Cardiorespiratory Fitness, Different Measures of Adiposity, and Cardiovascular Disease Mortality Risk in Women

Background: Associations among cardiorespiratory fitness (CRF), different adiposity exposures, and cardiovascular disease (CVD) mortality in women are not well defined. Materials and Methods: A total of 19,838 women completed a baseline examination between 1971 and 2013. Measures included body mass index (BMI), waist circumference (WC), waist-to-height (W:HT) ratio, skinfold-derived percent body fat (% Fat), and CRF estimated from a maximal treadmill test. CRF categories were low (quintile 1), moderate (quintiles 2-3), and high (quintiles 4-5); standard cut points were used for adiposity exposures. Hazard ratios (HRs) were estimated using Cox regression. Results: During a mean follow-up period of 19.2 +/- 10.3 years, 391 cardiovascular deaths occurred. HRs (95% confidence interval) for CVD in moderate and low CRF groups, using high CRF as the referent, were 1.87 (1.46-2.38) and 2.54 (1.93-3.35), respectively (p trend <0.001). HRs of obese women within each adiposity exposure were higher when compared with normal-weight women (p <= 0.03). Joint associations of CRF x adiposity showed a positive trend in CVD mortality across decreasing categories of CRF within each category of W:HT and % Fat, as well as within the normal and overweight BMI categories and the normal WC category (p <= 0.03 for each). Conclusion: Higher levels of CRF are associated with lower CVD mortality risk in women, and predict lower risk of CVD mortality in normal-weight women and in obese women. Using different measures of adiposity to predict CVD mortality risk in women may be misleading unless CRF is taken into account. These results support the American Heart Association (AHA) recommendation for including CRF as a clinical vital sign.