Association Between Emergency Department Undertriage or Overtriage With Timeliness of Care and Patient Outcomes

Assess how emergency department (ED) mistriage is associated with timeliness of ED care and patient outcomes.

This was a retrospective cohort study of ED encounters from 2016 to 2020, across 21 EDs. Using operational measures of triage accuracy, we assessed how assigned Emergency Severity Index (ESI) matched downstream intensity of care and resource use. Patients with a mismatch between ESI assignment and downstream resource use were classified as undertriaged high-acuity or overtriaged low acuity, whereas those with no mismatch were classified as true low-, mid-, or high-acuity. The primary outcome was delay in care; secondary outcomes included ED length of stay, intensive care unit admission (ICU), and short-term mortality.

Among 5,315,081 adult ED encounters, mean age was 51.7 years, 2,962,827 (56%) were women, and 590,566 (11.1%), 800,966 (15.1%), 2,336,012 (44.0%), 1,137,444 (21.4%), and 450,093 (8.5%) were Asian, Black, Non-Hispanic White, Hispanic, and other, unknown or multi-race, respectively. Undertriaged high-acuity patients had higher comorbidity burdens, high-risk medication use, and recent health care use compared with true mid- and high-acuity patients. In adjusted analyses, mistriage, both under- and overtriage, was associated with small delays in care. Undertriaged high-acuity patients had an 8-minute delay in care compared with true high-acuity patients. Overtriaged low-acuity patients had a 3-minute delay in care and a 42-minute longer total ED length of stay compared with true low-acuity patients.

Mistriage was associated with small delays in care. Early identification of critically ill patients remains a triage priority, and the use of patient history data may help support accurate triage.