Abstract
Objective
To assess the predictive value of estimated cardiorespiratory fitness (eCRF) and evaluate
the additional contribution of traditional risk factors in cardiovascular disease
(CVD) mortality prediction.
Participants and Methods
The study included healthy men (n=18,721) and women (n=19,759) aged 30 to 74 years.
A nonexercise algorithm estimated cardiorespiratory fitness. Cox proportional hazards
models evaluated the primary (CVD mortality) and secondary (all-cause, ischemic heart
disease, and stroke mortality) end points. The added predictive value of traditional
CVD risk factors was evaluated using the Harrell C statistic and net reclassification
improvement.
Results
After a median follow-up of 16.3 years (range, 0.04-17.4 years), there were 3863 deaths,
including 1133 deaths from CVD (734 men and 399 women). Low eCRF was a strong predictor
of CVD and all-cause mortality after adjusting for established risk factors. The C
statistics for eCRF and CVD mortality were 0.848 (95% CI, 0.836-0.861) and 0.878 (95%
CI, 0.862-0.894) for men and women, respectively, increasing to 0.851 (95% CI, 0.839-0.863)
and 0.881 (95% CI, 0.865-0.897), respectively, when adding clinical variables. By
adding clinical variables to eCRF, the net reclassification improvement of CVD mortality
was 0.014 (95% CI, −0.023 to 0.051) and 0.052 (95% CI, −0.023 to 0.127) in men and
women, respectively.
Conclusion
Low eCRF is independently associated with CVD and all-cause mortality. The inclusion
of traditional clinical CVD risk factors added little to risk discrimination and did
not improve the classification of risk beyond this simple eCRF measurement, which
may be proposed as a practical and cost-effective first-line approach in primary prevention
settings.
Abbreviations and Acronyms:
BP ( blood pressure), CRF ( cardiorespiratory fitness), CV ( cardiovascular), CVD ( CV disease), eCRF ( estimated CRF), HDL-C ( high-density lipoprotein cholesterol), HUNT ( Nord-Trøndelag Health Study), IDI ( integrated discrimination improvement), IHD ( ischemic heart disease), MET ( metabolic equivalent), NRI ( net reclassification improvement), PA ( physical activity), rHR ( resting heart rate), WC ( waist circumference)To read this article in full you will need to make a payment
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Article Info
Publication History
Published online: November 17, 2016
Footnotes
Grant Support: This work was supported in part by grants from the K.G. Jebsen Foundation (J.N., B.M.N., U.W.), the Research Council of Norway (U.W.), the Liaison Committee between the Central Norway Regional Health Authority and the Norwegian University of Science and Technology (J.N.), and the University of Queensland, Australia (J.S.C.).
Identification
Copyright
© 2016 Mayo Foundation for Medical Education and Research
