What is Medicare coverage with evidence development?

What it is

Coverage with evidence development - usually written as "CED" - is one of the ways Medicare can decide to pay for a treatment. It is not the same as ordinary Medicare coverage. Under CED, Medicare agrees to cover the treatment on the explicit condition that clinical data about how the treatment is used, and how the patient does, is collected and reported back to CMS.

Put simply: Medicare is saying yes, we will pay for this, and at the same time, we want to learn more about how it actually performs outside of clinical trials.

Why CMS uses it

CMS uses CED when a treatment has regulatory approval but important questions remain about real-world performance - questions that the original trial data cannot fully answer. These questions might be about safety, durability of effect, which subgroups benefit most, or how the treatment performs in clinical practice compared to the trial setting.

Anti-amyloid antibodies for early Alzheimer's - lecanemab and donanemab - are the highest-profile current example of a CED coverage decision. CMS issued a National Coverage Determination in 2023 that structured anti-amyloid coverage through the CED framework, with patient enrollment in a CMS-approved registry as the mechanism for collecting the required evidence.

What CED means in practice

For the patient, the practical effect is that coverage exists, but it is tied to being cared for at a participating site and to having certain information about their treatment reported to a registry. The clinical care is delivered normally; the registry layer runs alongside it.

For the prescribing practice, CED is a meaningful operational commitment. The practice has to enrol in an approved registry, train staff to capture the required data fields, and submit data on a defined schedule. For anti-amyloid therapy, this has been one of the practical reasons that prescribing has concentrated at larger practices and academic centers with research operations already in place. The downstream effects are covered in our Signal on Medicare's CED decision.

What data gets collected

The specific fields CMS requires are laid out in the registry documentation and evolve over time, but in broad terms they cover:

• Patient demographics and baseline clinical characteristics.
• Diagnostic biomarker data - amyloid PET, CSF, or plasma test results and APOE genotype.
• Treatment course - dose, infusion dates, adjustments, and pauses.
• Clinical and safety outcomes - cognitive and functional measures, adverse events (especially amyloid-related imaging abnormalities).

The goal is a real-world dataset that, aggregated across many participating sites, can inform future coverage refinements.

How long CED runs

CED is not permanent. It is a coverage structure designed to be revisited as evidence accumulates. Medicare can, in principle, modify or end the CED framework and transition the treatment to ordinary coverage - or the reverse, if accumulated evidence warrants. For anti-amyloid, the registry data being collected under the current NCD is expected to feed directly into how Medicare's future coverage decisions are shaped. The broader shift toward real-world data as the binding evidence in Alzheimer's is covered in our Insight on real-world data becoming the binding signal.

Not unique to Alzheimer's

CED has been used for a range of prior coverage decisions - for implantable cardiac devices, some oncology therapies, transcatheter aortic valve replacement, and others. The anti-amyloid CED is one of the most operationally demanding applications of the mechanism to date, because it involves a large eligible population and a new drug class with nuanced safety monitoring.

What this means in practice

If the question is practical - "is this patient's treatment covered?" - CED-based coverage exists and has been functioning since 2023. The registry requirement runs behind the scenes at the practice level; the patient experience during infusions and monitoring is not meaningfully different from any other covered treatment. Payment for the treatment proceeds normally as long as the registry reporting is happening.

If the question is strategic - "how should this framework be read?" - CED represents a shift in how Medicare approaches coverage for expensive, class-defining therapies with evolving evidence bases. It is likely to be applied to other emerging neurodegenerative treatments as they arrive.

This page is a plain-language primer. It is not medical or benefits advice.