Cardiorespiratory fitness as a predictor of nonfatal cardiovascular events in asymptomatic women and men

Abstract

Prospective data relating cardiorespiratory fitness (CRF) with nonfatal cardiovascular disease (CVD) events are limited to studies in men or studies of combined fatal and nonfatal CVD endpoints. The authors examined the association between CRF and nonfatal CVD events in 20,728 men and 5,909 women without CVD at baseline. All participants performed a maximal treadmill exercise test and completed a follow-up health survey in the Aerobics Center Longitudinal Study (Dallas, Texas) between 1971 and 2004. There were 1,512 events in men and 159 events in women during an average follow-up of 10 years. Across incremental CRF groups, age- and examination year-adjusted event rates per 10,000 person-years were 107.9, 75.2, and 50.3 in men (p(trend) < 0.001) and 41.9, 27.7, and 20.8 in women (p(trend) = 0.002). After further adjustment for smoking, alcohol intake, family history of CVD, and abnormal exercise electrocardiogram responses, hazard ratios were 1.00 (referent), 0.82 (95% confidence interval (CI): 0.72, 0.94), and 0.61 (95% CI: 0.53, 0.71) in men, p(trend) < 0.001, and were 1.00 (referent), 0.74 (95% CI: 0.49, 1.13), and 0.63 (95% CI: 0.40, 0.98) in women, p(trend) = 0.05. After adjustment for other CVD predictors, the association remained significant in men but not in women.

Figure 1

Age and examination year adjusted rates of total CVD events (per 10,000 person-years) by levels of CRF and number of major CVD risk factors (current smoking, hypertension, hypercholesterolemia, diabetes, and family history of CVD) in 20,728 men, Aerobics Center Longitudinal Study, Dallas, Texas, 1971-2004. White bars represent low fitness, striped bars moderate fitness, and black bars high fitness. The p values are for a test of linear trend across CRF groups. The number of men (and cases) in the low, moderate, and high CRF groups were 878 (42), 2,886 (143), and 4,099 (154) in those with 0 risk factors; 1,548 (120), 3,422 (266), and 3,131 (226) in those with 1 risk factor; and 1,541 (183), 1,987 (255), and 1,236 (123) in those with ≥2 risk factors. CRF, cardiorespiratory fitness; CVD, cardiovascular disease.

Figure 2

Age and examination year adjusted rates of total CVD events (per 10,000 person-years) by levels of CRF and number of major CVD risk factors (current smoking, hypertension, hypercholesterolemia, diabetes, and family history of CVD) in 5,909 women, Aerobics Center Longitudinal Study, Dallas, Texas, 1971-2004. White bars represent low fitness, striped bars moderate fitness, and black bars high fitness. The p values are for a test of linear trend across CRF groups. The number of women (and cases) in the low, moderate, and high CRF groups were 355 (8), 1,068 (21), and 1,690 (25) in those with 0 risk factors; 349 (14), 725 (22), and 963 (24) in those with 1 risk factor; and 178 (13), 303 (20), and 278 (12) in those with ≥2 risk factors. CRF, cardiorespiratory fitness; CVD, cardiovascular disease.