English to Romanian Medical Medical (general) clinical trial

Context:
Any of the following events may be considered sufficient reason to discontinue subject participation in the study at the discretion of the Investigator or the sponsor. ...
- Lost to follow-up or inability to remain under medical observation during the entire duration of the study.

Am găsit definiţia:
Loss to follow-up
Loss of contact with some participants, so that researchers cannot complete data collection as planned. Loss to follow-up is a common cause of missing data, especially in long-term studies.
rctbank.ucsf.edu/BaT/html-files/glossary.html

Am găsit pe proz traducerea în franceză "perdu de vue". Cum am putea să traducem în română? Pacienţi cu care s-a pierdut contactul?
Mulţumesc anticipat.