Hospitals, for their part, are afraid that the change in policy could cut reimbursement even further and reduce revenue.

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While UnitedHealth's policy is different from Indianapolis-based Anthem's—the latter has been denying coverage for ER visits that it decides were not emergencies after the fact—they have a common goal: cutting insurers' costs for ER claims. And between the two, hospitals' emergency room payments—as well as hospitals' bottom lines—could be in real trouble.

"Some hospitals are going to be hit financially, are going to be paid less, either through straight denials or through downcoding to a Level 3, and it is going to be a big hit for some hospitals on the ER revenue … unless they can truly justify they are providing the care or the services that's really needed," Dr. Christopher Stanley, a director at consulting firm Navigant who worked for UnitedHealthcare for nearly 10 years, is quoted saying in the report about UnitedHealthcare's ED policy.

Anthem's policy is pushing both patients and hospitals to be sure that an emergency room visit is really an emergency, while UnitedHealth's policy is aimed at making sure that emergency department claims coded for the highest acuity patients are justified to be filed at that level. Both Aetna's and UnitedHealth's new policies are after-the-fact evaluations.

UnitedHealth will use subsidiary Optum's tool, the EDC Analyzer, the report says, "to audit facility claims submitted with Level 4 and 5 codes after a patient visits the ED and is sent home. The Optum tool takes into account the patient's medical issue, co-morbidities, and the diagnostic services performed during the ED visit to determine what UnitedHealth believes is the appropriate code."

According to the report, "Emergency room facility fees are coded on a scale of 1 to 5, reflecting the complexity of care delivered and the amount of resources the ER devoted to the patient. Level 1 codes are for low-acuity conditions, while Level 4 and 5 codes are for the most serious conditions that require lots of hands-on treatment, such as blunt trauma or severe infections. Higher codes are more expensive for insurers."

The new policy applies to all facilities, it adds, including free-standing emergency departments, that submit ED claims with level 4 and 5 codes for members of the insurer's commercial plans and Medicare Advantage plans.

There are a few exceptions; the policy does not apply to claims for patients who end up being admitted to the hospital from the ED, critical care patients, patients younger than two years old, or patients who died in the ED. It also excludes claims with certain diagnoses that, when treated in the ED, often require greater than average resources, such as significant nursing time, according to a UnitedHealthcare bulletin.

In the report, a UnitedHealthcare spokesman says that the policy was devised in response to claims data indicating that the frequency of claims with Level 4 and 5 severity codes has risen by more than 50 percent between 2007–2016. The company estimates that the more frequent use of those codes has increased U.S. healthcare costs by more than $1.5 billion, while also causing patients to spend hundreds more in medical bills.