[R] How to stop Kaplan-Meier curve at a time point

[Göran Broström]

The functions 'age.window' and 'cal.window' in the package 'eha' are
designed to perform 'rectangular cuts' in the Lexis diagram. So, in your
case,

> require(eha)
> 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.

Göran Broström

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)
>
> -tgs
>
>
>
> 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
>>
>> Regards
>> Vinay
>>
>>          [[alternative HTML version deleted]]
>>
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>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at 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.
>