Eosinopenia, an early marker of increased mortality in critically ill medical patients

Inflammatory markers may have a role in predicting severity of illness of intensive care unit (ICU) patients. The aim of this study is to determine whether low eosinophil count can predict 28-day mortality in medical ICU.

A prospective study over a 4-month period. To evaluate the prognosis information provided by eosinophil count, we compared the variations in eosinophil count from ICU admission to seventh day between patients who survived and those who died. The best cutoff value was chosen using Younden's index for identification of patients with high risk of mortality. The patient outcome was 28-day mortality.

A total of 200 patients were eligible. Overall 28-day ICU mortality was 28% (n = 56). At ICU admission, the median eosinophil count was significantly different in survivors [30 cells/mm³; interquartile range (IQR), 0-100 cells/mm³] and nonsurvivors (0 cells/mm³; IQR, 0-30 cells/mm³; P = 0.004). Absolute eosinophil counts remained significantly lower in nonsurvivors from admission to seventh day. The 28-day mortality was significantly higher in patients with eosinopenia <40 cells/mm(3) (P = 0.011). Multivariate analysis by Cox model with time-dependent covariates demonstrated that eosinophil count <40 cells/mm(3) [hazard ratio (HR), 1.85; 95% confidence interval (CI), 1.01-3.42; P = 0.046], high Acute Physiology and Chronic Health Evaluation (APACHE) II score (HR, 1.08; 95% CI, 1.01-1.14; P = 0.014), high Sequential Organ Failure Assessment (SOFA) score (HR, 1.14; 95% CI, 1.03-1.25; P = 0.008), and use of mechanical ventilation (HR, 27.48; 95% CI, 12.12-62.28; P < 0.001) were independent predictors of 28-day all-cause mortality.

This study suggests the possibility to use eosinophil cell count at admission and during the first 7 days as a prognosis marker of mortality in medical ICU.