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Electronic medication alerts reduce inappropriate prescribing of warfarin with interacting drugs

Combining certain medications with the anticoagulant drug warfarin can have serious consequences. Medication interactions that accentuate warfarin's anticoagulant effect increase the risk for brain hemorrhage, other bleeding episodes, and death. Using electronic medical record alerts reduces the frequency of prescribing interacting drugs to patients who are also taking warfarin. This study was supported in part by the Agency for Healthcare Research and Quality (HS11843) through its Centers for Education and Research on Therapeutics and Patient Safety research programs.

Whenever a doctor in 1 of 15 primary care clinics involved in the study prescribed any potentially interacting medications—acetaminophen, non-steroidal anti-inflammatory drugs, fluconazole, metronidazole, or sulfamethoxasole—to a patient taking warfarin, an alert on the computer screen would tell the doctor the potential adverse outcome and suggest an alternative medication. Although these five drugs can accentuate warfarin's blood thinning effect, they were not contraindicated in all situations. The alerts, which were produced by software added to the health care organization's existing computerized prescription system, gave the physician the option of prescribing a different drug or overriding the alert.

At the start of the study, doctors were ordering 3,294 interacting drugs for every 10,000 warfarin patients. At the end of the study, the rate had dropped to 2,804 per every 10,000 warfarin patients—a reduction of 15 percent.

More details are in "Reducing warfarin medication interaction: An interrupted time series evaluation," by Adrienne C. Feldstein, M.D., David H. Smith, R.Ph., M.H.A., Ph.D., Nancy Perrin, Ph.D., and others, in the May 8, 2006, Archives of Internal Medicine 166, pp. 1009-1015.

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