Potential adverse drug interactions in the emergency room. An issue in the quality of care.

STUDY
OBJECTIVE: To determine how often emergency department physicians prescribe medications that can adversely interact with other medications that their patients are already taking, which patients are at highest risk for potential adverse reactions, and which medications most frequently lead to adverse interactions.
DESIGN: Survey of elderly persons and other adults seeking care at an emergency department. PATIENTS: Four-hundred twenty-four randomly selected adults seeking care at a university-affiliated hospital emergency department.
MEASUREMENTS AND MAIN RESULTS: We evaluated 424 randomly selected visits to a hospital emergency department made by 186 persons over age 65 and 238 younger adults; all of the subjects were discharged without hospital admission. Forty-seven percent of visits led to added medication, and in 10% of the visits in which at least one medication was added, a new medication added a potential adverse interaction. The interactions were determined by a computer program, were reviewed using explicit criteria, and were excluded if of uncertain or trivial clinical significance, rare, or not established for that specific drug. The number of medications used at presentation was the best predictor of whether a potential interaction would be introduced.
CONCLUSIONS: In the emergency departments studied, a medication history was recorded on every patient and was available to physicians, but physicians did not routinely screen for potential drug interactions. Further safeguards are needed to protect patients from receiving medications that could produce adverse interactions.