High- and Low-Complexity Features of Non-Critical Adult Patients in the Emergency Department

<b>Background/Objectives</b>: In the Emergency Department (ED), non-critical patients are classified as Triage Level (TL) 3 on arrival if they are assessed as having a high-level of complexity (HLC), or as TL4-5 if they are assessed as having a low-to-mild level of complexity (LLC). These levels are based on the estimated resources needed. This study aimed to identify the characteristics associated with an HLC or LLC by considering a group of variables from the presentation profile (PP) and clinical diagnostic workload (CDW), assessing ex post whether the assignment of complexity levels based on a priori estimation of the number of resources needed can be considered adequate. <b>Materials and Methods</b>: This retrospective multicentre study involved four first-level EDs and included patients between 2023 and 2024. <b>Outcome Measures</b>: The variables tested in a logistic model were those of the PP (age, sex, chief complaint, National Early Warning Score (NEWS), Numeric Rating Scale (NRS) and those of the CDW (diagnostic tests, interventions and therapy, assistance, and ED length of stay). <b>Results</b>: Of the 335,507 subjects considered, the average age was 59 years (interquartile range [IQR], 25), with 43.3% of cases classified as TL3. An NRS ≥ 7, ECG, urgent laboratory tests, NEWS > 6, need for a stretcher, and male gender were associated with TL3, whereas obstetric-gynaecological complaints, environmental complaints, skin-presenting complaints, and intramuscular therapy were associated with TL4-5. <b>Conclusions</b>: In non-critical patients a defined group of features were associated with different levels of complexity, going beyond the standard criterion based on the resources needed. These results could help clinicians improve the appropriateness of ED care pathways.