AIMIn a randomized control trial mid-regional proadrenomedullin (MR-proADM)-guided decision-making has been proven to safely reduce hospital admissions based on an accurate assessment of disease severity in the Emergency Department (ED). This study aimed to assess the impact of a MR-proADM-Guided Triage (MR-GT) versus standard Hospital Triage (HT) on clinical and economic outcomes in ED patients with suspected infection in Spain, Italy, Germany, and the UK, using Patient-Level Data (PLD) from two observational studies.METHODSPLD was collected from patients enrolled at a Spanish hospital during two observational studies. Logistic regression was used to identify predictors of hospitalization. A patient-level simulation model was subsequently developed to evaluate the clinical and economic impact of MR-GT versus HT using results from the statistical analysis and country-specific cost data from the published literature. Probabilistic and deterministic sensitivity analyses were carried out.RESULTSFour hundred seventy-three patients were enrolled in this study. MR-proADM had the strongest association with hospital admission, followed by age and National Early Warning Score (NEWS). In the simulation model, MR-GT was associated with an overall reduction in hospitalization relative to HT, equal to 22.6 percentage points (40.9 vs. 63.5%). In addition, the use of MR-GT would reduce the total hospital cost per patient presenting to the ED with suspected infection by roughly 30%, with a mean cost saving per patient of €626, €1,484, €1,154, and £1,113 in Spain, Italy, Germany, and the UK, respectively. The robustness of these findings was confirmed by sensitivity analyses.LIMITATIONSThe statistical analyses were not performed on the same population simulated in the model. Clinical input parameters were assumed to be the same for all countries.CONCLUSIONSMR-proADM showed to be the main predictor of hospitalization. An MR-proADM decision algorithm provides cost savings in Spain, Italy, Germany, and the UK.