Multiple complex diagnoses tied to Medicare Advantage exits

Clinical takeaway: Patients who add complex conditions, especially dementia, often change Medicare coverage within the year. Verify current coverage before ordering referrals, imaging, or authorizations that assume the same network will still apply.

The year after a new complex diagnosis is typically when care interactions intensify. Referrals multiply, imaging and medications get added, and prior authorization becomes a routine part of the visit. It is also, for a substantial share of older adults, the year their coverage changes. The coincidence of these can quietly undermine the ability of the patient to receive affordable, timely care. 

Medicare Advantage (MA), the privately managed side of the program, accounted for 54% of total Medicare enrollment in 2025. The tradeoff is familiar to anyone who has fought a denial: out-of-pocket maximums, integrated drug coverage, and supplemental benefits on one side, prior authorization and limited networks on the other. That bargain reads differently once a patient's needs rise, but the exit is not equally available. 

Most states do not require guaranteed issue and community rating for Medigap, the supplemental insurance that covers what traditional Medicare leaves out, so beneficiaries who leave MA may be denied a policy or priced out of one. A difference-in-differences cohort study followed more than one million MA beneficiaries who were free of complex conditions at baseline, comparing those who developed a new complex condition with those who developed none. 

Developing any new complex condition was associated with a 3.3 percentage point increase in leaving the prior year's plan, and almost all of that movement was exit to traditional Medicare rather than a switch to another MA plan. The effect grew with each added condition, from 1.4 points for one to 12.8 points for four or more. Raw rates show the same pattern: by 2020, 37.3% of beneficiaries with four or more new conditions had left their plan, compared with 17.6% of those who developed none. 

Direction of movement also shifted with burden. Beneficiaries with a single new condition were the only group more likely to shop within MA; those with four or more were less likely to switch plans than beneficiaries who stayed healthy, meaning the sickest patients were leaving rather than comparison-shopping. Alzheimer disease and related disorders carried the largest effect of any single condition. 

State policy shaped whether an exit was even possible. In the four states with both guaranteed issue and community rating Medigap, beneficiaries with new complex conditions were 1.5 points more likely to move to traditional Medicare than similar beneficiaries elsewhere, and that gap widened as conditions accumulated. Enrollees in HMOs moved the other way, shopping within MA rather than leaving it. 

Researchers used Medicare enrollment and claims data from 2016 through 2021, identifying beneficiaries enrolled in MA for all of 2016 with no complex condition through 2018. Complex conditions were acute myocardial infarction, Alzheimer disease and related disorders, atrial fibrillation, chronic kidney disease, COPD, depression, congestive heart failure, and stroke. Disenrollment was measured annually and only among those enrolled in MA the prior year. 

The practical problem is that a coverage change is invisible until something breaks: a referral bounces, an authorization restarts, a specialist falls out of network. Asking about coverage at the first follow-ups after a complex diagnosis catches that early. It also sets up an honest conversation for patients who want out of MA, since in most states leaving means facing medical underwriting for a Medigap policy. 

Source: Meiselbach MK, et al. (2026 Aug 21) JAMA Health Forum. Medicare Advantage Beneficiary Enrollment Decisions Following New Complex Conditions