Monocyte Distribution Width Is Elevated in Patients With Sickle Cell Disease Regardless of Presenting Complaint

Monocyte Distribution Width (MDW), a measure of variability in circulating monocyte size, is a novel biomarker of sepsis but may also be elevated in inflammatory conditions. We sought to determine if MDW levels are elevated in patients presenting to the pediatric emergency department (PED) with sickle cell disease (SCD), a chronic inflammatory condition.

This was a secondary analysis of prospectively collected data from PED encounters of patients aged 0-21 years presenting to two tertiary care academic centers from April 2022 to July 2024. SCD patients were matched to non-SCD (NSCD) controls in a 1:2 ratio based on chief complaint (fever or pain), sex at birth, and age. Data were analyzed using STATA and Python. Descriptive statistics, Students t-tests, and tests of proportions were performed, as were multivariable linear regression models.

There were 68 SCD and 136 NSCD patient encounters. Fever accounted for 35.3% of visits and pain 64.7%. In 66.2% of visits, patients were female. Median age was 12.1 years (Interquartile Range [IQR] 8.6) for SCD patients and 13.2 years (IQR 8.9) for NSCD patients. Black patients accounted for 95.6% of SCD visits and 42.7% of NSCD visits. For SCD visits, 67.7% had hemoglobin SS disease, 17.7% hemoglobin SC, and 14.7% hemoglobin S-Beta thalassemia. Mean MDW was elevated in SCD patients compared to NSCD patients presenting with pain (22.5; 95% Confidence Interval [CI] 21.3-23.7 vs. 20.2; 95% CI 19.5-20.8), difference 2.4, 95%CI 1.2-3.6, p<0.001. Mean MDW was higher in SCD patients compared to NSCD patients presenting with fever (28.6; 95%CI 25.5-31.6 vs. 25.1; 95% CI 24.1-26.0), difference 3.5, 95%CI 1.0-6.0, p<0.01. In multivariable regressions adjusting for age and chief complaint, SCD remained independently associated with higher MDW values, with an adjusted increase of 2.8 units (p<0.05). Fever was strongly associated with higher MDW values compared to pain, and increasing age was associated with a modest decrease in MDW.

In this multicenter cohort, MDW values were higher in patients with SCD compared with NSCD patients presenting with similar chief complaints. This association persisted after adjustment for age and chief complaint, suggesting that SCD status is independently associated with elevated MDW values. These findings highlight the need for further studies to define appropriate MDW interpretation and cut-offs in this population.