Cardiorespiratory Fitness and Classification of Risk of Cardiovascular Disease Mortality

University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9047, USA.
Circulation (Impact Factor: 14.43). 03/2011; 123(13):1377-83. DOI: 10.1161/CIRCULATIONAHA.110.003236
Source: PubMed


Cardiorespiratory fitness (fitness) is associated with cardiovascular disease (CVD) mortality. However, the extent to which fitness improves risk classification when added to traditional risk factors is unclear.
Fitness was measured by the Balke protocol in 66 371 subjects without prior CVD enrolled in the Cooper Center Longitudinal Study between 1970 and 2006; follow-up was extended through 2006. Cox proportional hazards models were used to estimate the risk of CVD mortality with a traditional risk factor model (age, sex, systolic blood pressure, diabetes mellitus, total cholesterol, and smoking) with and without the addition of fitness. The net reclassification improvement and integrated discrimination improvement were calculated at 10 and 25 years. Ten-year risk estimates for CVD mortality were categorized as <1%, 1% to <5%, and ≥5%, and 25-year risk estimates were categorized as <8%, 8% to 30%, and ≥30%. During a median follow-up period of 16 years, there were 1621 CVD deaths. The addition of fitness to the traditional risk factor model resulted in reclassification of 10.7% of the men, with significant net reclassification improvement at both 10 years (net reclassification improvement=0.121) and 25 years (net reclassification improvement=0.041) (P<0.001 for both). The integrated discrimination improvement was 0.010 at 10 years (P<0.001), and the relative integrated discrimination improvement was 29%. Similar findings were observed for women at 25 years.
A single measurement of fitness significantly improves classification of both short-term (10-year) and long-term (25-year) risk for CVD mortality when added to traditional risk factors.

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    • "For over 50 years, human research has used graded maximal exercise testing (GXT h ) as the prototypical method to study cardiovascular and metabolic responses of the body to stress234. These standardized GXT h tests, such as the gold standard Bruce protocol [5, 6], are key non-invasive and cost-effective methods for the assessing patient mortality risks [7, 8] and diagnosing coronary artery disease (CAD) [9]. New therapies for metabolic and cardiovascular disease have fast progressed with the development of genetic mouse models of cardiovascular dysfunction (reviewed in1011121314). "
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    ABSTRACT: Functional assessments of cardiovascular fitness (CVF) are needed to establish animal models of dysfunction, test the effects of novel therapeutics, and establish the cardio-metabolic phenotype of mice. In humans, the graded maximal exercise test (GXT) is a standardized diagnostic for assessing CVF and mortality risk. These tests, which consist of concurrent staged increases in running speed and inclination, provide diagnostic cardio-metabolic parameters, such as, VO2max, anaerobic threshold, and metabolic crossover. Unlike the human-GXT, published mouse treadmill tests have set, not staged, increases in inclination as speed progress until exhaustion (PXT). Additionally, they often lack multiple cardio-metabolic parameters. Here, we developed a mouse-GXT with the intent of improving mouse-exercise testing sensitivity and developing translatable parameters to assess CVF in healthy and dysfunctional mice. The mouse-GXT, like the human-GXT, incorporated staged increases in inclination, speed, and intensity; and, was designed by considering imitations of the PXT and differences between human and mouse physiology. The mouse-GXT and PXTs were both tested in healthy mice (C57BL/6J, FVBN/J) to determine their ability to identify cardio-metabolic parameters (anaerobic threshold, VO2max, metabolic crossover) observed in human-GXTs. Next, theses assays were tested on established diet-induced (obese-C57BL/6J) and genetic (cardiac isoform Casq2-/-) models of cardiovascular dysfunction. Results showed that both tests reported VO2max and provided reproducible data about performance. Only the mouse-GXT reproducibly identified anaerobic threshold, metabolic crossover, and detected impaired CVF in dysfunctional models. Our findings demonstrated that the mouse-GXT is a sensitive, non-invasive, and cost-effective method for assessing CVF in mice. This new test can be used as a functional assessment to determine the cardio-metabolic phenotype of various animal models or the effects of novel therapeutics.
    Full-text · Article · Feb 2016 · PLoS ONE
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    • "Despite being an essential health indicator, VO 2peak is rarely assessed in health care settings[5,6], likely because direct gas analysis measurements of VO 2peak is expensive, necessitate the use of advanced equipment, and trained personnel[2]. However, reliable and valid prediction models should be considered as several studies have shown that either directly measured or estimated VO 2peak enhance CVD-mortality prediction beyond traditional risk factors[7,8]. Although a maximal test is considered a safe practice, complications and adverse effects occur, normally linked to underlying disease[9]. "
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    ABSTRACT: Peak oxygen uptake (VO2peak) is seldom assessed in health care settings although being inversely linked to cardiovascular risk and all-cause mortality. The aim of this study was to develop VO2peak prediction models for men and women based on directly measured VO2peak from a large healthy population
    Full-text · Article · Jan 2016 · PLoS ONE
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    • "CVD is associated with cardiorespiratory fitness morality. Cox proportional hazards models were used to estimated by Gupta et al (2011)the risk of CVD mortality with a traditional risk factor model (age, sex, systolic blood pressure, diabetes mellitus, total cholesterol, and smoking) with and without the addition of fitness. "

    Preview · Article · Jan 2016 · International Journal of Advanced Trends in Computer Science and Engineering
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