Cardiorespiratory Fitness Impact on All-Cause Mortality in Prediabetic Veterans

Abstract

Background: The objective of this study was to evaluate the role of cardiorespiratory fitness (CRF) on all-cause mortality in prediabetic veterans. Methods: In this prospective cohort study, CRF was calculated from metabolic equivalents (METs) obtained from routine exercise tolerance testing in a cohort of 1,118 prediabetic veterans. Four fitness categories were established: low-fit (< 5.8 METs; lower 25th percentile), mild-fit (5.8 - 7 METs), moderate-fit (7.1 - 8.5 METs) and high-fit (> 8.5 METs; > 75th percentile). Date of death was verified from the Veterans Affairs Beneficiary Identification and Record Locator System File. Results: The mean follow-up period was 7.7 years (8,610 person-years) and there were a total of 251 deaths, averaging 29.1 events per 1,000 person-years. An inverse and graded association between CRF and mortality risk was observed (P = 0.002). For every 1-MET increase in CRF, the adjusted mortality was lowered by 13% (hazard ratios (HR) = 0.87; CI: 0.81 - 0.94, P < 0.001). The mild-, moderate- and high-Fit subjects had mortality reductions of 32% (HR = 0.68; CI: 0.50 - 0.94, P = 0.02), 40% (HR = 0.60; CI: 0.41 - 0.87, P = 0.007) and 54% (HR = 0.46; CI: 0.30 - 0.70, P < 0.001) respectively. Conclusions: A strong inverse and graded association between CRF and mortality risk was observed in these prediabetic veterans. Mortality risk was 13% lower for every 1-MET increase in CRF and approximately 50% lower in high-fit individuals (exercise capacity > 8.5 METs) compared to least-fit individuals. With increasing incidence of prediabetes as well as diminished response to preventative lifestyle modifications, enhanced CRF should be advocated in prediabetic individuals. J Endocrinol Metab. 2015;5(3):215-219 doi: http://dx.doi.org/10.14740/jem284w