Relationship between low cardiorespiratory fitness and mortality in normal-weight, overweight, and obese men

Context Recent guidelines for treatment of overweight and obesity include r ecommendations for risk stratification by disease conditions and cardiovasc ular disease (CVD) risk factors, but the role of physical inactivity is not prominent in these recommendations. Objective To quantify the influence of low cardiorespiratory fitness, an ob jective marker of physical inactivity, on CVD and all-cause mortality in no rmal-weight, overweight, and obese men and compare low fitness with other m ortality predictors. Design Prospective observational data from the Aerobics Center Longitudinal Study. Setting Preventive medicine clinic in Dallas, Tex. Participants A total of 25 714 adult men (average age, 43.8 years [SD, 10.1 years]) who received a medical examination during 1970 to 1993, with morta lity follow-up to December 31, 1994, Main Outcome Measures Cardiovascular disease and all-cause mortality based on mortality predictors (baseline CVD, type 2 diabetes mellitus, high serum cholesterol level, hypertension, current cigarette smoking, and low cardio respiratory fitness) stratified by body mass index. Results During the study period, there were 1025 deaths (439 due to CVD) du ring 258 781 man-years of follow up. Overweight and obese men with baseline CVD or CVD risk factors were at higher risk for all-cause and CVD mortalit y compared with normal-weight men without these predictors. Using normal-we ight men without CVD as the referent, the strongest predictor of CVD death in obese men was baseline CVD (age- and examination year-adjusted relative risk [RR], 14.0; 95% confidence interval [CI], 9.4-20.8); RRs for obese men with diabetes mellitus, high cholesterol, hypertension, smoking, and low f itness were similar and ranged from 4.4 (95% CI, 2.7-7.1) for smoking to 5. 0 (95% CI, 3.6-7.0) for low fitness. Relative risks for all-cause mortality in obese men ranged from 2.3 (95% CI, 1.7-2.9) for men with hypertension t o 4.7 (95% CI, 3.6-6.1) for those with CVD at baseline. Relative risk for a ll-cause mortality in obese men with low fitness was 3.1 (95% CI, 2.5-3.8) and in obese men with diabetes mellitus 3.1 (95 % CI, 2.3-4.2) and as sligh tly higher than the RRs for obese men who smoked or had high cholesterol le vels. Low fitness was an independent predictor of mortality in all body mas s index groups after adjustment for other mortality predictors. Approximate ly 50% (n = 1674) of obese men had low fitness, which led to a population-a ttributable risk of 39% for CVD mortality and 44% for all-cause mortality. Baseline CVD had population attributable risks of 51% and 27% for CVD and a ll-cause mortality, respectively. Conclusions In this analysis, low cardiorespiratory fitness was a strong an d independent predictor of CVD and all-cause mortality and of comparable im portance with that of diabetes mellitus and other CVD risk factors.