Who Actually Appeals a Medical Claim Denial in America?

HealthCare.gov insurers denied about 85 million in-network claims in 2024; fewer than one percent of patients fought back, and what the fighters found

The letter is dated February 6, 2025. Nathan Kirkland, a liver cancer patient in his forties, opened it and read his insurer’s verdict on the transplant his surgeons had recommended. “Medical studies do not show that this surgery will improve your short- or long-term health,” the Anthem letter stated. Kirkland’s out-of-pocket costs by then totaled about 250,000 dollars. He shared the letter with Medscape Medical News and described the moment in five words: “It was a gut punch. This can’t be real.”

The letter had a second problem, visible only later. It named his cancer as hilar primary sclerosing cholangiocarcinoma, a bile-duct cancer that develops outside the liver. Kirkland had intrahepatic cholangiocarcinoma. A medical director reviewer had picked the wrong term from a drop-down menu, his appeals team later established, in a denial letter deciding whether he lived. That is where this file begins: not with a statistic, but with a document that took four tries to get right, sent to a man who had months, not years.

One patient’s paper trail

What Kirkland did next is the part almost no one does. He and his family posted the story on Facebook and LinkedIn, where it drew more than 6,000 shares and an offer of help from Mark Cuban. A five-person AI startup called Claimable, launched in October 2024, worked his case for free. Its co-founder, Warris Bokhari, a former NHS physician, spent hours reconstructing the file with Kirkland’s brother and sister, test by test, image by image.

The appeal’s core finding was not sympathy. It was evidence vintage. Anthem was justifying the denial with studies from 2004. Bokhari’s team pointed to research from 2018 onward showing that patients with Kirkland’s cancer who received neoadjuvant chemotherapy followed by transplant had a five-year survival rate approaching 60 percent. The appeal went up the chain at the insurer. The denial reversed.

Two details survived into the aftermath. Anthem had mislabeled Kirkland’s cancer twice, once as neuroendocrine cancer in an earlier histotripsy denial, once as the hilar variant in the transplant letter. The company said the errors did not affect the decisions, and a spokesperson, Kiryluik, told Medscape that Anthem does not use AI in coverage determinations. Kirkland’s side suspected otherwise, and Bokhari allowed that incompetent human review could produce the same output. The record cannot settle it. What the record shows is that a denial of a liver transplant contained a diagnosis the patient did not have, and the patient had to build the correction himself.

How many people are in this file

Kirkland’s letter sits inside a dataset that most insured Americans have never seen. Under the Affordable Care Act, insurers selling plans on HealthCare.gov must report their denial and appeal numbers to CMS, and KFF’s March 2026 analysis of the 2024 plan year files reads like this: insurers denied 19 percent of in-network claims and 37 percent of out-of-network claims, a combined 20 percent of everything submitted. In raw counts, about 85 million in-network denials landed on patient desks in 2024.

Denial rates vary enormously by seller. The in-network range runs from 3 percent to 36 percent, with Texas insurers spanning 12 to 36 percent, the widest spread in the country, and the lowest single state rate at 7 percent in South Dakota. By metal level, catastrophic plans deny at 22 percent, gold at 17, silver at 20, bronze at 19. Three percent of reporting insurers had in-network denial rates of 30 percent or higher in 2024, down from 17 percent in 2023, a shift KFF attributes partly to reporting changes.

Table 1: HealthCare.gov marketplace denials and appeals, 2024 plan year

Measure Value
In-network denial rate 19 percent
Out-of-network denial rate 37 percent
Combined denial rate 20 percent
In-network claims denied about 85 million
Share of denials appealed by patients under 1 percent, at least 262,982 appeals
Internal appeals upheld by insurer 66 percent
External appeals filed 5,881

Source: KFF 🔗, analysis of CMS Transparency in Coverage data, published March 2026.

The patients’ own testimony runs in parallel. A January 2026 KFF poll found 66 percent of insured adults consider delays and denials by insurers a major problem, and one third say an insurer denied a service or medication their doctor prescribed in the past two years. On the provider side, the American Medical Association’s 2024 survey found 91 percent of physicians linking prior authorization to negative clinical outcomes, with 34 percent reporting serious adverse events tied to the delays. Hospital staff spend an average of 14 business hours a week processing prior authorizations, per the AMA’s 2022 survey, and Premier’s analysis counted nearly 20 billion dollars spent by hospitals in 2022 just appealing denied claims.

