Mostly in preparation for sharing the study data with others (E.G. Publishing, outside data processing). It's just good hygiene to have the non-sensitive data

Mostly in preparation for sharing the study data with others (E.G. Publishing, outside data processing). It's just good hygiene to have the non-sensitive data isolated from the sensitive stuff. Identifying information belongs under lock and key, or at least forcing a user to authenticate again (even if by literal physical key-fob/ID card) (and should for the hospital too). Answers to questions which can't be classified as the above can be associated with a fully synthetic ID that works as a pointer to the above. That makes them less sensitive (but still important to keep secure: E.G. they could be in the office which is always locked when un-occupied and don't have to be stored in the safe). Practicing this discipline also makes it less likely for researchers and writers to inadvertently leak patient data. I'm actually shocked at how often hospitals / clinics / etc don't practice similar division of data by storage requirement.