Except any department in any hospital or insurer that welcomes you to do research can make that de-identified data available to you with a simple contract.
How do you think college freshmen get in the door to work on research with physicians?
No, it’s not public, but it’s trivially accessible.
But I did. No, I use the word “trivial” knowingly.
The data for insurers is in the form of Billings (which come with Diagnosis codes!), which follows a federally-standardized format (check out the Medicare website) and you can get a sample of 5% of Medicare subscribers’ data off the Medicare site without any hoops to jump through.
I want to say, “if you actually know what to do with it, PM me and we can talk details,” but the fact that you don’t already know about this sort of low-hanging fruit suggests you’re from outside the hc sector looking in.