TOP 40 - Monocyte distribution width as an early marker of pneumonia in children presenting to the Emergency Room with respiratory distress

Publication Number: 4743.TOP 40

Candace A. Callender, MassGeneral Hospital for Children, Somerville, MA, United States; Sergio Monares Ortiz, MassGeneral Hospital for Children, Everett, MA, United States; Cody Cross, Johns Hopkins University School of Medicine, Baltimore, MD, United States; Ama S.. Apenteng, Johns Hopkins University School of Medicine, Baltimore, MD, United States; Tyrus Vong, Johns Hopkins University School of Medicine, Baltimore, MD, United States; Daniel Irimia, Massachusetts General Hospital, Boston, MA, United States; Oluwakemi Badaki-Makun, Johns Hopkins University School of Medicine, Baltimore, MD, United States; Lael Yonker, UT Southwestern Medical Center, Boston, MA, United States

Background: Respiratory distress is one of the most common reasons for seeking urgent medical evaluation in children. Identifying pneumonia quickly is essential in preventing progression of infection and establishing appropriate treatment. However, distinguishing pneumonia from upper respiratory infection is challenging and often warrants radiographic imaging, which carries radiation risk and requires access to X-ray services. Monocyte anisocytosis dispersion quantified as monocyte distribution width (MDW) on a standard complete blood count (CBC) has shown diagnostic utility in systemic inflammatory states, including sepsis, severe COVID-19, and Multisystem Inflammatory Syndrome in Children. Its value in localized infections like pneumonia remains underexplored.

Objective: To determine whether an elevated MDW value is a useful screening tool for identifying pneumonia in children presenting to the Emergency Room with respiratory distress.

Design/Methods: We analyzed MDW from 1,395 leftover whole blood samples that were collected from children < 18 years of age upon presentation to the emergency room at either Mass General for Children or Johns Hopkins Children’s Center between 6/2022-6/2024 (MGB IRB protocol 2022P000415). Samples were analyzed on a UniCel DxH 900 hematology analyzer (Beckman Coulter, Inc., Brea, CA). Medical information was extracted from electronic medical records; children with respiratory symptoms were identified. Clinical diagnosis of pneumonia was established in those with and without radiographic consolidation/opacity confirmed by radiology report. Exclusion criteria included severe immunosuppression, hematologic malignancy, and missing clinical key variables. Pediatric Sequential Organ Failure Assessment (pSOFA) scores and Sepsis 2 criteria were assigned to each patient. Outcomes were analyzed by t-test or ANOVA. Receiver operating characteristic (ROC) curve assessed accuracy of MDW in identifying disease severity. Analysis is ongoing and will be completed by the end of January 2026.