ATLANTA — Hospitals have reduced lethal mistakes and breakdowns in care to prevent the unnecessary deaths of more than 120,000 patients in the past 18 months, said leaders of a national campaign.

"I think this campaign signals no less than a new standard of healthcare in America," said Dr. Donald Berwick, a Harvard professor who organized the campaign.

About 3,100 hospitals took part in the project, sharing mortality data and carrying out study-tested procedures that prevent infections and mistakes.

Experts say the cooperative effort was unusual for a competitive industry that traditionally avoids dealing publicly with patient-killing problems.

Berwick announced the campaign's results yesterday at a hospital conference in Atlanta. Medical mistakes were the focus of a widely noted 1999 national report that estimated 44,000 to 98,000 Americans die each year from errors.

That year, Berwick — president of the Institute for Healthcare Improvement, a Massachusetts-based nonprofit organization — challenged healthcare leaders to improve care quality.

In December 2004, he stepped up the challenge by announcing a "100,000 Lives Campaign." He set a June 14, 2006, deadline to sign up at least 2,000 U.S. hospitals in the effort and implement six types of changes.

Perhaps the best known of the six changes was to deploy rapid response teams for emergency care of patients whose vital signs suddenly deteriorate.

Another urged checks and rechecks of patient medications to protect against drug errors. A third focused on preventing surgical site infections by following certain guidelines, including giving patients antibiotics before their operations.

The hospitals also were asked to contribute monthly mortality data to Berwick's organization.

The effort was endorsed by federal health officials, health insurers, hospital industry leaders, the American Medical Association and others. About 3,100 hospitals signed up, representing about 75 percent of the nation's acute care beds.

About 86 percent sent in mortality data. Roughly a third said they were using all six measures, and more than half committed to at least three, Berwick said.

Campaign workers examined 2004 data for the participating hospitals to determine how many people were expected to die during the 18 months of the campaign.

They then checked the count of actual deaths reported. They made mathematical adjustments for severity of illnesses and for volume of cases, to make a more fair comparison of the two time periods. And they made estimates for participating hospitals that did not report data, Berwick said.

"This is estimation — it isn't counting," he said.

Various estimates placed the number of saved lives at between 115,000 and 149,000, but the best guess was 122,342, he said.

Berwick challenged hospital representatives at the conference to continue to improve. He also proposed another goal — all hospitals should implement all six changes by the beginning of 2007.