Hospital rec-ords often err in listing medications that patients older than 65 were taking before admission, posing a risk of serious treatment errors, a study suggests.

Sixty percent of records in the study contained at least one error in listing "important" medications, and 18 percent had three or more errors.The analysis excluded over-the-counter drugs, cold medicines and medications applied to the body. When those drugs were included, 83 percent of hospital records contained at least one error.

Mistakes in medication records mean patients may not be given drugs they need, or they may get unneeded drugs that cause harmful side effects, Dr. Mark Beers said.

He cited the case of a patient whose records failed to note she was taking an oral diabetes medication. The drug was not continued in the hospital until Beers pointed out the error, he said.

Another patient was given a blood-thinning drug because his record said he was on the medication, when in fact the treatment had been stopped months before, Beers said. The error created a needless risk of bleeding, Beers said.

"We found some really clinically very important problems" that could lead to complications, prolonged hospital stays and perhaps even death, Beers said.

The study appears in the November issue of the Journal of the American Geriatrics Society.