search for: fitagecovariate

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2007 Feb 05
2
Two ways to deal with age in Cox model
...including age as a covariate, or to include age as part of the follow-up time, viz, Age as a covariate: tetest1 <- list(time= c(4, 3,1,1,2,2,3), status=c(1,NA,1,0,1,1,0), age= c(0, 2,1,1,1,0,0), riskfactor= c(0, 0,0,0,1,1,1)) fitagecovariate<-coxph( Surv(time, status) ~ age +riskfactor, test1) fitagecovariate Age included as part of follow-up time: test2<-test1 test2$timeplusage<-test2$time+test2$age fitagefollowup<-coxph( Surv(timeplusage, status) ~ riskfactor, test2) fitagefollowup I would appreciate any thoughts...