[R] HOW to use the survivalROC to get optimal cut-off values?

[petretta at unina.it]

I have the same problem of a prevous request

HOW to use the survivalROC (or another library in R) to get optimal  
cut-off values?

I want to use the time-dependent survivalROC package.according to  
the,reference material,it only gives a set of ordered cut-off values  
.eg.
--------------------------------------------------------------------------------

data(mayo)
str(mayo)
attach(mayo)
ROC.1=survivalROC(Stime=time,status=censor,marker=mayoscore4,predict.time=365,lambda=0.05)  
str(ROC.1)

plot(ROC.1$FP, ROC.1$TP, type="l", xlim=c(0,1), ylim=c(0,1),    
xlab=paste( "FP", "\n", "AUC = ",round(ROC.1$AUC,3)),    
ylab="TP",main="Mayoscore 4, Method = NNE \n Year = 1")   abline(0,1)

List of 6
$ cut.values : num [1:313] -Inf 4.58 4.9 4.93 4.93 ... *only 5 values

* $ TP          : num [1:313] 1 0.999 0.999 0.999 0.998 ...

  $ FP          : num [1:313] 1 0.997 0.993 0.99 0.987 ...
  $ predict.time: num 365
  $ Survival    : num 0.93

  $ AUC         : num 0.888

--------------------------------------------------------------------------------
so i dont know
how to use the survivalROC to get optimal cut-off values?(only 5 values)

Thank you very much!



Mario Petretta
Dipartimento di Medicina Clinica Scienze Cardiovascolari e Immunologiche
Facoltà di Medicina e Chirurgia
Università di Napoli Federico II
081 - 7462233