title: Prediction of Cardiovascular Mortality by Estimated Cardiorespiratory Fitness Independent of Traditional Risk Factors: The HUNT Study.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: K.G. Jebsen Center for Exercise in Medicine, Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Javaid
authors.initials: J
authors.lastname: Nauman
authors.affiliation: K.G. Jebsen Center for Exercise in Medicine, Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway. Electronic address: bjarne.nes@ntnu.no.
authors.forename: Bjarne M
authors.initials: BM
authors.lastname: Nes
authors.affiliation: Department of Cardiovascular Diseases, John Ochsner Heart and Vascular Institute, Ochsner Clinical School, University of Queensland School of Medicine, New Orleans, LA.
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Lavie
authors.affiliation: Department of Health and Human Performance, University of Houston, Houston, TX.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Jackson
authors.affiliation: Department of Exercise Science, University of South Carolina, Columbia, SC.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Sui
authors.affiliation: School of Human Movement and Nutrition Sciences, University of Queensland, St. Lucia, Queensland, Australia.
authors.forename: Jeff S
authors.initials: JS
authors.lastname: Coombes
authors.affiliation: Department of Exercise Science, University of South Carolina, Columbia, SC.
authors.forename: Steven N
authors.initials: SN
authors.lastname: Blair
authors.affiliation: K.G. Jebsen Center for Exercise in Medicine, Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Ulrik
authors.initials: U
authors.lastname: Wisløff
mesh_terms: D000328:Adult; D000368:Aged; D000072599:Cardiorespiratory Fitness; D002318:Cardiovascular Diseases / Q000401:mortality*; D002423:Cause of Death; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000401:mortality; D009664:Norway / Q000453:epidemiology; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012042:Registries; D012307:Risk Factors; D020521:Stroke / Q000401:mortality