Investigating the Effects of Pharmacist Involvement on Emergency Department Outcomes: A Retrospective Cohort Study.

Background: Pharmacists in emergency departments (EDs) have been shown to enhance patient care, yet their integration into ED teams remains inconsistent. Objectives: To determine whether involvement of an ED pharmacist influences patient flow in the ED (determined by length of the ED stay and return to the ED) and to describe the patient population seen by ED pharmacists. Methods: This retrospective cohort study included adults who visited EDs from April 1 to November 30, 2023, at 11 hospitals in Alberta but were not admitted to hospital. Patients seen by pharmacists were identified using the pharmacy's workload tracking system. Primary end points were ED length of stay (LOS) and a composite of return ED visit and death within 7 and 30 days. Results: Of the 183 182 qualifying ED visits, pharmacists were involved in 7441. Patients in the group seen by a pharmacist were older, used more medications, and had more comorbidities. Relative to a matched cohort without pharmacist involvement, patients seen by pharmacists had longer median LOS in the ED (7.7 vs 6.7 hours, Conclusions: Although previous literature has shown that pharmacists improve quality-of-care measures in the ED, the findings of the current study suggest that ED pharmacists' services could be optimized further by targeting activities that reduce LOS and return visits. The study emphasizes the need for high-quality research on ED pharmacist practice to optimize clinical pharmacy services in the ED.