Association between VO2peak estimated by a 1-Km treadmill walk and mortality. A 10-year follow-up study in patients with cardiovascular disease

Purpose The aim of this study is to assess the association between peak oxygen uptake (VO 2 peak), determined using a perceptually regulated 1-km walking test (1k-TWT), and all-cause mortality in cardiac patients. Methods 1255 male patients, aged 25–85years, completed a moderate 1k-TWT to estimate VO 2 peak. Subjects were followed for all-cause mortality for up to 10years. Cox proportional hazard models were employed to determine variables associated with mortality. Based on the estimated VO 2 peak, the sample was subdivided into quartiles and mortality risks were calculated. To assess the discriminatory accuracy of the estimated VO 2 peak for estimating survival, receiver-operating-characteristics curves were constructed. Results During a median 8.2year 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 VO 2 peak ( c- statistic 0.71, 95% confidence intervals: 0.69–0.74, P 2 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 2 peak over the follow-up period relative to subjects in the least fit quartile who did not improve. Conclusion VO 2 peak estimated by a novel 1k-TWT predicts survival in subjects with stable cardiovascular disease.