The ACA created a capitated payment system for medicare that providers can opt into. I'm not sure what evidence you're looking for other than the definition of capitation is "fee per patient" as opposed to "fee for service." Some states like California also have capitated plans on from private companies. https://www.cms.gov/Medicare-Medicaid-Coordination/Medicare-...

Here's one for you: https://innovation.cms.gov/innovation-models/bundled-payment...

Quality of care provisions in Medicare/Medicaid/ACA all help to shift shift costs to the practitioner if care is poor or has bad outcomes.