When was the last time your team won an appeal on a clinical validation downgrade? If you have to stop and think about it, you are not alone.
Payer behavior has made this harder than it used to be. Clinical validation audits are driving a marked rise in Diagnosis-Related Group (DRG) downgrades, forcing hospitals to defend diagnoses that, for years, were accepted on the strength of a physician’s documentation alone. As audits grow more frequent and the criteria keep shifting, traditional coding and documentation practices no longer secure full reimbursement.
The exposure is real. In 2025, hospitals spent nearly $18 billion overturning claims denials, according to the American Hospital Association. Against margins this thin, even a modest rate of downgrades adds up quickly.
But the teams that protect the most revenue don’t just win more appeals. They reduce their exposure earlier, before claims are submitted and contracts are signed.
Understanding the difference between DRG and clinical validation audits
Traditional DRG validation audits confirm that diagnoses and procedures are coded and sequenced correctly, in line with the official ICD-10-CM guidelines. In that review, a provider’s statement that a condition exists is generally enough for code assignment, because the focus is on applying coding rules rather than second-guessing the clinical reasoning behind the diagnosis.
Clinical validation audits work differently. Since their introduction in the 2011 Recovery Audit Contractor (RAC) Statement of Work, payers have applied a separate standard, testing whether objective evidence in the medical record, such as laboratory results, imaging, clinical signs, and treatment response, supports the diagnosis itself. Here the clinician’s opinion, however expert, is not the deciding factor. A correctly coded diagnosis can still be disputed if the payer decides the record does not support it.
The practical effect is significant. A case coded correctly as sepsis can be downgraded to a less severe infection, or removed entirely, if the payer judges the objective evidence insufficient.
What’s driving the increase
The rise in downgrades is not random. Payers are deploying machine learning and audit tools that flag far more claims for review, and the diagnoses that carry the highest reimbursement, such as sepsis, acute respiratory failure, acute kidney injury, and severe malnutrition, are the most frequent targets.
Adding to the friction, payers often apply different clinical criteria than the treating physicians. For example, clinicians have largely moved to Sepsis-3 definitions, yet many payers still review claims against Sepsis-2. Neither the ICD-10-CM Official Guidelines nor AHA Coding Clinic requires Sepsis-3 for diagnosis coding, so a payer imposing that threshold is applying a standard that exceeds CMS coding guidance. That is a contestable overreach, not a legitimate basis for denial, but only if your team recognizes it as one.
There’s a deeper, structural problem. Payers, clinicians, and federal programs often apply different criteria to the same DRG, and most contracts say nothing about how downgrades will be handled, so hospitals start at a disadvantage before any appeal is filed. Payers can also change terms with little notice, since many contracts let an amendment take effect without the provider’s signature. Payers can introduce new criteria or downgrade procedures without warning, in part because many contracts contain language stating that “the signature of Provider will not be required in order for the amendment to take effect.”
Get the terms right before a dispute
The best defense against a downgrade is written into the contract long before a claim is audited. When negotiating or renewing payer agreements, several provisions are worth asking for.
- Defined, published criteria. Require payers to use recognized, published clinical definitions rather than internal or undisclosed criteria when questioning a diagnosis.
- Physician-level review. Mandate that only a qualified physician, not a coder or an algorithm, can overturn a treating physician’s documented diagnosis.
- Peer-to-peer rights. Guarantee your physician a direct conversation with the payer’s reviewing physician before a downgrade is finalized.
- Advance notice of changes. Require written notice before any change to clinical criteria or downgrade procedures takes effect.
- Audit limits. Set explicit caps: a percentage limit (e.g., no more than 5% of DRG claims reviewed per quarter), a fixed volume limit, a defined lookback window such as 12 months from date of service, and restrictions on extrapolating findings from a small sample across a broader population of claims.
Regulation can reinforce these positions. Under CMS-4208-F, effective January 1, 2026, once a Medicare Advantage plan approves an inpatient admission, it generally cannot reverse that approval based on information gathered after the fact, absent fraud or obvious error. Hospitals unaware of that protection may be conceding reversals they no longer have to accept.
Close the gaps you cannot negotiate away
Contract terms reduce exposure, but they do not eliminate it. The rest of the defense is operational.
- Validate high-risk DRGs before billing. A pre-bill clinical validation review on those high-risk DRGs catches weak documentation while it can still be fixed.
- Make CDI concurrent, not retrospective. Documentation gaps are far easier to close during the encounter than after discharge, and a concurrent query is far more effective than a post-discharge appeal.
- Monitor trends by payer and DRG. Track how often downgrades occur and which payers and diagnoses drive them. A repeated pattern from one payer on one DRG is a signal of systemic audit activity, and for public payers it can precede extrapolated recoupment across a wider set of claims.
- Measure what overturns denials. Analyze which appeal strategies succeed and apply those lessons across the organization. In Medicare Advantage, roughly 57% of denied claims are ultimately overturned, a sign that a large share of denials are reversible when challenged. The revenue is recoverable, if your process is built to capture it.
Moving forward
The teams that protect the most revenue treat audits as moving targets and defend accordingly, starting with the contract, reinforced at the point of care, and backed by the discipline to spot patterns early. Handled that way, DRG downgrades stop being an unpredictable drain and become a manageable, measurable part of revenue integrity. There’s a clinical payoff, too. When you run the revenue side this way, physicians and coding teams spend less time defending documentation after the fact and more time on the patients in front of them. Few teams can sustain this alone, and no contract enforces itself, so the strongest defenses pair disciplined internal work with the right outside expertise.
And the next time someone asks when your team last won a clinical validation appeal, you’ll have an answer ready.
About Adele Frias
Adele Frias is Vice President of Specialty Revenue Cycle Solutions, EnableComp.
