By Lisa Rapaport

A growing number of Americans treated at hospitals that are part of their insurance networks are getting billed for out-of-network care, a U.S. study suggests.

The proportion of emergency room visits to in-network hospitals that result in out-of-network bills surged from 32.3% to 42.8% from 2010 to 2016, the study found. Over the same period, the proportion of inpatient hospital admissions to in-network hospitals that result in out-of-network bill surged from 26.3% to 42%.

Patients’ tabs for these out-of-network bills has climbed too, from an average of $220 to $628 for ER visits and from an average of $804 to $2,040 for inpatient hospital admissions.

“Out-of-network billing in both the inpatient and emergency room settings is common and has become more common over time,” said Dr. Eric Sun, lead author of the study and a researcher at Stanford University Medical Center in California.

“The amount of money involved can be a significant burden for many patients,” Sun said by email. “Even if they receive care at an in-network hospital, they may still face out-of-network bills.”

In the U.S., physicians in an insurer’s network have agreed to accept a set amount from the insurer as payment in full for their services. Out-of-network physicians, however, are not constrained by any in-network agreements and can seek additional payment from patients, a practice known as out-of-network balance billing.

At many hospitals in an insurer’s network, some of the physicians may still be out-of-network, particularly for specialties like anesthesiology. This can lead to balance billing surprises even when patients make a point to seek care at an in-network hospital.

For the current study, researchers examined data on more than 6.4 million inpatient admissions and 17 million emergency room visits for patients with private health insurance in all 50 U.S. states.

For ER visits, out-of-network billing was particularly common for ambulance services: 85.6% of ambulance encounters resulted in balance billing, researchers report in JAMA Internal Medicine.

About one-third of patients treated by emergency physicians at in-network hospitals got balance billed, as did more than one in five patients receiving care from an internist or an anesthesiologist.

With inpatient admissions, specialties with the most balance billing included radiology, emergency medicine, internal medicine, anesthesiology, cardiology, pathology, ambulance transport, family practice, and obstetrics and gynecology.

Patients who had balance bills in the top 10% faced more than $1,000 of out-of-pocket costs for ED care and more than $3,000 out-of-pocket for inpatient admissions, the study found.

One limitation of the study is that researchers didn’t know for certain how many balance bills were truly a surprise to patients. But most people probably don’t expect these bills for care at an in-network hospital, the study team notes.

Researchers also lacked data on how much of balance bills patients actually paid. It’s possible some people didn’t pay all or part of these bills.

Still, it’s easy to see how these bills would catch patients off guard, said Dr. Robert Steinbrook, editor at large of JAMA Internal Medicine and an adjunct professor at Yale University School of Medicine in New Haven, Connecticut.

“In an emergency, a patient is often unable to choose the emergency department, the physicians or the ambulance service,” Steinbrook, author of an editorial accompanying the study, said by email. “And, a patient may seek routine in-network care at an inpatient hospital or outpatient facility, only to later find out that in-network physicians were not available to care for them.”

SOURCE: JAMA Internal Medicine, online August 12, 2019.