Once upon a time, 2008, the FED worked on drug abuse and settled cases against Big Pharma. ProPublica was / has a respository of many of those investigations. Sadly, it seems that that and other investigations of fraud into Medicare have been dropped by the previous administration. sigh.

Interestingly, one hospital in OK dropped their Medicare Advantage Plan, as it was too onerous and the hospital was loosing money. https://www.beckerspayer.com/contracting/oklahoma-hospital-terminates-medicare-advantage-contracts-amid-financial-challenges.html