Potentially avoidable medical errors account for about 1.5% of Medicare spending on inpatient hospital care, officials estimate.

Officials in the Office of the Inspector General at the U.S. Department of Health and Human Services discuss the cost of treating Medicare enrollees for adverse events in hospitals.

Inspector general office investigators defined “adverse event” as “harm to a patient as a result of medical care,” such as infection associated with use of a catheter. They looked at the files of 780 Medicare beneficiaries picked at random from all beneficiaries discharged during October 2008.

The investigators found that about 1% of the beneficiaries in the sample experienced a very serious adverse event and about 13% experienced a serious adverse event.

About 13% additional Medicare beneficiaries experienced adverse events that caused problems that were dealt with during their hospital stays, investigators found.

“Physician reviewers determined that 44% of adverse and temporary harm events were clearly or likely preventable,” officials say.

Another 51% were not preventable, and, in 5% of the cases, whether an event was preventable was not clear, officials say.

Based on the investigation results, adverse events of all kinds, including events that were not preventable, probably accounted for about $4.4 billion in Medicare spending in fiscal year 2009, or about 3.5% of Medicare expenditures on inpatient care, officials say.

“These Medicare cost estimates do not include additional costs required for followup care after the sample hospitalizations,” officials note.

- Allison Bell