Metabolic Syndrome, Cardiorespiratory Fitness and the Risk of All-cause and Cardiovascular Mortality in Men: A Long-Term Prospective Cohort Study

Abstract

Background and Objectives: Cardiorespiratory fitness (CRF) ameliorates the increased risk of cardiovascular disease and mortality attributed to various risk factors. It is unclear whether the cardioprotective effects of CRF extend to attenuating the mortality risk associated with metabolic syndrome (MetS), which comprises a cluster of cardiometabolic risk factors. The purpose of this study was to examine the individual and joint associations of CRF and MetS with the risk of all-cause mortality and cardiovascular mortality. Methods: This prospective study was based on a general population sample of 1,711 men in the Kuopio Ischemic Heart Disease cohort study. MetS was defined using the National Cholesterol Education Program criteria. CRF was directly measured as peak oxygen uptake during maximal exercise testing. Results: During a median of 26 years follow-up, 799 all-cause mortality and 376 cardiovascular mortality events occurred. Men with MetS had a 41% increased risk of all-cause mortality and 76% increased risk of cardiovascular mortality in multivariable analysis, while men with upper levels of CRF demonstrated a 41% and 50% decreased risk of all-cause mortality and cardiovascular mortality, respectively, following adjustment for potential confounders. For the joint associations of MetS and CRF with the risk of outcomes, fit with MetS were at increased risks of death (all-cause mortality, hazard ratio [HR], 1.73; 95% confidence interval [CI], 1.42–2.11; cardiovascular mortality, HR, 2.29; 95% CI, 1.71–3.07) compared with fit without MetS. Conclusions: Although these results suggest that MetS and CRF were each independently associated with the risk of death, the latter did not eliminate the heightened risk of death associated with the former.