What the denials sound like

Read enough denial letters and a pattern emerges in the language itself. Insurers deny fast and explain vaguely. The most common reported reason for a 2024 in-network denial is “other,” a bucket holding 36 percent of denials that insurers are not required to itemize. Administrative reasons account for 25 percent. Lack of prior authorization or referral, the reason patients assume dominates, sits at 9 percent. Only 5 percent of denials cite medical necessity, despite that being the reason patients report hearing most.

Table 2: Reported reasons for in-network denials, 2024

Reason Share of denials
Other, reason not listed 36 percent
Administrative reasons 25 percent
Excluded service 7 to 13 percent, by compilation
Prior authorization or referral missing 9 percent
Not medically necessary 5 percent

Source: KFF 🔗 2024 analysis; secondary compilations differ on the excluded-service bucket.

The letters themselves do the arguing. A newborn denied NICU coverage received an explanation addressed directly to the baby: “You are drinking from a bottle.” The case circulated through the American Hospital Association’s 2023 review of insurer practices. A Humana denial letter to Amy Hvatum, a runner with an immune disorder fighting for her Hizentra infusions, assessed her March 2025 stroke admission in one clause: “You had a small stroke.” The letter was dated March 25, two days after she was hospitalized. Humana reversed course two weeks after Hvatum appealed, her third successful appeal in a year. Her approval, when it came, expired at the end of the year, resetting the clock on the whole fight annually. Her summary of the mechanics has become the shorthand version of the system: “They love to send you the denials fast. Approvals take longer.”

Not every story ends in reversal. The son of a 67-year-old Florida woman whose lung-cancer screening MRI was repeatedly denied as unnecessary told Kaiser Health News that the delays “limited her options”; she was rushed to an emergency room six weeks later, where doctors found a massive tumor pressing against her windpipe, and she died not long after. In Pennsylvania, a college student with ulcerative colitis was flagged internally as a “high dollar account” and denied treatment his own contracted doctor called necessary; ProPublica later obtained recordings of insurer employees discussing how to justify the denials. And the case repository of the AMA preserves Correa v. Schoeck from 2016: an epilepsy patient who died from a seizure after she could not afford medication while waiting on a prior authorization.

The two conditions that keep the machine running

One explanation cannot cover this file, and the probe question has to be answered head-on: is this one broken part, or two conditions that have to hold at the same time? The record supports two, and they interlock.

The first condition is the economics of the appeal. Fewer than 1 percent of the roughly 85 million denied claims drew an appeal in 2024. External review, the binding independent process federal rules provide under 45 CFR 147.136, with a window that generally runs up to four months after a final internal denial, attracted 5,881 filings, a rounding error against the volume. The reason is not ignorance alone; it is cost asymmetry. The denial is generated in seconds, the appeal requires records, physician letters, deadlines that expire four months after a final internal denial, and weeks of hold music. Hvatum, a patient with medals on her walls and appeals in her history, put the weight of it plainly through her KFF Health News interviewer: fighting is “an exhausting process.” A denial that is never challenged simply stands. The system runs on the 99 percent who stop.

The second condition is opacity on the regulator’s side. The single largest denial reason, 36 percent, is a bucket insurers are not required to itemize. Insurers do not report which services they denied. CMS has never used the reported data for compliance or oversight, per KFF’s review, and federal tools that would let consumers compare denial practices across plans do not exist. What cannot be measured cannot be regulated, and what is not regulated does not need defending.

Remove either condition and the machine jams. If appeals were cheap, the 85 million denials would face 85 million challenges, and the 34 percent internal reversal rate plus the high external overturn rates documented for Medicare Advantage, 81 percent of 2024 appeals partially or fully overturned per KFF, would reprice the whole denial strategy. If the data were itemized and enforced, denial rates of 36 percent would surface by name. Each condition covers the other. That is why both have to go before anything changes.

The counterattack is automated now, too

The appeal side has started using the same tools the denial side does, and the Kirkland case is the template. Claimable charges patients about 50 dollars, ingests the denial letter, the plan rules and the clinical record, and drafts the kind of appeal a specialist firm would charge hundreds for. Its co-founder previously ran healthcare strategy inside Anthem itself, a detail that says much about where the industry’s own alumni believe the leverage lies. Health policy analysts have started calling the dynamic a battle of the bots: insurers scale their reviews with software, and patients scale their objections the same way. “On the provider side, there are more denials than people to process them,” Michelle Mello, the Stanford health law scholar, told Medscape about the trend. “One of the things AI tools can do is help figure out which denials are most likely to be overturned if appealed.”

