title: Association between VO₂ peak estimated by a 1-km treadmill walk and mortality. A 10-year follow-up study in patients with cardiovascular disease.
abstract: OBJECTIVE
  The aim of this study is to assess the association between peak oxygen uptake (VO2 peak), determined using a perceptually regulated 1-km walking test (1k-TWT), and all-cause mortality in cardiac patients.
  
  
  METHODS
  1255 male patients, aged 25-85 years, completed a moderate 1k-TWT to estimate VO2 peak. Subjects were followed for all-cause mortality for up to 10 years. Cox proportional hazard models were employed to determine variables associated with mortality. Based on the estimated VO2 peak, the sample was subdivided into quartiles and mortality risks were calculated. To assess the discriminatory accuracy of the estimated VO2 peak for estimating survival, receiver-operating-characteristics curves were constructed.
  
  
  RESULTS
  During a median 8.2 year follow-up, a total of 141 deaths from any cause occurred, yielding an average annual mortality of 1.4%. The strongest predictor of all-cause mortality was the estimated VO2 peak (c-statistic 0.71, 95% confidence intervals: 0.69-0.74, P<0.0001). Survival decreased in a graded fashion from the highest estimated VO2 peak quartile to the lowest quartile. Compared to the lowest quartile, the hazard ratios (95% confidence intervals) for the second, third, and fourth quartiles were 0.77 (0.35-1.33), 0.43 (0.20-0.91), and 0.16 (0.05-0.54) respectively (P for trend <0.0001). An 89% reduction in mortality risk was observed among a subset of subjects in the fittest quartile who improved their estimated VO2 peak over the follow-up period relative to subjects in the least fit quartile who did not improve.
  
  
  CONCLUSIONS
  VO2 peak estimated by a novel 1k-TWT predicts survival in subjects with stable cardiovascular disease.
authors.affiliation: Cardiac Rehabilitation and Prevention Program, Public Health Department, AUSL Ferrara, Ferrara, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Grazzi
authors.affiliation: Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Myers
authors.affiliation: Cardiac Rehabilitation and Prevention Program, Public Health Department, AUSL Ferrara, Ferrara, Italy. Electronic address: bernardi.eva@gmail.com.
authors.forename: Eva
authors.initials: E
authors.lastname: Bernardi
authors.affiliation: Cardiac Rehabilitation and Prevention Program, Public Health Department, AUSL Ferrara, Ferrara, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Terranova
authors.affiliation: Cardiac Rehabilitation and Prevention Program, Public Health Department, AUSL Ferrara, Ferrara, Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Grossi
authors.affiliation: Cardiac Rehabilitation and Prevention Program, Public Health Department, AUSL Ferrara, Ferrara, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Codecà
authors.affiliation: Department of Clinical and Experimental Medicine, University of Ferrara, Ferrara, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Volpato
authors.affiliation: Cardiac Rehabilitation and Prevention Program, Public Health Department, AUSL Ferrara, Ferrara, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Conconi
authors.affiliation: Cardiac Rehabilitation and Prevention Program, Public Health Department, AUSL Ferrara, Ferrara, Italy.
authors.forename: Gianni
authors.initials: G
authors.lastname: Mazzoni
authors.affiliation: Cardiac Rehabilitation and Prevention Program, Public Health Department, AUSL Ferrara, Ferrara, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Chiaranda
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000378:metabolism / Q000401:mortality; D005080:Exercise Test; D017079:Exercise Tolerance; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010101:Oxygen Consumption / Q000502:physiology*; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012372:ROC Curve; D012307:Risk Factors; D016138:Walking
keywords: Cardiac patients; Mortality; VO(2) peak