Donning a protective gown, rubber gloves, and a face mask, Dayna Gurley looks as if she's heading into surgery. But Gurley is a medical social worker charged with figuring out why her client has been in three Houston hospitals in the last month.

The patient, who has chronic massive ulcers, AIDS, and auditory hallucinations, frequently is homeless, with no family to help him.

"It's almost like self-sabotage," Gurley said about her many attempts to steady his life. "We get really close to an important doctor's appointment or getting him connected with stable housing, and his impulsiveness gets in the way of that."

He is one of health care's "super-utilizers" — people with complex problems who frequent emergency rooms for ailments more aptly handled by primary-care doctors and social workers. They make up just 5 percent of the U.S. population, but account for 50 percent of health-care spending.

As health-care costs continue to rise, hospitals and doctors are trying to figure out how to find these patients and get to the root of their problems.

An effort to do just that started in Camden more than a decade ago. Inspired by the way police departments mapped crime data to detect "hot spots," family physician Jeffrey Brenner dug into ambulance records and emergency department data to show how high-cost patients were shuttling between city hospitals.

"In America, we're medicalizing social problems and we're criminalizing social problems, and we're wasting huge amounts of public resources," Brenner said. "We have the wrong tools to solve the wrong problem."

To steer patients away from expensive emergency care and push health systems to change the way they do business, the Affordable Care Act funds programs called Accountable Care Organizations. These are networks of hospitals, physicians, and others who team up to improve care, lower costs, and reap the savings.

Brenner's team at the Camden Coalition includes Latonya Oliver and Bill Nice, social workers who seek out patients such as Peter Bowser in local neighborhoods. Bowser was once homeless and went to the emergency department nearly 30 times in one year.

But after Oliver and Nice helped get a permanent roof over his head, Bowser's trips to the ER all but stopped.

"I think you'd prefer to spend your time here than in the hospital any day of the week," Nice said to Bowser on a recent afternoon, at the kitchen table in his tidy apartment.

This high touch, data-driven approach has yielded big savings. ER visits for the first group of patients dropped by 40 percent, cutting monthly hospital bills from $1.2 million dollars to $500,000.

Since then, Brenner has sought to spread the model around the country. One example is the Patient Care Intervention Center in Houston, a sprawling city desperate to aid its sickest and most isolated patients.

While the more than 100 hospitals here typically know their own super-utilizers, they had no way of knowing the top users across the entire city.

Tackling that problem took unprecedented planning among typically disjointed city and county agencies, hospitals, and nonprofits. Now, many of the hospitals in Houston and the Fire Department pool their data and send it to the Patient Care Intervention Center,  where it is combined into one database so that people who most need help can get it.

The results of these intensive interventions can be stunning.

Timmy Williams was dying when Dayna Gurley found him.

He was holed up at home and reeling from untreated HIV that had progressed to AIDS. He couldn't take care of his young son and cycled through Houston's hospitals.

"When we first met Timmy, he was very hard to engage," Gurley recalled. "We knew that he probably was not taking any of his medication, and he was very skinny."

She arranged for a home aide to care for Williams seven days a week and got his apartment cleaned and the lights turned back on.

Now, Williams' HIV is undetectable and his health — and life — have been steadied.

In the two years since Houston's Patient Care Intervention Center has been up and running, costs for those in the program have gone down 83 percent and hospital visits by 70 percent.

But it can be difficult to keep these programs moving. Often, insurance companies and government payers reap those savings, rather than hospitals. Center founder David Buck and Dayna Gurley were once banned from a Houston hospital whose executives feared losing money if their high-cost patients stopped showing up.

"Nobody wants to take ownership of any of it," David Buck said, his voice bristling with frustration. "The people just want ownership of what they have authority over, and that's really the issue: Each of these areas are little fiefdoms."

Adding more uncertainty to these efforts: the possible impact of the Trump administration and congressional Republican's "repeal and replace" efforts on the health-care system. In Camden, even Brenner is less optimistic than he once was. His office now overflows with pillows and kitchenware for clients whom the Camden Coalition is trying to place in housing. And he thinks homelessness and entrenched financial interests in health care are the biggest barriers.

"I think this is going to take a lot longer than I ever imagined," he said. "I think we're in a 20-year arc of recalibrating and rethinking what is health and what's health care. What's the purpose of our health-care system? What are we trying to accomplish?"