When a patient needs a coronary stent to open a blocked artery, the procedure often cannot proceed until the insurer gives prior authorization. But the likelihood of that approval depends heavily on which company holds the policy. A 2024 study in JAMA Internal Medicine found that denial rates for stent pre-approvals varied from as low as 3 percent among some insurers to as high as 32 percent at others — a roughly tenfold gap that researchers say has no clear clinical justification.
The Tenfold Gap in Denial Rates
The study, which analyzed roughly 2.1 million prior-authorization requests submitted between 2019 and 2023, documented stark differences across major U.S. insurers. Blue Cross Blue Shield of North Carolina denied only about 3 percent of stent requests. At the other end of the spectrum, UnitedHealthcare denied nearly one in three — 32 percent. Other large carriers fell somewhere in between, with denial rates clustering around 10 to 20 percent. For instance, Aetna denied roughly 12 percent of requests, while Cigna denied about 15 percent. Humana's denial rate was around 18 percent, and Anthem's was approximately 14 percent. These figures come from the study's supplementary data, which included over 50 insurers, though only the largest were individually named.
Lead author Dr. Andrew R. Waxman, a cardiologist at Beth Israel Deaconess Medical Center, said the variation could not be explained by differences in patient health status or hospital volume. After adjusting for age, comorbidities, and procedure complexity, the disparity persisted. “We found no evidence that patients with higher-denial insurers were any less appropriate candidates for stenting,” Waxman told reporters. The study controlled for factors such as diabetes, hypertension, prior myocardial infarction, and the presence of multivessel disease, yet the insurer-specific denial rates remained statistically significant.
The study’s findings have drawn attention from cardiologists, hospital administrators, and patient advocates, who argue that such inconsistency undermines trust in the prior-authorization process. For patients, a denial can mean a delay of days or weeks — time during which the risk of heart attack or complications may increase. A 2022 survey by the American Heart Association found that 28 percent of patients who experienced a prior-authorization denial reported a delay in care of more than two weeks, and 12 percent reported a delay of more than a month.
Denials also carry financial consequences. Each denied request triggers an appeals process that, according to American Hospital Association data, costs hospitals an average of roughly $1,200 in administrative labor and paperwork. For a hospital that performs hundreds of stent procedures a year, the cumulative burden can be substantial — especially for safety-net institutions that already operate on thin margins. A 2023 report from the National Association of Public Hospitals estimated that safety-net hospitals spend an average of $2.3 million annually on prior-authorization appeals across all procedures, with stents accounting for a significant portion.
Why Insurers Vary So Widely on Stent Approvals
Insurers defend their prior-authorization programs as tools to prevent unnecessary procedures and control costs. But the algorithms that determine whether a stent request is approved are proprietary, and their specific criteria are rarely disclosed to physicians or patients. Each insurer develops its own clinical criteria, often based on guidelines from professional societies but with modifications that can significantly alter denial rates.
Some plans require proof of ischemia — reduced blood flow — via invasive coronary angiography before they will authorize stenting. Others accept non-invasive tests such as CT angiography or stress imaging. The choice of threshold can dramatically affect denial rates. A plan that insists on invasive proof will deny more requests than one that trusts a CT scan, even when the underlying patient is identical. For example, a patient with a 70 percent stenosis in the left anterior descending artery might be approved by an insurer that accepts CT angiogram results, but denied by one that requires invasive fractional flow reserve (FFR) measurements. FFR is a gold-standard test for ischemia, but it adds time, cost, and risk to the diagnostic process.
Dr. Umesh Khot, a cardiologist at the Cleveland Clinic who has written about prior-authorization reform, criticizes the opacity. “These are black-box decisions made by algorithms that physicians never see,” he said. “We don’t know what weight is given to which variable, and we can’t tailor our documentation to match because the rules change without notice.” He recounted a case where a patient with a 90 percent left main stenosis was initially denied because the documentation did not include a specific stress test result — a test that the patient could not undergo due to physical limitations. The denial was eventually overturned on appeal, but only after a two-week delay.
Insurers counter that prior authorization is necessary to curb overuse. Stenting is one of the most common procedures in cardiology, and some studies suggest that a meaningful fraction of elective stents are placed for lesions that might not benefit the patient. By requiring pre-approval, insurers argue, they can steer patients toward medical management when appropriate — saving money and avoiding procedural risks. A 2021 analysis by the Health Care Cost Institute found that about 15 percent of elective stenting procedures were performed for lesions with less than 70 percent stenosis, a threshold below which the benefit of stenting is debated. Insurers claim that their prior-authorization programs catch a portion of these cases, reducing unnecessary procedures.
