R help - Dec 2017 - permutation test for Cox proportional hazards regression model

I would like to perform a permutation test for Cox proportional hazards
regression model. I only find it for t-test and other tests (e.g. comparing
two medians).

Is there a way that I can perform a Cox PH model in R or SAS for the
LR-test?

I am doing the following

B <- 1000; LRtestx <- rep(NA,B);

Srv <- Surv(Time, Event);

for(j in 1:B){ LRtestx[j] <- cph(Srv~sample(x,length(x),replace=F))$stat[3]};

LRtest <- cph(Srv~x)$stat[3];

sum(LRtestx > LRtest)/B

Many thanks

Linda

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