 0.43 (95% CI: 0.38, 0.48) for 6-9 METs, 0.23 (0.20, 0.27) for 10-12 METs and 0.12 (0.10, 0.15) for >12 METs compared with individuals with <6 METs. Among those with a FRS >20%, hazard ratios for total mortality with increasing exercise capacity were 0.53 (0.48, 0.59) for 6-9 METs, 0.28 (0.25, 0.32) for 10-12 METs and 0.20 (0.16, 0.26) for >12 METs, compared with <6 METs. Individuals with FRS<10% and <6 METs had a 3.4-fold higher total mortality rate than individuals with FRS>20% and >12 METs (26.1 versus 7.6 per 1000 person-years).
Conclusions: These findings suggest that higher exercise capacity is associated with reduced mortality risk, independent of FRS. Exercise capacity may represent a valuable tool for additional risk stratification beyond the FRS alone.
- © 2013 by American Heart Association, Inc.