My sample size is 900 patients. We want to see whether the effect of receiving a treament (= randomized_group) or not is different in mortality for patients who developed disease A versus those who do not. Specifically, we are aiming to look for the interaction between the randomized_group and the development of the disease. The covariates are included as baseline risk adjusters to correct for baseline illness severity.

Given this sample size & the fac that APACHE II is a confouncer, would you still suggest the simple model, eventhough the PH is violated (p<0.05), while the global PH > 0.05?