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??
Solved – SPSS cox proportional hazard model adjusting for age
cox-modelregressionspss
Best Answer
The results you have posted represent the unadjusted and adjusted results. For group effect, one cannot create a hazard ratio for each group independently. Each group must reference the reference group in order to create a hazard ratio. The presence of age adjusts for all other covariates in the model, which includes groups. Each group’s hazard ratio is its effect referenced to group 5. With age in the model, each group’s hazard ratio is its adjusted hazard ratio relative to group 5. One could choose a different reference group to referencing if group 5 is not of interest or meaningful.