WALNUT CREEK, Calif. — When Al Swanson first heard about a program in which doctors make house calls to chronically ill seniors, he figured it must be a scam.

He could sign up, he was told, and receive a doctor's cell phone number for round-the-clock access, with home visits as needed.

Better yet, it would not cost him a dime beyond his standard fee-for-service Medicare.

"It sounded too good to be true," said the 66-year-old Emeryville, Calif., resident.

It wasn't.

In a return to a bygone era, with a modern-day twist, Swanson is one of nearly 15,000 seniors in California, Florida and Texas receiving house calls from doctors as part of a three-year Medicare demonstration project, which began in October 2005.

The idea behind it is simple. Many of the frail elderly with multiple health problems make repeated trips to hospital emergency rooms and intensive care units, where they rack up hefty bills.

Five percent of the sickest Medicare beneficiaries account for nearly 45 percent of the total costs of the Medicare program.

By giving such people quality, preventive care at home, federal officials say they can keep them healthier and avoid hospitalizations, thus saving Medicare, and taxpayers, money.

Care Level Management, a Woodland Hills, Calif.-based company, has reported success with a similar model designed for HMOs. Now the company is overseeing the Medicare trial.

"The population that we manage (is) the sickest of the sick," said Dr. Henri Becker, a co-founder of the firm.

"They are a very old population and basically what we have observed is they have difficulty accessing ambulatory care and their primary care physician. They have mobility issues, and also the primary care physician cannot really be available in his office 24/7."

By encouraging such people to call a doctor as soon as their condition changes, Becker said, the problem can be diagnosed and treated at an earlier stage, before it escalates.

When Jeff Flick, the regional administrator for Medicare, heard about the program, he persuaded top-ranking Medicare officials to give it a try, with the goal of broadening it if the economics pencil out.

It is too early to determine the trial's success, but one of the biggest problems so far has been telling Medicare beneficiaries they cannot participate, Flick said.

Only those who are invited and meet strict criteria, including being chronically ill, can join.

It's a piece of Americana that virtually vanished in the 1980s and 1990s: The doctor appearing at the front door with a little black bag.

But in recent years, house calls have enjoyed a resurgence as the population ages, advances in technology provide more portable medical devices, and a 1998 change in Medicare reimbursement rates boosted by nearly 50 percent the payment for house calls.

From 1998 to 2004, the number of house calls nationwide jumped from 1.4 million annually to more than 2 million. An estimated 3,000 physicians now make house calls full time.

Doctors who make house calls say they like being able to spend more time with their patients, and they can pick up problems that would be missed in a quick office visit.

Office visits today can be fast-paced. Many primary care physicians say they feel pressured to see patients every 15 or 20 minutes to make ends meet. The Care Level Management physicians, by contrast, typically spend 45 minutes to an hour with each patient, and possibly 90 minutes or more on their initial visit.

Dr. Doris Purcell saw more than 20 patients a day when she was in private practice. She had a caseload of 1,000 to 1,600 patients.

Now, as part of the Medicare demonstration project for the San Francisco and Peninsula region, she sees six to eight patients a day, with a caseload of 150.

The extra time, she says, has changed her relationship with her patients.

"I've never been happier," she said. "This is it. This is what I was meant to do. Patients and doctors alike are really frustrated with medicine and this is a way for us to reconnect."

While many of the participants rave about the program, the big question will be whether it works financially.

Care Level Management believes it can produce enough savings to pay the physicians, obtain a management fee for the firm, and have money left over for the Medicare system. Whether it will succeed remains to be seen.

Even if the program is a huge success, there is little chance that it will be extended to healthier Medicare beneficiaries. What makes it work, at least in theory, is the high cost of taking care of the chronically ill.