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); coef exp(coef) e(coef) z p eGFR_BASE 6.40 603.5133 0.3702 17.3 0 eGFR_BASE:TIME -3.41 0.0329 0.0772 -44.2 0 But the result seems very different from that got by SPSS: B SE Wald df Sig. Exp(B) eGFR_BASE -13.603 .548 616.007 1 .000 .000 T_COV_*eGFR_BASE .860 .115 55.859 1 .000 2.362 so my questions are : 1, Is it correct to deal with time dependent covariate in Cox regression using R? if not, how to do it ? 2, How T_COV_ was calculated in SPSS, and is it the same with the survival time? Many thanks. GZ [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.