Objectives Sepsis is a time-dependent and life-threating condition. Despite several biomarkers are available, none of them is completely reliable for the diagnosis. This study aimed to evaluate the diagnostic utility of monocyte distribution width (MDW) to early detect sepsis in adult patients admitted in the Emergency Department (ED) with a five part differential analysis as part of the standard clinical practice. Methods A prospective cohort study was conducted on 985 patients aged from 18 to 96 and included in the study between November 2019 and December 2019. Enrolled subjects were classified into four groups based on sepsis-2 diagnostic criteria: control, Systemic Inflammatory Response Syndrome (SIRS), infection and sepsis. The hematology analyzer DxH 900 (Beckman Coulter Inc.) provides the new reportable parameter MDW, included in the leukocyte 5 part differential analysis, cleared by Food and Drug administration (FDA) and European Community In-Vitro-Diagnostic Medical Device (CE IVD) marked as early sepsis indicator (ESId). Results MDW was able to differentiate the sepsis group from all other groups with Area Under the Curve (AUC) of 0.849, sensitivity of 87.3% and specificity of 71.7% at cut-off of 20.1. MDW in combination with white blood cell (WBC) improves the performance for sepsis detection with a sensitivity increased up to 96.8% when at least one of the two biomarkers are abnormal, and a specificity increased up to 94.6% when both biomarkers are abnormal. Conclusions MDW can predict sepsis increasing the clinical value of Leukocyte 5 Part Differential analysis and supporting the clinical decision making in sepsis management at the admission to the ED.
