Diagnostic Utility of Monocyte Distribution Width for Early Sepsis Detection in Cancer-Enriched Emergency Cohort

Background: Timely recognition of sepsis remains a critical clinical challenge, particularly in cancer patients, who are at higher risk due to immunosuppression. Monocyte distribution width (MDW) has emerged as a biomarker with potential utility in the early detection of sepsis. Methods: This retrospective study analyzed 1167 patients who presented to the emergency department of a cancer specialty hospital in Republic of Korea. Patients were classified according to Sepsis-2 and Sepsis-3 criteria, and the diagnostic performance of MDW was compared with conventional biomarkers, including C-reactive protein (CRP) and procalcitonin (PCT). Subgroup analyses were conducted based on malignancy status, leukopenia, and initial signs of infection. Additionally, turnaround times (TATs) were compared among the biomarkers. Results: MDW demonstrated diagnostic accuracy comparable to or exceeding that of CRP and PCT for identifying sepsis and infection across both Sepsis-2 and Sepsis-3 criteria. In the context of diagnosing sepsis using the Sepsis-3 criteria, MDW yielded the highest area under the curve (0.869), sensitivity (91.0%), and negative predictive value (98%). Notably, in cancer patients, MDW maintained strong diagnostic reliability. It also demonstrated high diagnostic capability in patients with leukopenia or presenting with initial signs of infection. Moreover, the TAT was significantly shorter for MDW (median 59 min) than for CRP (105 min) or PCT (111 min). Conclusions: MDW is a rapid and accessible biomarker with demonstrated value for early sepsis detection in emergency settings. Its balanced diagnostic profile and consistent performance across diverse patient subgroups support its integration into routine clinical workflows, especially as part of multimodal sepsis screening strategies.