[R] How to stop Kaplan-Meier curve at a time point
gb at stat.umu.se
Tue Nov 26 12:34:57 CET 2013
The functions 'age.window' and 'cal.window' in the package 'eha' are
designed to perform 'rectangular cuts' in the Lexis diagram. So, in your
> dat <- data.frame(enter = rep(0, length(Survival_days), exit =
Survival_days, event = Outcome)
> dat.1 <- age.window(dat, c(0, 2190))
and 'dat.1' is your right-censored data set.
On 11/21/2013 07:36 AM, Thomas Stewart wrote:
> One solution is to format the data as if the follow-up period ended on day
> 2190. For example,
> TTT <- Survival_days
> DDD <- Outcome
> DDD[ TTT>2190 ] <- 0
> TTT[ TTT>2190 ] <- 2190
> survfit(Surv(TTT, DDD) ~ Gender)
> On Wed, Nov 20, 2013 at 3:01 PM, Dr.Vinay Pitchika
> <dr.vinay.muc at gmail.com>wrote:
>> Hello R users
>> I have a question with Kaplan-Meier Curve with respect to my research. We
>> have done a retrospective study on fillings in the tooth and their survival
>> in relation to the many influencing factors. We had a long follow-up time
>> (upto 8yrs for some variables). However, we decided to stop the analysis at
>> the 6year follow up time, so that we can have uniform follow-up time for
>> all the variables.
>> I did play a bit with the formula and tried to stop the Kaplan-Meier curve
>> at my desired time (2190days)or roughly 6 years. However, my question is I
>> want to find the significance (log rank test) at this time point between
>> the two curves; because I am not able to find a way to stop the survfit at
>> this time point with my knowledge. Below is the code I used.
>> Gender2<-survfit(Surv(Survival_days, Outcome)~Gender)
>> plot (Gender2, xmax=2190, mark.time=FALSE, col=c(1:2), xlab="Survival time
>> (Days)", ylab="Survival probability", main="Gender") # mark.time=FALSE will
>> remove the censoring lines in the graph. If censoring lines are needed,
>> then remove the mark.time section in the formula.
>> legend("topright",c("Females", "Males"), col=(1:2), lwd=0.5)
>> Am sure, the code in the first line has to be modified. Please help me with
>> this and I will be very thankful to you.
>> Thanks in advance
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