The prognostic value of eosinophil count in emergency department cardiac arrest patients

Aim: Cardiac arrest remains a major cause of mortality despite advances in resuscitation techniques. Identifying early prognostic markers is crucial for optimizing patient management in the emergency department (ED). Eosinophil count, a simple and widely available hematological parameter, has been investigated as a prognostic marker in various critical conditions. However, its role in cardiac arrest patients remains unclear. This study aims to evaluate the prognostic value of eosinophil count in cardiac arrest patients and its association with the return of spontaneous circulation (ROSC). Methods: This retrospective observational study included 322 patients who experienced cardiac arrest either upon arrival at the ED or during their ED follow-up. Demographic characteristics, complete blood count parameters, and blood gas measurements were recorded. Patients were categorized into ROSC-positive (n=294) and ROSC-negative (n=28) groups. Logistic regression and receiver operating characteristic (ROC) analyses were performed to assess the predictive value of eosinophil count and other parameters. Results: Patients who did not achieve ROSC had significantly higher eosinophil counts than those who survived (median: 0.025 vs. 0.01, p=0.045). Additionally, low bicarbonate, low pH, and high lactate levels were strongly associated with mortality (p<0.001). ROC analysis showed that eosinophil count had moderate predictive value, while lactate and bicarbonate demonstrated better discrimination. Conclusion: Eosinophil count was significantly higher in non-survivors, suggesting a potential association with mortality in cardiac arrest patients. Given its rapid availability, eosinophil count may serve as an additional prognostic marker in the ED. However, further large-scale prospective studies are needed to validate its clinical utility. How to cite this article: Turan ÖF, Gedikaslan Ş. The prognostic value of eosinophil count in emergency department cardiac arrest patients. J Med Dent Invest 2025;6:e250173.