Prospective Validation of Clinical Criteria to Identify Emergency Department Patients at High Risk for Adverse Drug Events

Objectives Adverse drug events (ADEs) cause or contribute to one in nine emergency department (ED) presentations in North America and are often misdiagnosed. EDs have insufficient clinical pharmacists to complete medication reviews in all incoming patients, even though pharmacist‐led medications reviews have been associated with improved health outcomes. Our objective was to validate clinical decision rules to identify patients presenting with ADEs so they could be prioritized for pharmacist‐led medication review. Methods This multicenter, prospective study was conducted in two tertiary and one community hospital in Canada. We enrolled 1,529 adults presenting to EDs over 12 months. We applied two clinical decision rules and collected baseline variables prior to assessments by clinical pharmacists and physicians. We compared the physician and pharmacist diagnoses with the decision rule results. The primary outcome was a moderate or severe ADE, defined as an unintended and harmful event related to medication use or misuse, which required a change in medical therapy, diagnostic testing, consultation, or admission. An independent committee adjudicated uncertain and discordant cases. We calculated the diagnostic accuracy of both rules. Results Among 1,529 patients, 184 (12.0%) were diagnosed with an ADE. Rule 1 contained the variables 1) having a preexisting medical condition or having taken antibiotics within 1 week and 2) age > 80 years or having a medication change within 28 days. They had a sensitivity of 91.3% (95% confidence interval [CI] = 86.3%–95.0%) and a specificity of 37.9% (95% CI = 35.3%–40.6%) for ADEs. Conclusions Our study validated clinical decision rules that can be applied by clinical pharmacists to limit the number of patients requiring medication review, while identifying the majority of patients presenting with clinically significant ADEs.