Experimental and investigational denials are some of the most frustrating claim denials providers face. A procedure may be FDA approved, medically necessary, and even authorized, yet still denied as “experimental” or “non-covered.”
In this Q&A, Aspirion’s Rikki Ashkin, J.D., Senior Client Success Director, breaks down how these denials work, and how to respond effectively, with the aim of improving appeal success rates and reimbursement outcomes.
Q: What is an experimental or investigational denial?
Rikki Ashkin: This is actually a more nuanced question than it might seem. The American Medical Association (AMA) has never adopted a universal definition of what qualifies as experimental or investigational, which is a big reason these denials look so different depending on the payer or health plan.
At its core, though, an experimental or investigational denial happens when a payer determines that a procedure, treatment, medication, device, or lab test is not covered for the patient’s specific condition or intended use. You might see these show up on an EOB as “Experimental/Investigational,” “Non-Covered,” or “Not a Covered Benefit.”
Q: Why do some payers cover a treatment while others deny it, and can I use other payers’ approvals to strengthen an appeal?
Rikki Ashkin: It really comes down to the fact that every carrier builds its own coverage criteria. These are typically outlined in Clinical Policy Bulletins (CPBs) or Medical Coverage Guidelines (MCGs), which define what is medically necessary, which diagnoses qualify, and what documentation is required. So, one payer might approve IVIG therapy for a specific diagnosis while another denies the exact same service under its own guidelines.
The good news is that this inconsistency can actually work in your favor on appeal. If other major payers—like Medicare or large national commercial payers—cover the same service for similar indications, you can use a cross-payer consistency argument to make the case that the treatment is not truly experimental within the broader medical community.
Q: How are Medicare experimental denials different from commercial insurance denials?
Rikki Ashkin: Medicare operates under a very different framework. Coverage is governed by National Coverage Determinations (NCDs) and Local Coverage Determinations (LCDs), now often called Articles. NCDs apply nationwide, but LCDs and Articles vary by Medicare contractor region—so a procedure covered in one state may not be covered in another. It is also worth noting that Medicare Advantage plans are required to follow applicable Medicare coverage policies for Medicare beneficiaries, rather than applying commercial insurance guidelines.
Q: What should providers review first when handling an experimental denial?
Rikki Ashkin: The first thing I always recommend is identifying exactly what type of policy is driving the denial. Is it a commercial Clinical Policy Bulletin (CPB), a Medicare Local Coverage Determination (LCD), a National Coverage Determination (NCD), or something else?
From there, you need to dig into whether the denial is really about diagnosis coding, clinical documentation, medical necessity, or a benefit plan exclusion—because each of those requires a different approach. You cannot build an effective appeal until you know precisely what you are up against.
Q: What is the difference between a diagnosis denial and a clinical denial?
Rikki Ashkin: These are two very different situations. A diagnosis denial is usually a coding issue rather than a true medical necessity question. Many payer policies only cover certain services when specific diagnosis codes are billed alongside the procedure code—if that pairing is missing from the claim, it can automatically deny as experimental.
A clinical denial, on the other hand, is about the patient’s actual condition. The payer is evaluating the medical history, prior treatment failures, and whether it believes the treatment was truly necessary for that specific patient based on its own policy criteria.
Q: Can a service still deny as experimental even if authorization was approved?
Rikki Ashkin: Unfortunately, yes—and this catches a lot of providers off guard. Authorization approval does not guarantee payment. A payer can still deny the claim if the treatment is excluded under the patient’s benefit plan, or if the diagnosis that was authorized does not match what was ultimately billed. That is why it is so important to verify upfront exactly which CPT and diagnosis codes were included in the authorization.
Q: What information strengthens an appeal for an experimental denial?
Rikki Ashkin: A strong appeal tells the patient’s story clearly and directly addresses the payer’s own policy criteria. That means documenting the medical history, prior failed treatments, and the specific reasons this service was medically necessary. Whenever possible, get supporting documentation from the treating physician.
Beyond that, peer-reviewed literature, FDA approval information, National Institutes of Health (NIH) studies, and guidance from organizations like the American Medical Association (AMA), National Comprehensive Cancer Network (NCCN), or the National Cancer Institute can all go a long way in demonstrating that the treatment reflects accepted medical practice—not something experimental.
Q: Can FDA approval help overcome an experimental denial even if the payer policy excludes the service?
Rikki Ashkin: Yes, and it can be a powerful tool, especially when paired with medical literature and physician documentation. If the payer policy looks outdated or does not account for newer FDA-approved indications, you can argue that the payer is relying on clinical criteria that simply no longer reflect current medical practice. That is a compelling position to be in on appeal.
Q: What if the patient does not fully meet the payer’s policy criteria?
Rikki Ashkin: Not meeting every box on the payer’s checklist does not necessarily mean the appeal is a lost cause. In many cases, you can still challenge the denial by arguing that the policy itself is outdated or out of step with current medical evidence. When a payer’s Clinical Policy Bulletin (CPB) hasn’t kept pace with the latest evidence, citing newer research that demonstrates improved outcomes, including expanded indications, or documenting evolving standards of care can be powerful appeal strategies.
The goal is to demonstrate that the payer is working from outdated criteria while the clinical community has already moved on.
Q: What is “policy silence,” and why is it important?
Rikki Ashkin: Policy silence is when the payer’s Clinical Policy Bulletin (CPB) or Medical Coverage Guideline (MCG) simply does not address the service or indication at all—and it is an important distinction from an outdated policy. In those situations, the denial is not based on an explicit exclusion; it is based on the absence of coverage language.
That opens the door to a different kind of argument:
“The payer’s Clinical Policy Bulletin does not address this specific indication; therefore, the service cannot be classified as experimental solely due to policy omission.”
What that does is shift the entire argument away from defending against specific criteria and toward challenging whether the denial even has a valid basis to begin with.
Q: Should patients be involved in the appeal process?
Rikki Ashkin: Absolutely, and this is especially true for self-funded or employer-sponsored plans. Providers should notify patients promptly when a denial comes in and, if possible, request copies of the benefit plan documents. Patients may also need to sign authorization forms so that providers can pursue appeals, external reviews, or independent review organization (IRO) requests on their behalf. Getting patients engaged early can make a real difference.
Q: What is the most important takeaway about experimental denials?
Rikki Ashkin: The biggest thing I want providers to walk away with is that winning these appeals takes more than just checking boxes against a payer’s policy criteria. The most effective approach is layered. Start by confirming that you have the correct policy version and that it actually applies to the specific plan and date of service. Then identify exactly what type of denial you are dealing with—whether it is truly clinical, a benefit exclusion, or a coding issue—because each one calls for a different strategy.
From there, look for opportunities to challenge policy gaps or silence rather than just defending against explicit criteria. Cross-payer consistency and FDA approval can strengthen your position significantly. Sometimes the strongest outcomes come not just from proving medical necessity, but from showing that the payer’s own policy framework is outdated, incomplete, or simply misapplied.
Physician documentation is also central, particularly when it clearly ties medical necessity to the patient’s specific clinical situation. And when internal appeals have run their course, do not overlook escalation pathways like external review or contractual remedies.
Experimental and investigational denials do not have to be the final word. With the right strategy and AI-powered support, many are winnable. Reach out today to learn how Aspirion can help your organization recover its earned revenue.
