Hi,
I'm sure this should be simple but I can't figure it out! I want to get the
median survival calculated by the survfit function and use the value rather
than just be able to print it. Something like this:
library(survival)
data(lung)
lung.byPS = survfit(Surv (time, status) ~ ph.ecog, data=lung)
# lung.byPS
Call: survfit(formula = Surv(time, status) ~ ph.ecog, data = lung)
1 observation deleted due to missingness
n events median 0.95LCL 0.95UCL
ph.ecog=0 63 37 394 348 574
ph.ecog=1 113 82 306 268 429
ph.ecog=2 50 44 199 156 288
ph.ecog=3 1 1 118 Inf Inf
What I want is to be able to call the median using something like:
lung.byPS$median[ph.ecog=0]
so that I can add it to a plot like this:
plot (lung.byPS,
conf.int=F,
lty=1:4,
)
abline(h=0.5, lty=5)
abline(v=lung.byPS$median[ph.ecog=1])
abline(v=lung.byPS$median[ph.ecog=2])
Anyone got any easy solutions? Its fairly normal to plot across and down to
show medians on survival curves... so I'm sure it must be possible to automate.
Ta
Calum
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