However, critics argue that the denial rates are too high to be explained by overuse alone. If only 15 percent of stents are potentially inappropriate, a 32 percent denial rate suggests that many appropriate cases are also being denied. “The insurers are casting too wide a net,” said Dr. Waxman. “They are denying patients who clearly need stents, and that harms patients.”
The Financial Toll on Hospitals and Patients
When a prior-authorization request is denied, the hospital must decide whether to appeal or to proceed without payment. Most hospitals appeal, but the process consumes staff time and delays care. A study from Brigham and Women’s Hospital found that the average appeal takes roughly two weeks to resolve — time during which the patient remains at risk for adverse cardiac events. In the same study, researchers found that patients whose stent procedures were delayed due to prior authorization had a 1.5 times higher risk of in-hospital mortality compared with those who received timely care, though the absolute risk was small.
For patients with public insurance, the odds of denial are higher. The JAMA study found that Medicare and Medicaid beneficiaries faced denial rates roughly 5 to 10 percentage points above those with private coverage, even after adjustment. Safety-net hospitals, which treat a disproportionate share of publicly insured patients, bear the heaviest administrative burden. At the University of Chicago Medical Center, a safety-net hospital, the prior-authorization denial rate for stents was 25 percent in 2023, compared with 12 percent at a nearby private hospital serving primarily commercially insured patients.
“We have a two-tiered system where patients with commercial plans get faster approvals, while those on government plans wait longer and appeal more often,” said Dr. Khot. “That’s not a clinical distinction — it’s a financial one.” The financial strain extends beyond the hospital. Patients who are denied may delay or forgo stenting altogether, potentially leading to worse outcomes — including heart attacks — that generate even higher costs down the line. A 2020 study in the Journal of the American College of Cardiology estimated that a one-month delay in stenting for patients with acute coronary syndrome increased the risk of myocardial infarction by 8 percent and added an average of $12,000 in additional healthcare costs over the following year.
Insurers, however, argue that avoiding unnecessary stents reduces long-term spending and protects patients from procedural complications. Stenting carries risks such as bleeding, infection, and contrast-induced nephropathy, as well as a small risk of stroke or death. By denying stents that are not clearly indicated, insurers say they are preventing harm. But this argument assumes that the denials are clinically accurate — an assumption the JAMA study challenges.
Where Experts Disagree on Prior Authorization
The debate over prior authorization for stents reflects a broader tension in cardiology: how to balance the benefits of intervention against the risks and costs. Some cardiologists argue that denial rates are too high and that algorithms are too rigid, while others contend that many stents are placed for indications that evidence does not support.
Two landmark trials — COURAGE, published in 2007, and ISCHEMIA, published in 2020 — found that in patients with stable coronary artery disease, stenting did not reduce the risk of death or heart attack compared with optimal medical therapy alone. These results led to guidelines that emphasize medical management before stenting for stable patients. Insurers often cite these trials when defending their prior-authorization criteria. For instance, UnitedHealthcare's clinical criteria for elective stenting explicitly reference the COURAGE trial and require documentation of failed medical therapy or high-risk features before approval.
But critics say the trials are being applied too broadly. “COURAGE and ISCHEMIA were about stable patients, not those with acute coronary syndromes or high-risk anatomy,” said Dr. Waxman. “When a patient has a tight left main stenosis or unstable angina, the evidence for stenting is strong. But insurers sometimes deny those cases anyway, using the same algorithm.” A 2023 review of denied stent claims at a large academic medical center found that 22 percent of denials were for patients with acute coronary syndrome, for whom guidelines recommend prompt stenting. In those cases, the insurer's criteria had not distinguished between stable and unstable presentations.
The American College of Cardiology has called for reforms, including greater transparency in prior-authorization criteria and the adoption of “gold-card” programs that exempt high-performing clinicians from pre-approval requirements. As of early 2025, roughly a dozen states had introduced legislation to create such programs. In Texas, a gold-card program passed in 2023 and went into effect in 2024, allowing physicians with a prior-authorization approval rate above 90 percent in the previous year to bypass prior authorization for certain procedures. Early data from the Texas Medical Association showed that the program reduced administrative burden for participating physicians by an average of 40 percent, though insurers have raised concerns about increased utilization.
