Philadelphia ? Computerized prescription-ordering systems are promoted as the answer to preventing medication errors in hospitals, but a new study shows the technology also can cause mistakes.

The study at the Hospital of the University of Pennsylvania found that computer systems that allowed doctors to order drugs electronically, rather than writing orders, could lead to a variety of errors, including ordering drugs for the wrong patient or at an incorrect dosage.

“What is supposed to be the great solution is itself a source of errors,” said Ross Koppel, a Penn sociologist who led the study.

While computerized systems “do offer some real protection,” Koppel said, the study identified 22 types of medication errors that could result.

The study, published in Wednesday’s Journal of the American Medical Assn., comes as consumer advocates, corporate leaders and the Bush administration are urging a transition from paper records to electronic files to improve patient care.

The push for “computerized physician-order entry” systems was fueled in part by a 1999 report by the Institute of Medicine, which said medication errors killed about 7,000 in this country each year.

Studies have shown that computerized prescribing could eliminate upward of about 80 percent of medication errors, in part by avoiding mistakes caused by a doctor’s handwriting or transcribing a prescription incorrectly as it goes through the system.

More hospitals are getting on board with the technology. A survey of about 1,600 hospitals nationwide found that 10 percent had fully implemented computerized systems in 2004, and an additional 5 percent had prescribing systems used to varying degrees, according to the Institute for Safe Medication Practices.