By the Kaiser Family Foundation – May 7, 2019
People on Medicare can choose coverage from either traditional Medicare or Medicare Advantage plans, typically trading off broad access to providers for potentially lower premiums and out-of-pocket costs. Beneficiaries who choose Medicare Advantage may differ from those in traditional Medicare in both measurable and unmeasurable ways, which may influence their use of services and spending. Yet, Medicare payments to Medicare Advantage plans per enrollee are based on average spending among beneficiaries in traditional Medicare.
This analysis looks at whether beneficiaries who choose to enroll in Medicare Advantage plans have lower spending, on average – before they enroll in Medicare Advantage plans – than similar people who remain in traditional Medicare. We compare average traditional Medicare spending and use of services in 2015 among beneficiaries who switched to Medicare Advantage plans in 2016 with those who remained in traditional Medicare that year, after adjusting for health risk. We adjust Medicare spending values for health conditions and other factors, with a model similar to the CMS HCC Risk Adjustment Model that is used to adjust payments to Medicare Advantage plans (see Methods).
Even after risk adjustment, the results indicate that beneficiaries who choose Medicare Advantage have lower Medicare spending – before they enroll in Medicare Advantage plans – than similar beneficiaries who remain in traditional Medicare, suggesting that basing payments to plans on the spending of those in traditional Medicare may systematically overestimate expected costs of Medicare Advantage enrollees.