The mayor has not yet named a successor to Benjamin Chu, who announced last month that he would leave his post as president of the city’s Health and Hospitals Corporation to become president of the Kaiser Foundation Health Plan’s Southern California Region.

But whoever takes the position will be able to build on Dr. Chu’s dramatic transformation of the agency, which has a $4.5 billion annual budget and serves more than 1.3 million residents annually with a network of 11 hospitals and more than 100 clinics.

Dr. Chu has earned the corporation national recognition in the face of severe budget cuts and, particularly in the area of fringe benefits and pensions, rising costs. “It really is an amazing accomplishment that we didn’t crash in this environment,” he said.

The financial pressures are constant – just last week, Mayor Bloomberg, on a visit to Albany, protested proposed changes to Medicaid that would cost the city an estimated $275 million a year – but Dr. Chu sought never to let financial constraints stop the corporation from fulfilling its mission, which he described as: “Not just to see patients, but to improve outcomes for patients.”

One legacy of Dr. Chu’s tenure is an aggressive agenda on capital spending. Construction projects came with a $1.2 billion price tag. Five major facilities are opening in 2005: the Bellevue Ambulatory Care building, which will start taking patients in a few weeks; a new building at Jacobi Hospital in the Bronx; a bed tower at Coney Island Hospital; an emergency room building at Elmhurst Hospital, and a partial rebuilding of Kings County Hospital in Brooklyn. Meanwhile, the corporation plans to break ground in the fall on a new Harlem Hospital, and projects at Lincoln Hospital in the Bronx and Queens Hospital are under way.

In addition, every hospital is now equipped with MRIs. “When I started, there were only a handful of hospitals that had MRIs,” Dr. Chu said. “To have an acute-care hospital without one is a big gap.”

Another big expense was an overhaul of information technology. When he started as president, technology projects were at various stages of implementation. He decided to forge full steam ahead, making upgrades system wide. “Basically, what I did is I said, ‘This is ridiculous, you can’t do this slowly,’ ” Dr. Chu said.

Dr. Chu chose to install Computerized Physician Entry Order, which replaces the illegible scribbles of a doctor’s orders with a computerized record. “It’s a huge savings in terms of time, but, much more important, it’s a patient safety issue,” Dr. Chu said. “You don’t have the errors that happen when you can’t read the orders.” It put the corporation on the cutting edge: Only 10% of American hospitals have CPEO, as it is known, Dr. Chu said.

He also helped implement a digital imaging system that allows information on patients, such as X-rays and EKGs, to be pulled up on the screen within seconds.

The ability to track and retrieve information is a great help to a system in which 900,000 patients seek continual routine care at the clinics.

As with the construction projects, Dr. Chu wasn’t scared of expense. His information-technology initiative cost as much as $500 million to implement. “That’s a big number,” he said, “but the result is better coordination of care, better efficiency, and a reduction in the length of stay for our patients.” In the past three years, he said, the average length of stay at the city hospitals has been reduced to 4.8 days from 5.4 days.

Dr. Chu advocates measuring progress in hard numbers. That prompted his call for a redesign in ambulatory care, with the aim of reducing the time of visits to 60 minutes or less. The duration of the average visit has been reduced to 72 minutes from 145 minutes, Dr. Chu said. “Not only the patients feel better, the staff feels better, because they no longer have patients yelling at them,” he said.

A payoff: The national organization that accredits and rates hospitals, the Joint Commission on Accreditation of Healthcare Organizations, recently gave the hospitals ratings in the 90s, on a scale of a 100.

Dr. Chu also found ways for the hospitals to cut costs and increase revenue. For example, the number of uninsured patients seen at the hospitals decreased to 430,000 from 530,000. The change can be traced to Dr. Chu’s initiative to enroll qualified patients in the corporation’s MetroPlus health-care program. In his years as president, enrollment has increased to 220,000 members from 80,000 members, and annual income has increased to $440 million from $130 million.

“The other thing we really took a look at was our billing practices,” Dr. Chu said. “We made sure we billed for every single thing. Not surprisingly, we found hundreds of millions of dollars.”

His tenure at the corporation – “the most rewarding three years in my professional life” – has been a transforming experience for Dr. Chu.

New York City will never be far from his thoughts. He grew up in Chinatown and has worked here most of his professional life, with the exception of a one-year stint working on Bill Bradley’s presidential campaign and his four years of college at Yale. He earned his medical degree at New York University and a master’s in public health from Columbia University.

He said he did not seek the position with Kaiser, but he knew it was a good next step. He has his sights set on a national leadership role in health-care reform, most likely in Washington.

“For someone who wants to make a dent on reforming the U.S. healthcare system,” he said, “having that kind of health plan exposure and responsibility, as well as having some experience in a completely different region in this country, is just a logical career move.”