Lifetime Risks for Cardiovascular Disease Mortality by Cardiorespiratory Fitness Levels Measured at Ages 45, 55, and 65 Years in Men: The Cooper Center Longitudinal Study
What is the association between fitness in middle-aged men and lifetime risk for cardiovascular disease (CVD)?
A total of 11,049 men (age range, 45-69 years) who underwent clinical examination at the Cooper Institute in Dallas, TX, before 1990, were followed until the occurrence of CVD death, non-CVD death, or attainment of age 90 years. Fitness was measured by the Balke protocol and categorized according to treadmill time into low, moderate, and high fitness, with further stratification by CVD risk factor burden. Lifetime risk for CVD death determined by the National Death Index was estimated for fitness levels measured at ages 45, 55, and 65 years, with non-CVD death as the competing event.
There was a total of 281,469 person-years of follow-up, with a median follow-up 25.3 years, during which there were 1,106 CVD deaths. Differences in fitness levels (low fitness vs. high fitness) were associated with marked differences in the lifetime risks for CVD death at each index age: age 45 years, 13.7% versus 3.4%; age 55 years, 34.2% versus 15.3%; and age 65 years, 35.6% versus 17.1%. These associations were strongest among persons with CVD risk factors. The combination of high fitness with a high traditional risk factor burden was associated with a lifetime risk for CVD death that was comparable to that of a person with low-risk burden.
The authors concluded that a single measurement of low fitness in mid-life was associated with higher lifetime risk for CVD death, particularly among persons with a high burden of CVD risk factors.
The definition of low fitness at age 45 years was 8.4 METs, and at 65 years was 5.9 METs. High fitness at 45 years was 10.8 METs, and at age 65 years was 8.3 METs. Examples of 5 METs would be slow swimming or square dancing, 8 METs includes jogging and heavy calisthenics, and 10 METs is running at 6 mph. While routine stress testing is not a cost-effective strategy for risk assessment, this study adds to the evidence that stress testing in middle-aged men at intermediate risk for CVD is a reasonable strategy.
Keywords: Follow-Up Studies, Middle Aged, Cardiovascular Diseases, Running, Gymnastics, Risk Assessment, Swimming, Exercise Test
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