The Senate has approved an identical measure. The House's 428-3 vote means the bill will go to President Bush, who is expected to sign it.

Backers called the patient safety legislation a step toward encouraging doctors and other healthcare providers to report mistakes and hazards. Common medical errors include giving patients the wrong medications and lax sanitary practices, which can lead to infections at hospitals and nursing homes.

Such problems had received relatively little national attention until recently, despite the death toll. By comparison, highway accidents claimed 42,800 lives last year.

The bill would guarantee confidentiality to healthcare providers who reported problems, and would bar the reports from being used in malpractice suits and workplace and professional disciplinary proceedings. It would not block patients and families from using other medical records as evidence in a lawsuit.

"When physicians can report errors in a voluntary and confidential manner, everyone benefits," Dr. J. Edward Hill, president of the American Medical Association, said following the House vote. "Future system errors can be avoided as we learn from past mistakes."

Under the bill, the Department of Health and Human Services would certify patient safety organizations to collect reports and analyze them for patterns of problems.

Analysts would try to pinpoint crucial initial events that prompted mistakes to cascade. The reports — minus details that could identify individuals and institutions — would be collected in a national database.

The safety organizations could be government agencies or private professional groups. Their analysts would be able to contact hospitals where a staff member had reported a problem and seek corrective action. The organizations could also put out safety alerts to the broader medical community.