Unidentified patients in the emergency department: a historical cohort study.

Objectives: To characterize unidentified patients presenting to a single, urban emergency department (ED) in Canada. We report their demographics, ED course, post-ED discharge outcomes, and mode of identification.

Methods: We performed a retrospective chart review using descriptive analyses to assess unidentified patients admitted to Royal University Hospital and St. Paul's Hospital EDs between May 1, 2018, and April 30, 2019, in Saskatoon, Saskatchewan, Canada. We assessed demographic data, clinical presentation, mode of identification, discharge information, and major clinical outcomes.

Results: Unidentified patients were disproportionately male (64.9%), and mostly presented as Canadian Triage and Acuity Scale (CTAS) 1 (41.6%) and CTAS 2 (44.2%). Most patients arrived via emergency medical services (80.7%). The most common presenting complaints were substance misuse (33.3%) and trauma (24.6%). The average ED length of stay was 8.7 h (SD 18.6). Many patients received an inpatient consult (58.8%), and 22.3% received support services (e.g., social work). The 30-day mortality of all patients was 13.2%. Of those patients who survived to ED discharge, common dispositions included: home (36.0%), police services (3.5%), or emergency shelters (3.5%). Four (3.5%) patients returned to the hospital unidentified within the study period, and 6.7% of patients discharged from the ED returned within 48 hours.

Conclusion: Unidentified patients are a high-needs demographic that present mostly with substance misuse or trauma. Repeat ED attendance, sometimes as unidentified patients again, calls for initiatives that facilitate prompt identification, better discharge planning, and linkage to social supports.