Comparison of C statistics between 2 Cox proportional hazards models

[Nagi]

Hello everyone,

I am trying to compare c statistics between 2 models based on Cox proportional hazards model. I found out the way to calculate each c statistics of Cox models like below.

proc phreg data=nm concordance ;
model death_year*death(0) = sbp_m1;
run;

proc phreg data=nm concordance ;
model death_year*death(0) = sbp_m2;
run;

I want to compare 2 models: Y(death) = a + b･X(sbp_m1) and Y(death) = a' + b'･X'(sbp_m2)  using c statistics.

I think that there should be a statistics test which tests the null hypothesis; "c statistics (Model 1) - c statistics (Model 2) = 0". But I have no idea about the corresponding code.

Does anyone know it?

Any comments are welcome. 

Sincerely,

Nagi

[OsoGris]

I don't believe there is any code that can compare two c-statistics from two different models here. 

[Nagi]

Thank you for your reply!

So, is there no way to test a difference between c statistics? 

I have found p value between them in some papers. How did they calculate it?

Many thanks,

Nagi