Hospitals in Maryland are renowned for their patient care. But for the past decade, these nonprofit institutions have also quietly operated under an innovative statewide experiment in cost controls.

Executives say the system, where they are rewarded for keeping patients out of their hospitals and getting more of them preventive and outpatient care, has already saved more than a billion dollars.

The executives have considered this a success — until now.

Some hospitals are getting busier. That’s because the population in Maryland is getting older. Their care is getting more complex and treatments more expensive. Droves of patients are also coming through overwhelmed emergency rooms, pushing wait times to some of the longest in the country.

Hospitals say the system is on the verge of crisis, with access to care increasingly at stake.

“We can’t have policies that limit access to appropriate care and don’t allow hospitals to be paid appropriately for care that is provided,” said Kevin Sowers, CEO of Johns Hopkins Health System.

State regulators say they are primed to help hospitals, with public debate over the increased funding expected at next month’s meeting of the little-known agency that oversees their budgets.

The ultimate fix — and total cost — isn’t yet clear. But any move to boost hospitals’ bottom lines will almost guarantee higher bills for patients and their insurers, observers and advocates say.

“These hospitals operate on billion-dollar budgets, and they no doubt provide their CEOs with big bonuses while making sure they charge everyone, including very low-income people,” patient advocate Linda Haller said in an interview. “Why do they need so much more money?”

Under the system, state regulators set rates for everything from childbirth to heart bypass surgery at each hospital and cap the annual total hospitals can bring in from patient care.

The hospitals can tweak the rates to ensure they come in under their caps. If they succeed in encouraging their patients to get preventive care or less expensive care in outpatient doctor offices and surgery centers, they can keep the savings.

Officials say the system saved $1.4 billion in federal health care spending in the first five years and $300 million through 2023. Some hospitals say, however, they are now struggling to come in under their budgets. They are providing more care for the same money.

Executives at Johns Hopkins, as well as the University of Maryland Medical System and Luminis Health, say it’s a complex problem.

The overall number of hospital beds has fallen over the last decade by more than 7%. That initially was due to decreased need at some hospitals, but now, the officials say, may be because hospitals are trying to keep out patients.

That has left some hospitals with too little space to treat patients. Others have more space, but not enough financial resources to provide their care.

Victoria W. Bayless, chief executive officer of Luminis Health, said big hospitals are strained because they treat the sickest patients. But smaller community hospitals like hers can also quickly become overwhelmed when they don’t turn patients away.

“Anne Arundel Medical Center has 380 licensed beds, but we routinely find ourselves with a census of over 420 patients because we’re trying to keep our doors open, staff every bed and not put ambulances on diversion,” she said.

For their part, regulators at the state’s Health Services Cost Review Commission are scheduling meetings with hospitals, insurers and the public to find the combination required to ensure hospitals get enough money to operate properly, maintain access and still invest in community programs aimed at keeping people healthy.

At the same time, they must keep spending in check, which is the system’s goal. And it’s also required by federal authorities who pay the bills for Medicare and Medicaid patients — and could make changes as they seek to cut federal spending.

Diane Dimeo said she has seen the crisis firsthand after she tried to get hospital care last December.

She went to an urgent care center near her home in Havre de Grace because of some suspicious bruising around her knee after surgery. But the center sent her to an emergency room. And there she sat for five hours before she left without ever seeing a doctor.

“There were eight people there, and I’m not sure why I wasn’t seen,” she said. “They kept saying they were short-handed. It was a waste of time.”

Haller, the patient advocate, said she’s heard a lot of similar stories. And when patients face long emergency wait times or can’t schedule a surgery, the system doesn’t feel so “patient-centered.” When they face big bills, they wonder what the hospitals, all nonprofit in Maryland, are doing with the money they get.

Jonathan Weiner, professor of health policy and management at the Johns Hopkins Bloomberg School of Public Health, said despite long lines at ERs, there have been successes under the price control system.

“The system has led to lower hospital admissions and savings for Medicare, and some other states are looking to copy us,” he said. “But there are trade-offs. Public and private insurers pay more per hospitalization here than in most other states. And while the Maryland model has targeted health improvements outside of hospitals, to date these achievements have been modest.”

Dr. Joshua Sharfstein, chair of the state rate-setting board, said the state agency is “not a public utility.” But he said the agency can still tell when hospitals treat fewer patients and can shift funding from there to the hospital in a neighboring county that does see the extra patients.

“The challenge is figuring out how to set the budgets” so hospitals can continue seeing all the patients in their community, said Sharfstein, also a vice dean of the Johns Hopkins Bloomberg School of Public Health.

There are other questions that will effect how successful this experiment in hospital cost control will be.

Dr. Ben Lowentritt, a surgeon with privileges at four hospitals and a past president of the state’s medical society, said hospitals face pressure to cut hours for needed specialists or limit needed surgeries in order to balance their books.

He added that while many may bemoan emergency room wait times, there is little incentive for hospitals to add staff or beds because if they see and admit people more quickly, “it will hurt them financially,” he said. “It might be purposeful or just necessary, but it’s the result.”

At risk are people like Dimeo. She ended up seeing her primary care doctor and suffered no complications, which is what the Maryland system is supposed to encourage. But she can’t help but wonder what would have happened if it was a true emergency.

A hospital nurse called two days later, not to ask about her knee, but the spiking blood pressure the staff found when they triaged her in the waiting room.

“Where will I go next time?” she said. “I don’t know.”