
Dear all,
 
I am trying to plot KM curves with confidence bands with function survplot under package rms.
 
However, the following codes do not seem to work. The KM curves are produced, but the confidence bands are not there. 
 
Any insights? Thanks in advance.
 
library(rms)
########data generation############
n <- 1000
set.seed(731)
age <- 50 + 12*rnorm(n)
label(age) <- "Age"
sex <- factor(sample(c('male','female'), n, TRUE))
cens <- 15*runif(n)
h <- .02*exp(.04*(age-50)+.8*(sex=='female'))
dt <- -log(runif(n))/h
label(dt) <- 'Follow-up Time'
e <- ifelse(dt <= cens,1,0)
dt <- pmin(dt, cens)
units(dt) <- 'Year'
dd <- datadist(age, sex)
options(datadist='dd')
S <- Surv(dt,e)
tte<-data.frame(dt,e,age,sex)
############male group KM curve with bands#############
f <- survfit(Surv(dt,e)~1, data=tte,subset=sex=='male')
survplot(f,conf="bands", conf.int=0.95)
########notice no confidence band created#############
############female group KM curve with bands#############
g <- survfit(Surv(dt,e)~1, data=tte,subset=sex!='male')
survplot(g,conf="bands", conf.int=0.95,col=3, add=T)
 
Best regards, 
Hong
  		 	   		  
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