Adverse drug events in adult patients leading to emergency department visits.

Background: Adverse drug events (ADEs) occurring in the community and treated in emergency departments (EDs) have not been well studied.

Objective: To determine the prevalence, severity, and preventability of ADEs in patients presenting at EDs in 2 university-affiliated tertiary care hospitals in the Canadian province of Newfoundland and Labrador.

Methods: A retrospective chart review was conducted on a stratified random sample (n = 1458) of adults (> or =18 y) who presented to EDs from January 1 to December 31, 2005. Prior to the chart review, the sample frame was developed by first eliminating visits that were clearly not the result of an ADE. The ED summary of each patient was initially reviewed by 2 trained reviewers in order to identify probable ADEs. All eligible charts were subsequently reviewed by a clinical team, consisting of 2 pharmacists and 2 ED physicians, to identify ADEs and determine their severity and preventability.

Results: Of the 1458 patients presenting to the 2 EDs, 55 were determined to have an ADE or a possible ADE (PADE). After a sample-weight adjustment, the prevalence of ADEs/PADEs was found to be 2.4%. Prevalence increased with age (0.7%, 18-44 y; 1.9%, 45-64 y; 7.8%, > or =65 y) and the mean age for patients with ADEs was higher than for those with no ADEs (69.9 vs 63.8 y; p < 0.01). A higher number of comorbidities and medications was associated with drug-related visits. Approximately 29% of the ADEs/PADEs identified were considered to be preventable, with 42% requiring hospitalization. Cardiovascular agents (37.4%) were the most common drug class associated with ADEs/PADEs.

Conclusions: Adult ADE-related ED visits are frequent in Newfoundland and Labrador, and in many cases are preventable. Further efforts are needed to reduce the occurrence of preventable ADEs leading to ED visits.