Re: [R] Problem of COX model with time dependent covariate

I'll add just a little to what David said. The normal meaning of a "time dependent covariate" is a covariate that changes with time. For instance in a model that included x="most recent available blood pressure" the value of x will change at each patient visit. You obviously can't get those new

Re: [R] Problem of COX model with time dependent covariate

On Dec 26, 2011, at 3:02 AM, JiangGZ wrote: Hi all, I am trying to detect association between a covariate and a disease outcome using R. This covariate shows time-varying effect, I add a time-covariate interaction item to build Cox model as follows: COX <- coxph(as.formula("Surv(TIME,out

[R] Problem of COX model with time dependent covariate

Hi all, I am trying to detect association between a covariate and a disease outcome using R. This covariate shows time-varying effect, I add a time-covariate interaction item to build Cox model as follows: COX <- coxph(as.formula("Surv(TIME,outcome)~eGFR_BASE+eGFR_BASE:TIME"),ori.data);