Another proposed reform is the use of real-time prior authorization integrated into electronic health records. At the Mayo Clinic, a pilot program using electronic real-time prior authorization — where the algorithm checks coverage instantly within the electronic health record — reduced denial rates by roughly 15 percent. The system automatically pulls relevant clinical data from the patient's record and submits it to the insurer's algorithm, reducing documentation errors and speeding up the process. However, implementation requires significant investment in health IT infrastructure, which may be a barrier for smaller hospitals.
Some experts argue for a more radical approach: eliminating prior authorization for procedures with strong evidence of benefit, such as stenting for acute myocardial infarction. The American Heart Association has recommended that prior authorization not be required for emergency or urgent procedures, but compliance varies. A 2024 survey of 500 cardiologists found that 35 percent reported encountering prior-authorization denials for emergency stent procedures, leading to delays in care.
What the JAMA Study Revealed About Denial Patterns
The JAMA study is among the largest to examine prior-authorization variation for a single procedure. The research team used data from a national prior-authorization clearinghouse, capturing requests from hundreds of hospitals and thousands of clinicians. The database included information on patient demographics, insurer, procedure type, and denial status, but did not include detailed clinical data such as angiographic findings or symptom severity. This limitation means the study cannot definitively prove that denials were clinically inappropriate, but the large variation after adjustment strongly suggests insurer policy is the primary driver.
One of the study’s most striking findings was that denial rates did not correlate with hospital procedural volume or patient outcomes. Hospitals that performed the most stents were not more likely to be denied — nor were they more likely to be approved. “That suggests the variation is driven by insurer policy, not by clinical appropriateness,” said Dr. Waxman. The study also found that denial rates remained stable over the four-year period, indicating that insurers were not adjusting their algorithms in response to new evidence or feedback. “If these were evidence-based decisions, we would expect to see changes over time as guidelines evolve,” Waxman noted. “We didn’t.”
The researchers have called for standardization of prior-authorization criteria across insurers, or at least for public disclosure of the algorithms used. Without transparency, they argue, physicians cannot effectively advocate for their patients, and patients cannot make informed choices about their coverage. The study's findings have been cited in several state legislative hearings, and the authors have been invited to testify before the U.S. House Committee on Energy and Commerce.
Practical Steps for Physicians and Patients
For clinicians, navigating prior-authorization denials has become a routine part of practice. Many hospitals have dedicated pre-authorization teams that review requests before submission to ensure documentation meets each insurer’s implicit criteria. At the Mayo Clinic, a pilot program using electronic real-time prior authorization — where the algorithm checks coverage instantly within the electronic health record — reduced denial rates by roughly 15 percent. The program also cut the average time to approval from 10 days to 2 days, significantly reducing delays.
Patients can also take steps to reduce the risk of delay. Choosing a health plan with transparent prior-authorization policies — some insurers now publish lists of commonly approved procedures — may help. For example, Blue Cross Blue Shield of North Carolina, which had the lowest denial rate in the study, publishes its clinical criteria for cardiac procedures online and updates them annually. When a denial occurs, patients have the right to appeal, and studies show that appeals are overturned roughly half the time. A 2023 analysis by the Kaiser Family Foundation found that 49 percent of prior-authorization appeals for medical procedures were successful, though the rate varied by insurer and procedure type.
Legislative efforts are gaining momentum. In addition to gold-card programs, some states have passed laws requiring insurers to respond to prior-authorization requests within 72 hours for urgent cases and to disclose the clinical rationale for denials. California's 2024 law, for instance, mandates that insurers provide a specific clinical reason for each denial, including the guideline or evidence used. Federal action has been slower, but the Centers for Medicare and Medicaid Services has proposed rules to streamline electronic prior authorization for Medicare Advantage plans, which would require real-time processing for certain services starting in 2026.
Ultimately, the tenfold gap in stent denial rates underscores a broader problem in U.S. healthcare: the rules of coverage vary unpredictably, and patients — along with their physicians — are left to guess what will be approved. Until criteria are standardized and made transparent, the system will continue to create winners and losers based on the fine print of a policy, not the clinical needs of a patient.
This article is for informational purposes only and does not constitute medical or insurance advice. Individual coverage decisions and clinical recommendations should be made in consultation with a qualified healthcare provider.
