Private insurance actually started a lot of these initiatives. If you're a physician with a busy practice, at the end of the month, you'll get a check from all of the big insurance companies detailing how much they're paying you.
It doesn't read, "You saw 100 patients at $100/patient, here's $10,000."
It's more like, "You saw 100 patients, here's your per-patient fee of $50. You prescribed 87% generic medicines, which for a doctor with your patient population in your area underperforms by 2 percentage points, this equates to a $1,400 bonus -- if you prescribed 91% generics, this bonus would be $2,500. Only one of your patients required an off-formulary medcine, your bonus here is $500."
There are a lot of competing interests right now, the formerly independent doctor groups are all merging together, insurance companies are merging, hospitals are merging. There's also a big push for risk-based reimbursement:
http://www.mckesson.com/bps/blog/riding-the-shifting-landsca...