National Coverage Determinations, or NCDs, are binding decisions made by the Centers for Medicare and Medicaid Services (CMS) that establish whether Medicare will pay for a particular medical item, service, procedure, or technology anywhere in the country. They exist to answer a deceptively simple question for roughly 67 million Medicare beneficiaries: is this treatment covered or not? The answer to that question shapes what care doctors offer, what patients can access, and how billions of federal dollars get spent each year. But the process behind these decisions, and the controversies they generate, is far more complex than a simple yes or no.
The “Reasonable and Necessary” Standard
Medicare’s statute says it will cover items and services that are “reasonable and necessary” for the diagnosis or treatment of illness or injury. That phrase is the legal backbone of every NCD. Interventions considered particularly controversial or expected to have a large impact on the Medicare program get funneled through the NCD process, where CMS examines whether the available evidence meets that standard.1PubMed. Factors Predicting Medicare National Coverage: An Empirical Analysis But here is the catch: what “reasonable and necessary” actually means has never been precisely defined. Congress left the phrase deliberately vague, and CMS has resisted locking in a rigid definition over the decades.
In practice, this ambiguity gives CMS significant discretion. The agency weighs clinical evidence, sometimes considers cost-effectiveness data, and makes a judgment call. For treatments where evidence is strong and risks are low, the process can be relatively straightforward. For expensive new therapies where the clinical data is still emerging, the determination can become a flashpoint among patient advocates, manufacturers, physicians, and budget-conscious policymakers who each have very different ideas about what “reasonable” should mean.
What Triggers an NCD in the First Place
CMS does not review every medical service through the NCD process. In fact, NCDs cover only a small fraction of what Medicare pays for. The vast majority of coverage questions are handled at the regional level by Medicare Administrative Contractors, the private companies that process Medicare claims across defined geographic areas. NCDs are reserved for big-ticket items, new technologies, and services where national consistency matters.2PubMed. Medicare is scrutinizing evidence more tightly for national coverage determinations
A request for an NCD can come from multiple directions. CMS itself can initiate one, or an outside party can submit a formal request. That outside party might be a medical device company hoping to secure guaranteed coverage, a professional medical society pushing for clarity, a patient advocacy group, or even an individual beneficiary. Once CMS accepts a request and opens a formal review, the clock starts ticking on a structured timeline with defined opportunities for public input and evidence review.
The volume of NCDs is surprisingly low. Between 1999 and 2007, CMS issued favorable decisions in about 60 percent of the cases it took on, though almost always with conditions attached to coverage rather than blanket approvals.3Health Affairs. Medicare’s national coverage decisions for technologies, 1999-2007 In more recent years, CMS has averaged only about three to four new NCDs per year, which underscores how selective the agency is about which questions it takes up at the national level.4JAMA Health Forum. Medicare’s New Pathway for Transitional Coverage for Emerging Technologies
How CMS Evaluates the Evidence
When CMS opens an NCD, the agency conducts its own review of the published medical literature. Sometimes it also commissions an external technology assessment, essentially an independent deep dive into the clinical evidence for the item or service under review. An analysis of NCDs finalized between 2005 and 2016 found that fewer than half included an external technology assessment, and only a small fraction involved a review by the Medicare Evidence Development and Coverage Advisory Committee, a panel of outside experts CMS can convene for especially complex questions.5PubMed Central. Evidence supporting FDA approval and CMS national coverage determinations for novel medical products, 2005 through 2016 That study also found that just two of the external assessments reviewed included cost-effectiveness information, which reflects how CMS has historically downplayed formal economic analysis in coverage decisions compared to agencies in other countries.
CMS has acknowledged that the evidence base for many technologies it reviews is thin. The agency has characterized the available evidence as “no better than fair” for most of the technologies considered during the 1999 to 2007 period.3Health Affairs. Medicare’s national coverage decisions for technologies, 1999-2007 This is a persistent tension in the NCD process: new technologies often arrive at Medicare’s doorstep with FDA approval in hand but without the kind of long-term outcomes data that CMS would ideally like to see before committing federal dollars to national coverage.
The Role of Public Comments
NCDs are not made in a back room. The process includes multiple formal opportunities for public comment, and CMS is required to consider and respond to every comment submitted. This is one area where patients, clinicians, and industry can directly influence a determination. CMS has said publicly that comments citing published clinical evidence are the most useful to its decision-making, and that comments referencing unpublished evidence are “less rigorous and therefore less useful.”6Health Affairs Scholar. Funding of evidence included within public comments submitted to inform Medicare national coverage determinations
That said, the public comment process has drawn scrutiny. The line between genuine public input and coordinated lobbying can be blurry. Device and pharmaceutical companies have strong financial incentives to flood the comment period with supportive evidence and testimonials. Advocacy groups, sometimes funded by industry, submit their own comments. This does not make the process illegitimate, but it means that readers should understand that public comments are one input among several, not a democratic vote on whether a treatment works.
