Incidence and risk of potential adverse drug interactions in the emergencyroom

Objective: To determine the incidence and risk factors of potential adverse drug interactions occurring in patients in the emergency department. Desig n: Survey of a random sample of medical records of elderly persons and othe r adults seeking care at an emergency department. The interactions were det ermined by a computer programme, reviewed using explicit criteria, and excl uded if of uncertain or trivial clinical significance. Setting: University Hospital Medical Emergency Department. Patients: A total of 423 randomly se lected adults seeking care at a university hospital emergency department. A ttendances made by 195 persons over age 60 and 228 younger adults were eval uated. All subjects were treated on an outpatient basis. Main outcome measu res: Seventy percent of attendances led to the prescription of an added med ication. In 5.4% of the attendances in which at least one medication was ad ded, the new medication introduced a potential adverse interaction. The num ber of medications used at attendance was the best predictor of whether a p otential interaction would occur. Additional medications prescribed in the emergency department that accounted for most of the added interactions were theophylline, macrolid antibiotics, digitalis glycosides, nonsteroidal ant i-inflammatory agents, angiotensin converting-enzyme inhibitors and calcium antagonists. Conclusions: Potential adverse drug interactions were more co mmon in elderly patients because of the higher number of concurrent medicat ions rather than age-based factors. Safeguards need to be introduced to pre vent patients from receiving medications in the emergency departments that have the potential to cause adverse interactions. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.