In clinical trials companies only get access to patients' medical history by looking at it wherever it's stored (hospital, doctor's office). It can not be "taken home" or downloaded or whatever, for confidentially reasons. Similarly, if you work in a trial you can not have any direct contact with patients.
A trial involves administering a substance and then recording its efficacy by examining certain parameters (lab results, images, a questionnaire etc). Someone from the pharma company has to look at these results and then check the patient medical data to make sure there's no unrelated conditions that could have influenced that data (this was my job for a few years).
The company will have lab results with numbers instead of names and in a blind study, the treatment they received will be unknown to the company until it's "unblinded" at the end of the trial, which is usually done by an external company.
A trial involves administering a substance and then recording its efficacy by examining certain parameters (lab results, images, a questionnaire etc). Someone from the pharma company has to look at these results and then check the patient medical data to make sure there's no unrelated conditions that could have influenced that data (this was my job for a few years).
The company will have lab results with numbers instead of names and in a blind study, the treatment they received will be unknown to the company until it's "unblinded" at the end of the trial, which is usually done by an external company.