Adverse drug events are unintended and harmful events related to medication use and a leading cause of emergency department visits, unplanned hospital admissions and deaths. In the emergency department, physicians frequently misdiagnose adverse drug events leading to treatment delays. Our objective is to evaluate the effect of pharmacist-led medication review in high-risk emergency department patients on prolonged hospital stay.

This prospective multi-centre, quasi-randomized study is nested within an existing quality improvement program. Triage nurses flag incoming emergency department patients at high-risk for adverse drug events by applying a clinical decision rule consisting of four variables (co-morbid conditions, antibiotic use within 7 days, medication changes within 28 days, and age). Consecutive eligible high-risk patients are enrolled into the medication review study, and systematically allocated to pharmacist-led medication review or usual care. In the intervention group, medication review pharmacists collect best-possible medication histories, review the patient's medications for appropriateness and adverse drug events, and communicate the results of medication review to patients, caregivers and physicians. In the usual care group, physicians refer patients to onsite pharmacists for medication management questions on an as needed basis. Health outcomes are assessed using anonymized data linkage to administrative health databases. The primary outcome is the percent of days spent in hospital during the first 30 days after the index emergency department visit

Inclusion Criteria:

Consecutive high-risk patients, aged 19 years or older, presenting to a participating emergency department when a medication review pharmacist is on duty are eligible for enrolment.

Exclusion Criteria:

We will exclude patients categorized as Canadian Triage Acuity Score (CTAS) 1 as they require immediate resuscitation, those presenting for multisystem trauma (e.g., penetrating trauma), scheduled visits (e.g., for intravenous antibiotics), sexual assaults, pregnancy-related complications, social problems, and those for whom we cannot link data to administrative records (e.g., out-of-province patients).