Healthcare-Associated Infections Impact Mortality in Patients Admitted to the Acute Care Hospital from the Emergency Department

<b>Background/Objectives</b>: Prolonged stays in overcrowded emergency departments (EDs) may contribute to an increased risk of healthcare-associated infections (HAIs) and therefore mortality. Early identification of the risk profile of these patients could reduce both complications and adverse outcomes. The study aimed to verify whether the development of an HAI was associated with increased mortality. <b>Design, settings and participants</b>: This retrospective multicentre study involved all subjects who required urgent admission to an acute care hospital from the ED between 2023 and 2024. <b>Outcome measures:</b> A Cox proportional hazards model was used to test 30-day mortality. <b>Results:</b> Among the 20,234 patients considered for analysis, the mean age was 79 years (20) (median (IQR)), and a total of 1575 (7.8%) had died at 30 days. The main features selected for predicting mortality were in order of importance, diagnosis of neoplasm, older age, NEWS, diagnosis of infectious diseases, HAIs, diagnosis of respiratory diseases, CCI, priority level on arrival and male gender, yielding an accuracy of 0.804 ± 0.012. HAI occurrence was associated with a mortality risk ratio of 1.518 (95% confidence intervals (CI): 1.338-1.721; <i>p</i> < 0.001). The risk was higher for bloodstream infections (2.54; 2.12-3.06) and pneumonia (1.44; 1.20-1.73). <b>Conclusions</b>: The occurrence of HAIs was associated with an increased risk of mortality in patients admitted to acute care hospitals from the ED. This risk was particularly elevated in case of bloodstream infections and pneumonia.