Medication errors common in outpatients with cancer

NEW YORK (Reuters Health) - Medication errors among patients being treated for cancer are increasing as care shifts from the hospital to the outpatient setting, according to research published online on December 29, 2008, in the Journal of Clinical Oncology.

"Outpatient chemotherapy regimens are particularly complex because of the intense monitoring required, unanticipated and frequent changes in medication doses based on clinical changes, body-surface area-based dosing calculations, and medications taken only on certain days of the week or month," lead investigator Dr. Kathleen E. Walsh, at the University of Massachusetts Medical Center in Worcester, and co-authors explain.

To determine how often and why errors occur, Dr. Walsh's team reviewed medical records at four outpatient oncology clinics for visits between September 2005 and May 2006. The data covered 1379 clinic visits and 11,908 prescribed medications.

Among adult patients, they identified 90 medication errors, at a rate of 7.1 per 100 visits. Fifty-five errors were potentially injurious, including 11 errors that did result in injury. The authors note that zoledronic acid and leuprolide were the drugs most commonly involved.

There were 117 pediatric patient visits involving 913 medications. Of 22 medication errors (18.8 errors per 100 visits), 9 could have caused injury, and four actual injuries occurred. Dapsone and cyproheptadine were most often associated with errors.

The authors note that 7% of errors among adult patients were in home administration, versus 27% of those among pediatric patients.

One problem was confusion over two sets of orders -- one written at diagnosis and another adjusted dose on the day of administration -- with medication administered from the wrong set of orders. "Requiring that medication orders not be written until the day of administration, following review of laboratory results," may reduce errors, the authors suggest.

Other strategies to reduce errors among adult patients were improved communication and bar coding.

For pediatric patients, Dr. Walsh and associates recommend "drug dose double-checking, improved communication, and patient education about home medication use."

Although these rates are higher than previously reported, the investigators note that the estimates are likely to be conservative since they rely solely on medical record review.

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