[R] help drawing kaplan-meier plot starting from 0

[Frank Mattes]

Dear help news reader,

I'm trying to draw a Kaplan-Meier curve and would like to ask the news group for some help
Supposing I have study comapring two drugs, "A", and "B" and I recorde the time to get to the clinical endpoint (Time), in my case becommming virus free.

I have setup the following frame:
Time c Drug
1 5 1 A
2 7 1 B
3 2 1 A
4 10 1 B
5 6 1 A
6 8 1 B

"c" contains the coding if sucessful or not, but I think at the moment that is not important.
I did

fitstudy <- survfit(Surv(Time) ~ Drug, data=study) or
fitstudy <- fitstudy <- survfit(Surv(Time, c) ~ Drug, data=study)

and than

plot(fitstudy)

which gives me a Kaplan-Meier Curve, starting with 1. However I would like to the a plot
starting with "0" and than showing the increasing numbers of patients becomming "virus negative".

It would be great, if someone could point me in the right direction where I can find the answer.

Many thanks in advance
Frank

Frank Mattes, MD
Department of Virology
Royal Free and University Medical School
London

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