Hello:

I would like to obtain probability of an event for one single patient as a
function of time (from survfit.coxph) object, as I want to find what is the
probability of an event say at 1 month and what is the probability of an
event at 80 months and compare. So I tried the following but it fails
miserably. I looked at some old posts but could not figure out the solution.
Here's what I did where for one single patient, the answer is "NULL". Could
anyone help me with the problem?

R.app GUI 1.34 (5589 Leopard build 32-bit)

> library(glmpath)
*> dataall <- list(x=lung.data$x[1:130,], time=lung.data$time[1:130],
status=lung.data$status[1:130])*
*

> fit.a <- coxpath(dataall)

> testall <- list(x=lung.data$x[131:137,], time=lung.data$time[131:137],
status=lung.data$status[131:137])

> testpred <- predict(fit.a, testall, s=0.99, type='coxph',
mode='lambda.fraction')


> testpred

Call:

coxph(formula = Surv(time, status) ~ x, method = object$method)

          coef exp(coef) se(coef)      z    p

karno -0.00756     0.992   0.0364 -0.208 0.84

Likelihood ratio test=0.89  on 1 df, p=0.344  n= 7

> newd1 <- list(testall$x[1,])

> survtest <- survfit(testpred,newdata=newd1,individual=T)

> survtest

Call: survfit(formula = testpred, newdata = newd1, individual = T)


records   n.max n.start  events  median 0.95LCL 0.95UCL

      7       0       0       0       0       0       0

> summary(survtest)

Call: survfit(formula = testpred, newdata = newd1, individual = T)

      time n.risk n.event survival std.err lower 95% CI upper 95% CI

  > survtest$survival



NULL


*

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