The asymmetry this runs against is worth stating in numbers. The insurer side processes millions of claims a year with automation already in place. The patient side is 99 percent unautomated, disorganized, and exhausted, and its new tools reach it through social media virality, as in the Kirkland case, or through word of mouth. A 50-dollar appeal product that surfaced in October 2024 has, so far in the public record, one documented flagship win. Scaling that win to 85 million denials a year is the open question, and nothing in the regulatory file currently forces it to scale.

There are also fixes in flight, dated ones. CMS’s Interoperability and Prior Authorization Rule, finalized in January 2024, requires electronic prior authorization systems for Medicare Advantage and Medicaid managed care plans by 2026. Thirty-two states enacted prior authorization reform laws between 2021 and 2024, and California’s AB 2835 requires 24-hour decisions on emergency authorizations and 72 hours for standard ones. Yet the same reporting notes that 63 percent of Medicaid programs still run on fax-based workflows, which tells you both how deep the backlog is and how far the mandates have to travel. The 2026 electronic deadline lands in the same year this dataset was published. The next KFF brief will show whether it bent the numbers.

Who never sees this layer

The people who design the system mostly cannot observe it. Employer-sponsored plans, which cover the majority of working Americans, are not in the HealthCare.gov reporting dataset at all; KFF flags the exclusion directly. Medicare and Medicaid denials live in separate reporting universes. A benefits consultant reading the March 2026 brief sees marketplace issuers only. The HR director buying a company plan sees none of it. The patient sees an EOB letter with a code and a phone number.

The counter-evidence deserves its own sentence before the close. Most claims are paid: the same KFF file shows insurers approving about 80 percent of in-network claims without incident, and when patients fight, they win at meaningful rates, about a third of internal appeals reversed and 81 percent of Medicare Advantage appeals partially or fully overturned in 2024. Humana told KFF Health News in July 2025 that it would remove one third of its prior authorization requirements and “is committed to making the process faster and more seamless for patients and providers.” The company did reverse Hvatum’s denials, every time she appealed. The system’s defenders have a real case on the merits. The system’s critics have a better one on the defaults.

The defaults are the story. Kirkland lived because his family went viral and a startup read 2018 studies to a 2004-era rationale. Hvatum won because she is experienced, persistent and willing to spend months on hold. In Florida since 2025, Madeline Rogers’ colon surgery, Mary Barnes’ chemotherapy and Broxley Bunt’s brain tumor surgery were all denied, then all reversed after reporters started calling, with no insurer offering an explanation for the change of heart, per Treasure Coast reporting in July 2026. A coverage decision that bends to press scrutiny is telling you what it weighs. Ali Ingersoll, a quadriplegic woman denied a specialized wheelchair feature, won only after a local news station called her insurer, another reversal that required an audience. The patients without reporters, without startup allies, without a decade of appeals behind them, meet the same letters and stop at step one. The file, 85 million papers deep, is mostly made of them.

Sourcing

Data as of November 2026. Denial and appeal statistics come from KFF’s analysis of the CMS Transparency in Coverage Public Use File for the 2024 plan year, published in March 2026, and cover HealthCare.gov marketplace plans only; employer, Medicare and Medicaid claims are outside that dataset. The January 2026 KFF poll supplied the patient-perception figures. Physician-side figures come from the American Medical Association’s 2024 and 2022 surveys and a Premier Inc. analysis of 2022 hospital appeal spending. Patient narratives come from published journalism: the Kirkland file from Medscape Medical News reporting, the Hvatum file from KFF Health News’ Bill of the Month series, the Florida reversals from Treasure Coast Newspapers in July 2026, and the newborn, MRI and ulcerative colitis cases from the American Hospital Association’s review citing Kaiser Health News and ProPublica. Denial letters are quoted as quoted in those publications; this article conducted no interviews and obtained no documents directly. Where secondary compilations differ on a bucket size, as with excluded-service denials, the range is shown.

Ethics note

All quotations come from public reporting the subjects chose to participate in, and none from private forums. Named patients are quoted only where the underlying publication named them first. Reddit-sourced case material was deliberately left out, because platform posts cannot be verified against documents. The two insurer statements quoted, Humana’s 2025 pledge and Anthem’s AI denial, are presented as claims by the companies, not as established facts about their systems. No advice is offered on individual appeals; this article is reporting, not counsel.

Sources

About Global Infinity Labs

Global Infinity Labs is an AI innovation company specializing in MCP data services. This article was prepared by our expert team using insights and data provided through our MCP platforms.

Contact: support@globalinfinitylabs.com