Using computers to prescribe drugs has helped doctors curb dangerous errors caused by messy handwriting and bureaucratic mishaps, but the technology can create its share of mistakes, a study said on Tuesday.

In some cases, fragmented computer displays result in prescription errors, or drug inventory information from the pharmacy has been mistaken for dosage guidelines.

In other cases, doctors’ orders to renew a drug were placed on paper charts but not on the computer system, drugs were incorrectly ordered more than once, incompatible drugs were ordered simultaneously, or the computer system’s inflexibility generated its own mistakes.

“The literature on (Computer Physician Order Entry systems), with few exceptions, is enthusiastic. Our findings, however, reveal that CPOE systems can facilitate error risks in addition to reducing them,” wrote chief study author Ross Koppel of the University of Pennsylvania School of Medicine, Philadelphia.

Noting that 770,000 U.S. patients are killed or injured annually by so-called adverse drug events, the report said previous research had shown computer entry systems had sharply reduced medication errors. But it concluded the technology needed constant attention and continuous revisions.

“This limitation is especially noteworthy because many problems we identified are easily corrected,” he wrote in a report published in the Journal of the American Medical Association.

Koppel and his colleagues interviewed a 261-person hospital staff using a computer ordering system, discovering 22 types of medication errors that were experienced by three-quarters of those surveyed.

An accompanying editorial in the same journal said the findings were disappointing but not surprising.

“Clearly, there is no reason to expect health care, which is from an organizational standpoint probably the most complex enterprise in modern society, to be immune to (problems),” wrote Robert Wears of the University of Florida, Jacksonville, and Marc Berg, of Erasmus University, Rotterdam, the Netherlands.

“Since roughly 75 percent of all large (information technology) projects in health care fail, inattention to these lessons is, at best, wasteful of time and resources and, at worst, harmful to patients and clinicians,” they wrote.