I have built a Cox-regression model for 6 month mortality. When I created the original Kaplan–Meier curve, grouped by my variable of interest (hospital-acquired infection, Present vs Absent) the lines crossed – suggesting non-proportionality if used in a Cox regression model [subsequently confirmed via Schoenfeld residuals).
Therefore, I created a stratified Cox-regression model (adjusted for age):
coxph(Surv(Time, Status) ~ age + strata(HAI), data = survival)
The resultant summary of the above function, provides only co-efficients for age.
However, the co-efficient (and hence hazard ratio) I am interested in is for the stratified variable.
I appreciate stratification gives different baseline hazard ratios, but is there a way to generate a given HR for HAI?