Factors associated with emergency department discharge among patients triaged as resuscitation (CTAS level 1): a retrospective cross-sectional study

Emergency department (ED) crowding is exacerbated by over-triage, particularly when patients are assigned to the highest acuity category of the Canadian Triage and Acuity Scale (CTAS) based on symptom-anchored, safety-oriented criteria but ultimately do not require intensive resources. This study aimed to identify triage-time characteristics associated with ED discharge among patients triaged as CTAS level 1 (“Resuscitation”). ED discharge was examined as a pragmatic signal of potential over-classification. We performed a retrospective cross-sectional study of consecutive adult patients (≥ 20 years) triaged as CTAS level 1 at a tertiary academic hospital in northern Thailand between October 2020 and October 2024. The primary outcome was ED disposition, classified as discharge versus non-discharge. Multivariable analysis was performed using Firth’s penalized logistic regression and was restricted to variables available at the time of triage, including demographics, arrival mode, vital signs, and presenting complaint categories. Of 13,708 CTAS level 1 encounters, 5,498 met the inclusion criteria; 440 patients (8%) were discharged. Factors independently associated with lower odds of ED discharge included arrival by emergency medical services (adjusted odds ratio [aOR] 0.60, 95% CI 0.45–0.79), age > 65 years (aOR 0.79, 95% CI 0.62–0.98), respiratory rate > 30 breaths/min (aOR 0.68, 95% CI 0.53–0.87), shock index > 0.9 at presentation (aOR 0.56, 95% CI 0.42–0.75), and hyperthermia > 39 °C (aOR 0.40, 95% CI 0.21–0.76). In contrast, presenting complaints independently associated with higher odds of discharge included allergic reactions (aOR 23.42, 95% CI 5.59–98.06), flank pain/urinary retention (aOR 11.45, 95% CI 2.24–58.48), leg edema (aOR 10.59, 95% CI 1.66–67.63), syncope (aOR 5.36, 95% CI 1.81–15.88), and substance intoxication (aOR 5.10, 95% CI 1.09–23.82). A measurable proportion of CTAS level 1 patients were discharged, with discharges concentrated in a limited set of triage-identifiable presenting complaints that often resolved after initial management. These findings do not indicate triage error but highlight situations in which safety-oriented high-acuity triage may coexist with favorable short-term ED outcomes. Further multicenter studies incorporating post-discharge outcomes are needed to confirm these associations.