Abstract 58: Age-specific Exercise Capacity Threshold for All-cause Mortality Risk in Men
Introduction: Exercise capacity is inversely associated with mortality risk. However, there is no age-specific standardized exercise capacity threshold to guide clinical assessment of mortality risk.
Hypothesis: We assessed the hypothesis that an age-specific standardized threshold can be defined based on maximal exercise capacity (METs) to assess mortality risk across age groups.
Methods: Peak exercise capacity was assessed in 18,102 men (mean age: 58±11) at DC and Palo Alto CA VA Medical Centers. We stratified the cohort into four age-groups (<50; 50-59; 60-69; and ≥70 yrs of age). We applied Cox proportional hazards models with spline function of MET to define the MET level associated with no increase in mortality risk (hazard ratio (HR)=1.0). We formed five additional age-specific fitness categories based on METs achieved above and below this threshold (T1; n=3,705): T2=T1-2 METs (n=4,884); T3; T1->2 METs (n=1,692); T4=T1+2 METs (n=4,646); T5=T1+2-4 METs (n=1,874) and T6=T1+>4 METs (n=1,301).
Results: The MET thresholds for the aforementioned age groups were identified as 8; 7; 6; and 5 METs, respectively. There were 5,103 deaths (median follow-up=10.8 yrs; 208,108 person-yrs). Cox proportional hazards analysis adjusted for age, cardiac risk factors, medications and muscle-wasting disease revealed 19% (HR=1.19; CI: 1.10-1.28) and 46% (HR=1.46; CI:1.33-1.60) higher all-cause mortality risk for those with exercise capacity 2 and >4 METs below the threshold, respectively. For those with an exercise capacity 2; 4 and >4 METs above the threshold, mortality risk was lower by 27% (HR= 0.73; CI:0.66-0.79), 35% (HR= 0.65; CI: 0.58-0.74), and 48% (HR=0.52; CI:0.45-0.62), respectively (p<0.001 for all comparisons). The trends for mortality risk were similar for each age category (Table).
Conclusions: We identified an age-specific MET threshold for fitness-related clinical assessment of mortality risk in men.
Author Disclosures: P. Kokkinos: None. J. Myers: None. C. Faselis: None. X. Sui: None. J. Zhang: None. S. Blair: None.
- © 2014 by American Heart Association, Inc.