NCDs Versus Local Coverage Decisions
If NCDs are relatively rare, how does Medicare decide on coverage for everything else? That is where Local Coverage Determinations, or LCDs, come in. The Medicare Administrative Contractors that process claims in each region can issue their own coverage policies for services not addressed by an NCD. These LCDs can and do vary from one part of the country to another, which means that a treatment covered in Florida might not be covered in Oregon if neither region is bound by a national determination.7PubMed Central. Local Versus National Medicare Coverage
This regional patchwork creates real consequences for patients and physicians. A doctor in one state might routinely order a diagnostic test that a doctor in another state avoids because the local contractor does not cover it. When CMS steps in with an NCD, it overrides all local policies on that item or service and establishes a single national rule. That is one of the primary justifications for NCDs: consistency. Without them, beneficiaries in different parts of the country can face meaningfully different access to the same treatment, depending purely on geography.
The flip side is that LCDs can sometimes be more flexible and responsive than the NCD process. A local contractor can issue or update an LCD relatively quickly, whereas the NCD process involves a structured timeline with public comment periods and formal evidence reviews. For treatments where the evidence is evolving rapidly, that speed can matter.
Coverage With Evidence Development
One of the more consequential innovations in the NCD process is a mechanism called Coverage with Evidence Development, or CED. It lets CMS say something unusual: “We are not sure this works well enough yet, but we will cover it if you agree to participate in research that helps us find out.” Under CED, Medicare provides coverage for an item or service through an NCD, but only on the condition that patients enroll in approved clinical studies designed to answer specific unanswered questions about the treatment.8PubMed. A Roadmap for Improving Medicare’s Application of Coverage With Evidence Development
The CED pathway is designed to bridge a real gap. Some treatments have enough early promise that denying coverage entirely seems unfair to patients who might benefit, but the clinical evidence has not yet reached the level CMS would normally require to call the treatment “reasonable and necessary.” CED threads that needle by providing coverage while simultaneously generating the data CMS needs to make a more definitive decision later.9PubMed. Assessing Medicare’s Coverage With Evidence Development Program
CED has been used for a range of technologies, from certain imaging procedures to novel drug therapies. Its use increased after the 2003 Medicare Modernization Act, which also imposed maximum review times on the NCD process and eliminated decisions that dragged on for more than a year.3Health Affairs. Medicare’s national coverage decisions for technologies, 1999-2007 But the program has also drawn criticism. Some researchers and patient advocates argue that requiring study participation as a condition of coverage creates a barrier to access, especially for patients who live far from major research centers or who cannot practically enroll in a trial due to age, frailty, or other health conditions.
The Alzheimer’s Drug Fight
No recent NCD has generated more controversy than the one for anti-amyloid monoclonal antibodies used to treat Alzheimer’s disease. When the FDA granted accelerated approval to aducanumab in 2021, the decision itself was contentious, with several members of the agency’s own advisory committee resigning in protest. CMS then had to decide whether Medicare would cover the drug and others like it.
In January 2022, CMS released a draft NCD stating it would use Coverage with Evidence Development to cover FDA-approved monoclonal antibodies for Alzheimer’s treatment. The condition was stark: coverage would only extend to patients participating in approved randomized controlled trials. By April 2022, CMS upheld that restriction in its final NCD, concluding that there was not sufficient evidence showing improved health outcomes to justify broader coverage under the “reasonable and necessary” standard.10PubMed Central. Analysis of the First Round of Public Comments for the National Coverage Determination for Monoclonal Antibodies in the Treatment of Alzheimer’s Disease
The decision exposed every fault line in the NCD process. Alzheimer’s advocacy groups argued that limiting coverage to clinical trial participants was cruel to millions of patients and families desperate for any treatment. Researchers pointed out that the FDA’s own advisory committee had questioned the clinical benefit of aducanumab. Budget analysts noted that unrestricted coverage could cost Medicare tens of billions of dollars for a drug with uncertain benefits. The Alzheimer’s NCD became a case study in what happens when the NCD process confronts a treatment where patient demand is enormous, the evidence is contested, and the financial stakes are staggering.
CMS later revised its approach as newer drugs in the class, such as lecanemab, produced stronger clinical trial results. The episode illustrates how NCDs are not static documents. They can be reconsidered and updated as the evidence base changes, though the process of reopening a determination carries its own political and procedural complexities.
