I'm the lead data scientist for a company that collects data. I have approximately 90% of medical claims filed at all hospitals, clinics, general practitioners, etc.
I anonymize the data into zip code, state, age range, etc, and create diagnosis and procedure groups. Then, I sell that data to company x who wants to bring a new drug or medical device to market. I tell them what region has the highest diagnosis or procedure rates, so they can send their sales reps to places where their drug is actually useful, reducing their cost, and thus the cost of the drug.
For the record, there's about 6 billion records a year. With all sorts of information on them. And all sorts of HIPAA requirements to abide by.
And it's the sole reason I refuse to go to the doctor for anything beyond catastrophic emergencies. Which is not compoletely uncommon for me.