Cardiorespiratory Fitness and Mortality in Patients Aged 60 to 90 Years

Chronological age alone does not fully reflect a patient's prognosis. We sought to assess the association of cardiorespiratory fitness (quantified by METs) with all-cause mortality among patients aged 60 to 90 years. This retrospective study included patients who underwent exercise treadmill testing at an integrated healthcare system from 2011 to 2019. Patients were categorized into age groups: 60 to <70 years, 70 to <80 years, and 80 to 90 years; and cardiorespiratory fitness level: low (<5 METs), moderate (5 to 10 METs), and high fitness (>10 METs). Mean follow-up was 3.5 years. A total of 40,520 patients were included (mean age 67.7 ± 4.7 years, 48.6% women). Of whom, 27,021 were 60 to <70 years old (66.7%); 12,638 70 to <80 years old (31.2%); and 1,861 80 to 90 years old (4.6%). There were 3,494 patients categorized as low (8.6%), 21,863 as moderate (54%), and 15,163 as high fitness (37.4%). Low fitness level was independently associated with lower survival (hazard ratio [HR] 1.61, 95% confidence interval [CI] 1.15 to 2.24). Using age 60 to 70 group with high fitness level as reference, the age 80 to 90 group with high fitness level had better survival than their younger counterparts with low fitness level (age 80 to 90 years high fitness level: HR 2.9, 95% CI 1.2 to 7.2; age 60 to 70 years low fitness level: HR 4.3, 95% CI 3.1 to 5.9; age 70 to 80 years low fitness level: HR 6.8, 95% CI 5.2 to 8.9) on adjusted analysis. In conclusion, higher cardiorespiratory fitness is associated with better survival. Patients >80 years old with high fitness level have comparable or even better survival than their younger counterparts with submoderate fitness levels. Chronological age alone should not be the only factor when considering prognosis.