## Survival Analysis, issue finding pvalue for two groups analyzed

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# Survival Analysis, issue finding pvalue for two groups analyzed

This question is an extension of the same study I posted earlier involving transplant patients with Hodgekins lymphoma (HOD) and without Hodgekins lymphoma (NHL) and treatments allo or auto for these transplant patients. This is unidentifiable data and does not contain personal information.

I have two methods of coding for type of disease (HOD or NHL) and type of treatment (allo or auto) below:

data problem8_5;

input trt disease time status z1 z2;

*first coding method: each 4 group as separate dummy variables;

if trt=2 and disease=1 then NHLauto=1;

else NHLauto=0;

if trt=1 and disease=2 then HODallo=1;

else HODallo=0;

if trt=2 and disease=2 then HODauto=1;

else HODauto=0;

*2nd coding method: type of treatment, type of disease, and interaction;

if trt=2 then auto=1;

else auto=0;

if disease=2 then HOD=1;

else HOD=0;

datalines;

1 1 28 1 90 24

1 1 32 1 30 7

1 1 49 1 40 8

with the following models, respectively:

proc phreg data=problem8_5;

class  NHLauto(ref='0') HODauto(ref='0') HODallo(ref='0')/param=ref;

model time*status(0)= HODallo NHLauto HODauto/ties=breslow;

run;

*and;

proc phreg data=problem8_5;

class HOD auto;

model time*status(0)= auto HOD auto*HOD/ties=breslow type3;

contrast 'HOD auto vs NHL auto' HOD 1 -1 auto 0 1;

run;

How would we go about finding the p-value of the test that the survival rates of HOD allo patients and NHL allo patients are the same? I successfully found the p-value of the test that the survival rates of HOD auto vs. NHL auto are the same in the second PHREG procedure with the CONTRAST statement, which came back as the correct p-value=0.31, but just switching 'auto 0 1' to 'auto 1 0' does not give me the correct p-value for the two allo groups (which should be p-value=0.007)

Thank you! I appreciate any help my way !