如何在R中的coxph函数中指定偏移项，稍后可在；mstate“；包裹

我正在尝试使用R中的mstate包，为此，我必须使用strata命令使用coxph函数。下面是一个示例代码：

library(mstate)
tmat <- trans.illdeath()
tg <- data.frame(stt=rep(0,6),sts=rep(0,6), illt=c(1,1,6,6,8,9),ills=c(1,0,1,1,0,1),
             dt=c(5,1,9,7,8,12),ds=c(1,1,1,1,1,1))
tg$patid <- factor(2:7,levels=1:8,labels=as.character(1:8))
tt <- matrix(c(rep(NA,6),tg$illt,tg$dt),6,3)
st <- matrix(c(rep(NA,6),tg$ills,tg$ds),6,3)
mslong<-msprep(time=tt,status=st,trans=tmat)
models <- coxph(Surv(Tstart, Tstop, status) ~ strata(trans), data=mslong, method='breslow')

库（mstate）
tmat从技术上讲，您可以按如下方式进行：

# define c1 as an indicator for transition 3
mslong$c1<-ifelse(mslong$trans == 3, 1, 0)
model <-coxph(Surv(Tstart, Tstop, status) ~ strata(trans)+offset(2*c1), data=mslong, method='breslow')

偏移模型：

> coxph(Surv(Tstart, Tstop, status) ~ strata(trans)+offset(2*c1), data=mslong, method='breslow')
Call:  coxph(formula = Surv(Tstart, Tstop, status) ~ strata(trans) + 
    offset(2 * c1), data = mslong, method = "breslow")

Null model
  log likelihood= -7.742402 
  n= 16 

非常感谢@thc。您对我如何修改代码有何建议，以便我可以更改过渡=3的累积基线风险？
# define c1 as an indicator for transition 3
mslong$c1<-ifelse(mslong$trans == 3, 1, 0)
model <-coxph(Surv(Tstart, Tstop, status) ~ strata(trans)+offset(2*c1), data=mslong, method='breslow')

> coxph(Surv(Tstart, Tstop, status) ~ strata(trans), data=mslong, method='breslow')
Call:  coxph(formula = Surv(Tstart, Tstop, status) ~ strata(trans), 
    data = mslong, method = "breslow")

Null model
  log likelihood= -7.742402 
  n= 16 

> coxph(Surv(Tstart, Tstop, status) ~ strata(trans)+offset(2*c1), data=mslong, method='breslow')
Call:  coxph(formula = Surv(Tstart, Tstop, status) ~ strata(trans) + 
    offset(2 * c1), data = mslong, method = "breslow")

Null model
  log likelihood= -7.742402 
  n= 16