Suspected adverse drug events requiring emergency department visits or hospital admissions

To analyse the contribution of adverse drug events (ADEs) to the overall number of referrals or visits at an emergency department, to determine the proportion of more severe episodes requiring hospital admission and to characterize the different causes of drug-related visits or admissions. A 1-year prospective collection of data on visits performed at an emergency department. All visits, observed during 1 week every month, were analyzed in order to identify suspected ADEs. The effects of age and sex on the frequency of ADE-related visits and admissions were evaluated. All patients hospitalized because of an ADE were followed up in order to collect information about progress and outcome of the events, which were also assessed in terms of avoidability. Among the 5497 patients who visited the Emergency Department over 1 year, 235 (4.3%) experienced an ADE, 45 of these (19.1%) were subsequently hospitalized, among whom there were five deaths. Dose-related therapeutic failures were the main causes of drug-related admissions (55.6%), whereas adverse drug reactions caused the most frequent drug-related visits to the Emergency Department (63.8%). Although the frequency of drug-drug interactions leading to a visit to the Emergency Department was small (3.8%), this type of event was more severe, because most of these patients were hospitalized. No age/sex effect was observed in the proportion of ADE-related hospital admissions. Twenty-five (1.4% of the total admissions) of the 45 ADE-related admissions were evaluated as preventable, contributing by more than 61% of the overall length of hospital stay. The high proportion of drug therapeutic failures leading to an admission highlights the need for public education, particularly to prevent non-compliance.