Oooh. This is just begging for a privacy firestorm when someone de-anonymizes the data, which I'm guessing won't be super hard given the kind of medical features they'd need to provide to make this task useful.
You can also look for specific people in there if you have certain kinds of prior information about them: For example, Aravind Narayanan was able to de-anonymize some part of the Netflix set [http://arxiv.org/abs/cs/0610105]. Maybe that won't translate to this data.