[R] cumulative incidence plot vs survival plot

[David Winsemius]

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