Multivariate Cox proportional hazards regression

[Abimal_Zippi]

Hello!

In the multivariate cox model, the Hazard ratio estimate for one of the explanatory variables rather increased in the adjusted model compared to the univariate Hazard ratio estimate. Can any one suggest a method to identify the interacting variable/s responsible for the higher HR in the adjusted model?

[Reeza]

Did you include and test interaction terms in your model?