# Analyzing survival: meaningful to report estimates for different time periods with Cox and AFT?

I am trying to figure out the following. Could you please comment on this?

Goal is to compare survival between two groups. Let's assume we have data with one-year follow up and have a simple model for getting age-adjusted estimates:

time | status ~ group + age


Is it reasonable to run models with different follow-up lengths? E.g. 1, 2, 6 and 12 months? By reasonable, I mean does it give some extra or valuable information?

My understanding is as follows:

If this is a Cox model

If the assumption of proportional hazards is met with all follow-ups, there is no point run models with different follow-ups due to the PH assumption. For example, one group always has a constantly higher/lower hazard ratio.

If this is an Accelerated Failure Time (AFT) model

If the proportional hazards assumption is not met, I would use AFT. Is it now reasonable to run models with different follow-ups? For example, group A and B may have similar 1- and 3-month survival but patients in group B die more likely after the 3rd month.