# SPSS cox proportional hazard model adjusting for age

I'm using SPSS to run cox proportional hazard model. I've five different groups and I need unadjusted and adjusted (for age) HR for all of them separately. My first group is a reference group. I've added this 'group' variable as covariate in the covariate box indicating which one is reference, but when I add age in the same box (to adjust for), it gives me single adjusted HR for age for all the groups. How can I get age adjusted HRs, each for one group, separately? Age is a continuous variable, should I change its category??

• Are your groups coded with 'dummy' variables? Showing the output may help illuminate the problem. If age and group are in the model at the same time, then group (and age) effect will be adjusted for one another. Jan 21, 2019 at 15:35
• @ToddD: I have numbered my groups as cluster 1 to 5. Age is a continuous variable. I've added the output screenshot above. While the HRs looks a bit different from the unadjusted model, I'm not sure adding 'age' in the same model I can call these HR values in the Table as being adjusted for age, can I? Jan 21, 2019 at 16:03

You will, however, get 4 additional regression coefficients related to age, interaction coefficients of age with each of the non-reference groups. The ways these are presented can differ among software packages. With the R coxph() function at default settings, the main coefficient for age would be its relationship to outcome in the reference group, and the other 4 age-related coefficients would be the group-associated differences from that reference relationship. I'm not sure how SPSS displays its results in such a situation.