Prevalence and clinical outcomes of eosinophilia in critically ill patients

Background. Eosinophilia in hospitalized patients is associated with increased mortality. However, eosinophilia was poorly investigated in the intensive care unit (ICU). The aim of our study was to investigate the prevalence of eosinophilia and its association with clinical outcomes in critically ill patients. Methods. This retrospective cohort study analyzed data from the Russian Intensive Care Dataset. The primary endpoint was the prevalence of eosinophilia (>0.5 x 10⁹/L) in ICU patients. The secondary endpoints included all-cause hospital mortality, mechanical ventilation and vasoactive drug use. Subgroup analysis was performed for patients with mild eosinophilia (0.5-1.5 x 10⁹/L) and hypereosinophilia (>1.5 x 10⁹/L). Results. Among the 2,082 patients included in the analysis, 406 (19%) developed eosinophilia during ICU stay, including 362 (17%) with mild eosinophilia and 44 (2%) with hypereosinophilia. Out of 2,082 patients, 1,676 (81%) did not develop eosinophilia, and 406 (19%) developed eosinophilia during ICU stay. Compared with patients without eosinophilia, patients in the eosinophilia group had longer hospital stay (41 [24-63] versus 32 [22-48] p < 0.001) and more frequently required mechanical ventilation (236 [58.1%] versus 722 [43.1%], p < 0.001) and vasoactive drugs (83 [24.6%] versus 226 [17.0%], p < 0.001). Mortality was higher in hypereosinophilia group compared with patients without eosinophilia (13 [29.5%] versus 201 [12%], p < 0.001). Conclusions. Patients with eosinophilia had longer hospital stays, increased requirement of mechanical ventilation and vasopressor support compared with patients without eosinophilia. Eosinophilia could represent a disease severity marker.