Change in Maximal Exercise Capacity Is Associated With Survival in Men and Women

Objective To describe the relationship between change in maximal exercise capacity (MEC) over time and risk of all-cause mortality separately in men and women. Patients and Methods Consecutive patients (n=10,854; mean ± SD age, 54±11 years; 43% women; 30% nonwhite) who completed 2 physician-referred exercise tests between January 2, 1991, and May 28, 2009, were identified from the Henry Ford Exercise Testing (FIT) Project. The MEC was quantified in metabolic equivalents of task (METs) calculated from peak workload on a treadmill and adjusted to the equivalent for a 50-year-old man. Multivariable Cox proportional hazards regression was performed to assess risk of all-cause mortality associated with change in MEC based on (1) change from age-/sex-adjusted low fitness (<8 METs) to intermediate or high fitness and (2) an absolute change in METs. Results Relative to patients with low fitness at both tests, increasing from low to intermediate or high fitness was associated with lower risk of all-cause mortality (adjusted hazard ratio [aHR] = 0.63 [95% CI, 0.45-0.87] in men and 0.56 [95% CI, 0.34-0.91] in women). Each 1-MET increase in age-/sex-adjusted MEC between baseline and follow-up was associated with an aHR of 0.87 (95% CI, 0.84-0.91) in men and 0.84 (95% CI, 0.79-0.89) in women, with no significant interaction by sex (P=.995). Similar aHRs were observed in a subgroup with intermediate fitness at baseline. Conclusion In men and women referred for an exercise stress test, change in MEC over time is inversely related to risk of all-cause mortality.