[R] cumulative incidence plot vs survival plot

[array chip]

Hi David,

Thanks for responding, and plain text ...(didn't realized I was in rich text).

The endpoint is disease recurrence, I was producing a regular KM plot of 
recurrence-free probability. Then someone recommend using cumulative incidence 
is preferred because death was censored in the dataset. I did a little googling, 
I found CI was used often in the context of competing risk. I am totally new to 
competing risk and trying to understand what competing risk means and why CI is 
preferred than KM survival in this context. If you could share your thoughts 
helping me to understand, greatly appreciated.

Searched archive, found people talking about cmprsk package for estimating and 
plotting CI. would that be the same as the code you suggested: plot(time, 
cumsum(dead))

Thanks very much!

John




________________________________
From: David Winsemius <dwinsemius at comcast.net>

Cc: r-help at r-project.org
Sent: Mon, June 27, 2011 1:45:35 PM
Subject: Re: [R] cumulative incidence plot vs survival plot


On Jun 27, 2011, at 4:31 PM, array chip wrote:

> Hi, I am wondering if anyone can explain to me if cumulative incidence (CI) is
> just "1 minus kaplan-Meier survival"?

First tell us what you think CI is defined as. I suspect it is not the same. The 

KM estimator is cumulative product of (alive-n(dead))/alive so is the product of 

interval survival probabilities. I doubt that your definition of CI has a 
similar denominator.


> Under what circumstance, you should use
> cumulative incidence vs KM survival? If the relationship is just CI =
> 1-survival, then what difference it makes to use one vs. the other?
> 
> And in R how I can draw a cumulative incidence plot.

plot(time, cumsum(dead)) ...?

> I know I can make a
> Kaplan-Meier survival plot using plot(survfit()), for example:
> 
> fit<-survfit(Surv(time,status)~group,data=data)
> plot(fit, col=1:2)
> 
> How to draw CI plot then?

As above. Specify what you are seeking.

There is a well-defined relationship between S(t) and the cumulative hazard. 
Maybe you should do a little study of those terms in texts regarding survival 
analysis.

> Thanks very much!
> 
> John
>     [[alternative HTML version deleted]]

Isn't it time you learned to post in plain text?

--
David Winsemius, MD
West Hartford, CT