How do I use proc phreg for multiple testing of a ref. population to 2 control population.

[MrTensa]

Hi everyone,
I need some help using proc phreg to test a population to 2 control populations for my adjusted COX model.
I have a dataset made of 3 populations, which are matched with each other using greedy matching macro.

Case=1 refers to population A, which I have matched in a ratio of 1:4 to the background population(case=0, count) and population B(case=2, count_s) in a ratio of 1:1.

The problem is that I am currently testing population A separately with the other population; so 2 populations at a time. I wanna to know how to test population A with both the background population and population B at the same time.

The code I am currently using;

Proc phreg data=dataset;
class case (Ref='0'); 
Model time_to_event * event_end (2)= variables variables variables variables /rl;
strata count;
run;

Proc phreg data=dataset;
class case (Ref='2'); 
Model time_to_event * event_end (2)= variables variables variables variables /rl;
strata count_s;
run;

Thanks for the help! 🙂

[SteveDenham]

See the third example in the PROC PHREG documentation - "Modeling with Categorical Predictors."  That points out the use of the CONTRAST statement to get comparisons of interest.

SteveDenham