In a study examining what specialists may charge to out-of-network or uninsured patients, radiologists, neurosurgeons and emergency physicians ranked near the top of the list of highest markups compared to Medicare rates.

Written by John Hopkins University researchers Ge Bai, PhD, and Gerard Anderson, PhD, and published in JAMA, the study analyzed 2014 Medicare utilization and payment data, comparing the charges of more than 400,000 physicians to Medicare rates.

Anesthesiologists topped the list, charging an average of 5.8 times what Medicare reimburses and making up 55 percent of the more than 10,700 physicians identified as having “high excess charges.” Interventional radiologist were next highest, charging an average of 4.5 times the Meidcare rate, followed by emergency medicine physicians (four times), pathologists (four times), neurosurgeons (four times) and diagnostic radiologists (3.8 times).

Overall, median excess charges were 2.5 times higher than what Medicare pays across all specialties. The areas with higher markups indicate a greater risk for “surprise” medical bills for patients when they receive services from a specialist who, unbeknownst to patients, isn’t in their network.

“Physician excess charge was higher for specialties in which patients have fewer opportunities to choose a physician or be informed of the physician’s network status (eg, anesthesiology),” Bai and Anderson wrote. “To our knowledge, there is no study indicating that Medicare systematically underpays these specialties compared with other specialties. Therefore, the relatively high excess charges of these specialties are more likely to be caused by interspecialty variation in charges than by interspecialty variation in Medicare allowable rates.”

The study couldn’t account for the number of uninsured and out-of-network patients actually treated or what discounts they may have been given. The issue of unexpected bills has been taken up by legislators in several states, with laws tying what specialists can charge to Medicare rates being enacted in California and New York.

The American College of Emergency Physicians bashed the study, saying it’s “not true” to portray charges above Medicare rates as excessive and pointing the finger at insurance companies for issues with out-of-network charges.

“They have taken gross advantage of patients and emergency medical providers since the ACA, arbitrarily slashing payments to physicians,” ACEP President Rebecca Parker said in a statement. “The (Emergency Medical Treatment and Labor Act) mandate gives the insurance industry the upper hand and can exploit the situation, because the doctors have to see all patients, regardless of insurance status or ability to pay.”

Parker also said such surprise charges are rare in emergency medicine, citing a study from ACEP’s Florida chapter. A separate Yale University study published in Novemeber 2016 came to a different conclusion, saying 22 percent of patients who went to an in-network emergency department received some treatment from an out-of-network physician during their visit.