Nonexercise Estimated Cardiorespiratory Fitness and Mortality Due to All Causes and Cardiovascular Disease: The NHANES III Study

OBJECTIVE: To investigate associations of estimated cardiorespiratory fitness (eCRF) and all-cause and cardiovascular disease (CVD) mortality in a representative US population. PARTICIPANTS AND METHODS: A total of 12,834 participants, aged 20 to 86 years at baseline, were included in the Third National Health and Nutrition Examination Survey. They were followed up from October 18, 1988, through December 31, 2011, for all-cause and CVD death. Cardiorespiratory fitness was estimated from a nonexercise algorithm and further grouped into tertiles. Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% CIs. RESULTS: A total of 3439 deaths (999 due to CVD) occurred during median follow-up of 19.2 years. After adjusting for race/ethnicity, education, age, hypertension, diabetes, hypercholesterolemia, baseline CVD, and cancer status, each metabolic equivalent increase of eCRF was associated with an 18% (range, 15%-21%) lower risk of all-cause mortality and a 19% (range, 15%-24%) lower risk of CVD mortality in men and a 24% (range, 20%-28%) lower risk of all-cause mortality and a 24% (18%-30%) lower risk of CVD mortality in women. Compared with the lower eCRF group, the HRs (95% CIs) of the middle and upper groups were 0.72 (0.61-0.85) and 0.56 (0.47-0.67) for all-cause mortality and 0.76 (0.57-1.01) and 0.48 (0.34-0.66) for CVD mortality in men; and 0.80 (0.66-0.97) and 0.49 (0.40-0.60) for all-cause mortality and 0.84 (0.60-1.17) and 0.46 (0.33-0.66) for CVD mortality in women (trend P<.001 for all). CONCLUSION: High eCRF was associated with lower risk of all-cause and CVD mortality in a national representative population. The eCRF method has great potential for initial clinical risk stratification and mortality prediction.