Hi there, I'm trying to asses if is there an increased risk of virological failure in one year following only the first virological blip among a cohort of HIV patients.

For each participant i have:
Date of entry,
Date of exit (death for those who died)
Date of a virological blip.

Blip is a time depending variable. I would like to expand those patients who had a blip in three different times.
1) entry to time of blip
2) time of blip to one year later
3) one year after the blip to the end of follow-up

I would like to say to stata to cut the follow-up at the time of the blip only for those who have the blip. But they all have blip on different dates and i can't find a command to cut at the time of the blip event.

I hope it was clear.

Hope someone could help.



Pilade