Figure 3

Number of step-ups completed in 10 seconds. The number of step-ups completed in 10 seconds was the best single-variable predictor of short and long-term survival (mean C = 0.589). Part (A) shows the time-specific ROC curve corresponding to 10-years of follow-up time. Estimates of sensitivity and specificity were calculated as described in Methods and averaged among simulation trials. The dashed line corresponds to the null expectation with an AUC value of 0.50. Part (B) plots estimated values of AUC(t) across t = 1,..., 19 years of follow-up time. Each point represents the average value of AUC(t) among 10,000 simulation trials, and error bars indicate the standard deviation of AUC(t) among simulations. The solid red line indicates the mean concordance index of 0.589 among simulations, and dashed red lines represent one standard deviation above and below the mean concordance estimate.