I am working on finding the optimum follow-up interval for a failure outcome. My data is survival data including a time variable and an event variable and a number of exposure variables. I was wondering if I can set up the ROC curve by placing time-to-follow-up as the exposure variable and the event as the classifying variable, and then take the optimum cutoff point of this ROC curve as the optimum follow-up interval to best screen my future subjects?