Detection of patients presenting with adverse drug events in the emergency department

Background: Adverse drug events (ADE) have been studied widely in hospitalised and emergency department (ED) patients. Less is known about the ED visits of drug-related injury in Taiwan. This study seeks to determine the incidence, risk and patient outcomes of ADE in an ED population. Methods: We conducted a prospective observational cohort study of patients 18 years and older presenting to the ED of an urban, tertiary medical centre. ED visits between 1 March 2009 and 28 February 2010 identified by investigators for suspected ADE were further assessed by using the Naranjo Adverse Drug Reaction probability scale. Outcomes (ED disposition, injury severity and preventability) and associated variables (triage, gender, drug category, number of drugs, Charlson comorbidity index score and ADE mechanism) were measured. Results: Of 58 569 ED visits, 452 patients (0.77%) had physician-documented ADE. 24% of patients with ADE were hospitalised with life-threatening conditions, with a mortality rate of 10.0%. The majority of ADE were considered preventable (73.4%), and the unintentional overdose was the most common cause. Cardiovascular agents accounted for the most ADE (25.8%) and consisted of 65.3% of ADE in patients aged 65 years and older. Risk factors for ADE-related hospitalisation were elderly age (odds ratio (OR) 1.9, 95% confidence interval (CI) 1.13.4), severity of ADE (OR 6.9, 95% CI 3.314.5) and higher Charlson comorbidity index scores (OR 3.4, 95% CI 2.05.7). Conclusion: ADE-related ED visits are not uncommon in Taiwan and many cases are preventable. ED-based surveillance may provide useful information for monitoring outpatient ADE.