Monocyte Anisocytosis Can Discriminate Between Sepsis and Sterile Inflammation, but not Mortality, in Critically Ill Surgical/Trauma Patients: A Secondary Prospective Analysis.

Abstract

Objectives background: Monocyte anisocytosis (monocyte distribution width [MDW]) has been previously validated to predict sepsis and outcome in patients presenting in the emergency department and mixed-population ICUs. Determining sepsis in a critically ill surgical/trauma population is often difficult due to concomitant inflammation and stress. We examined whether MDW could identify sepsis among patients admitted to a surgical/trauma ICU and predict clinical outcome.

Design: Secondary analysis of three prospective observational clinical studies.

Setting: Single institution ICU.

Patients/subjects: Two hundred thirty-eight participants were included in this study: 107 patients who were admitted to the ICU and adjudicated to have sepsis, 80 patients who were considered critically ill nonseptic (CINS), and 51 healthy control participants.

Interventions: MDW was measured among hospitalized patients admitted to the ICU with the diagnosis of sepsis or CINS patients at risk of developing sepsis. Blood samples were collected at admission and at intervals during ICU admission.

Measurements and main results: MDW significantly differed between septic and CINS patients on ICU admission (26.4, interquartile range [IQR, 23.5-30.8] vs. 20.1 [IQR, 17.9-21.9]; p < 0.001) and could discriminate with an area under the receiver operating characteristic curve of 0.85 (95% CI, 0.79-0.91; p < 0.001). An MDW of greater than 22.0 at admission to the ICU could identify sepsis with a 78% specificity and a 90% sensitivity but could not discriminate in-hospital, 30-day, or 90-day mortality.

Limitations: Small sample size from a single institution. Our analysis did not include other relevant biomarkers such as procalcitonin, C-reactive protein, and interleukin-6. In the imputation of missing values, linear mixed-effect models were used, risking model misspecification and the violation of the missing-at-random assumption.

Conclusions: Among surgical/trauma ICU patients, MDW can discriminate between sepsis and nonseptic inflammation, but it is a weak predictor of mortality.