RMS Parametric Survival Models

How do you deal with the challenges of the proportional hazards assumption that Hernan raised? The HR is a conditional-on-survival quantity that selects on the outcome over time, by time t , the surviving treated and control populations are no longer comparable even under baseline randomization. (b) The HR depends on follow-up duration; the same trial reported at 1 year, 3 years, and 5 years will produce different HRs even when the underlying biological effect is unchanged. Thank you.