Eosinophil-Platelet Ratio as a Predictive Marker of the Postoperative Recurrence of a Chronic Subdural Hematoma

BACKGROUND AND OBJECTIVES: Symptomatic chronic subdural hematoma (CSDH) is caused by repetitive hemorrhage and inflammation, which is commonly treated with burr-hole surgery and has a relatively high postoperative recurrence rate. A decrease in the platelet count is indicative of a hemorrhagic tendency, while an increase in the eosinophil count is associated with inflammation. Assessing the balance between platelet-associated hemostasis and eosinophil-associated inflammation using the indeterminate biomarker, the eosinophil-platelet ratio (EPR), may be essential. Therefore, in this study, the accuracy of the EPR in predicting postoperative CSDH recurrence was evaluated and their correlation was determined. METHODS: Data on symptomatic CSDHs of the cerebral hemisphere of patients who underwent burr-hole surgery at our institution between January 2013 and December 2022 were retrospectively reviewed. The EPR was calculated from preoperative peripheral blood examination data, and its correlation with postoperative CSDH recurrence was assessed. The hemispheres with CSDH were categorized into recurrence and nonrecurrence cohorts. RESULTS: Data from 459 cerebral hemispheres of 405 patients with symptomatic CSDH were analyzed. In the 459 cerebral hemispheres with CSDH, 39 (8.5%) had postoperative recurrence. CSDH patients with a high EPR (≥1 × 10 −3 ) had a significantly higher recurrent rate than those with a low EPR (<1 × 10 −3 ) (15 of 86 [17.4%] vs 24 of 373 [6.4%], P = .002). In the modified Poisson regression analysis, the crude and adjusted risk ratios of high EPR were 2.79 (95% CI: 1.53, 5.09) and 2.62 (95% CI: 1.40, 4.89), respectively. CONCLUSION: This study reveals that a high EPR is a useful predictive biomarker for postoperative CSDH recurrence. Cases of CSDH with a high EPR potentially require careful and close postoperative follow-up.