Transitional Coverage for Emerging Technologies
CMS has recognized that the traditional NCD timeline can be too slow for certain breakthrough devices and technologies. In response, the agency created the Transitional Coverage for Emerging Technologies, or TCET, pathway. This newer mechanism is designed to accelerate coverage decisions for FDA-designated breakthrough devices, with the goal of finalizing a coverage decision within six months after a product receives FDA market authorization, provided that the manufacturer engaged early with CMS and collaborated effectively during the review process.4JAMA Health Forum. Medicare’s New Pathway for Transitional Coverage for Emerging Technologies
The TCET pathway is expected to roughly double or triple the number of NCDs CMS issues each year, from an average of three to four up to as many as nine. For device manufacturers, this is a significant change. Under the traditional process, a company could receive FDA clearance for an innovative product and then wait years for a favorable NCD, during which time Medicare reimbursement remained uncertain and adoption stalled. TCET is designed to compress that gap and give patients faster access to technologies that the FDA has already flagged as potentially transformative.
Whether TCET will deliver on that promise remains to be seen. The pathway is still relatively new, and questions remain about whether CMS has the internal capacity to handle higher NCD volumes without sacrificing the rigor of its evidence reviews. There is an inherent tension between speed and thoroughness, and the NCD process has historically tilted toward thoroughness even when that meant delays.
How NCDs Affect What Care You Actually Receive
For a Medicare beneficiary, an NCD can have immediate and tangible effects. A favorable NCD means your doctor can order a covered service with confidence that Medicare will pay for it, regardless of where you live. A non-coverage NCD means the treatment is not a Medicare benefit, and you would need to pay out of pocket or seek an alternative. A CED determination falls somewhere in between: coverage is available, but only if you can access and enroll in an approved clinical study.
The downstream effects extend beyond individual patients. When CMS issues an NCD for a new diagnostic technology, for example, it can reshape clinical practice across the country. A study examining Medicare’s NCD for next-generation sequencing in cancer care found that the national determination did not lead to an overall increase in the use of targeted therapies among beneficiaries with lung cancer, but it did reduce regional disparities that had existed when coverage was left to local contractors with different standards.11Cancer Research. Abstract 3688: Use of targeted therapies in lung cancer following medicare’s national coverage determination for next-generation sequencing In other words, the NCD did not necessarily expand total use, but it leveled the playing field geographically, which is exactly the consistency argument that proponents of NCDs emphasize.
Physicians pay close attention to NCDs as well. A non-coverage NCD can effectively end a treatment’s viability in the Medicare population, since most patients cannot afford to pay for expensive therapies out of pocket. Conversely, a favorable NCD with conditions can steer clinical practice in specific directions, such as requiring that a procedure only be performed at certain types of facilities or by physicians with particular qualifications.
Why NCDs Are Politically Charged
NCDs sit at the intersection of science, economics, and politics in a way that makes them inherently contentious. The agency is making rationing decisions whether it wants to use that word or not. Every non-coverage NCD is, functionally, a decision that Medicare beneficiaries should not have access to a particular treatment at taxpayer expense. Every favorable NCD opens the federal purse for a technology whose long-term costs and benefits may still be uncertain.
Industry pressures are real. Medical device and pharmaceutical companies invest heavily in securing favorable NCDs, both through the formal public comment process and through lobbying. Patient advocacy organizations, some of which receive industry funding, apply political pressure by framing non-coverage decisions as denying hope to vulnerable populations. Members of Congress occasionally weigh in, particularly when a determination affects a large constituency or a politically visible disease.
CMS has tried to insulate the process from political influence by grounding decisions in evidence review, but the ambiguity of the “reasonable and necessary” standard means the agency always has room for judgment. That discretion is simultaneously what makes the process flexible enough to handle novel situations and what makes it vulnerable to criticism that decisions are inconsistent or politically motivated. The Alzheimer’s drug controversy showed how quickly a coverage determination can become national news and how many competing interests converge on a single yes-or-no question about whether Medicare should pay.
The Tightening Evidence Bar
There is evidence that CMS has been raising the evidentiary bar for NCDs over time. An analysis published in Health Affairs found that the agency has been scrutinizing evidence more tightly, with a trend toward requiring stronger clinical data before issuing favorable national coverage decisions.2PubMed. Medicare is scrutinizing evidence more tightly for national coverage determinations This shift reflects broader trends in evidence-based medicine and health technology assessment, but it also creates friction with the innovation ecosystem. Manufacturers worry that a higher evidence bar delays patient access and discourages investment in technologies aimed at the Medicare population. Patients and advocacy groups worry about the same thing from the opposite direction.
The tension is not easily resolved. A lower evidence bar means Medicare might end up paying for treatments that turn out not to work, wasting limited resources and potentially exposing patients to harm. A higher evidence bar means some beneficial treatments reach patients more slowly, and the burden of generating additional evidence falls on manufacturers, researchers, and the patients who participate in trials. CED and TCET represent CMS’s attempts to find middle ground, but neither fully resolves the underlying trade-off between caution and speed.
For Medicare beneficiaries, this tightening standard means that FDA approval alone does not guarantee coverage. The FDA evaluates whether a product is safe and effective enough to be sold. CMS evaluates whether it is reasonable and necessary enough for Medicare to pay for it. Those are related but distinct questions, and the gap between them is where some of the most consequential battles in American health policy play out.