The Neutrophil/Lymphocyte Ratio is an Independent Predictor of All-Cause Mortality in Patients with Idiopathic Hypereosinophilic Syndrome

BACKGROUND: Idiopathic hypereosinophilic syndrome (IHES) often causes inflammatory damage to multiple organs. However, whether immune/inflammatory indicators and other factors are associated with mortality in patients with IHES remains unclear. PATIENTS AND METHODS: The clinical data and follow-up results of 167 patients with IHES were retrospectively analyzed using Cox regression analysis and receiver operating characteristic curve (ROC). RESULTS: Of 167 patients, 120 were men (71.9%) and 47 were women (28.1%). The median age was 52 (36.0, 68.0) years. The median follow-up period was 42.8 (18.5, 75.1) months, during which all-cause mortality occurred in 26 patients (15.6%). Age (HR: 1.041, 95% CI: 1.015–1.068; p = 0.002), lymphocyte counts (10(9)/L, HR: 0.866, 95% CI: 0.816–0.907; p = 0.013), platelet counts (10(9)/L, HR: 0.994, 95% CI: 0.989–0.999; p = 0.012) and NLR (HR: 1.161, 95% CI: 1.054–1.280; p = 0.003) were independent risk factors for all-cause mortality. There was no relationship between PLR, and SII and all-cause mortality (p = 0.181 and 0.202, respectively). ROC analysis showed that the AUCs of age, lymphocyte count (10(9)/L), platelet count (10(9)/L) and NLR were 0.712 (95% CI: 0.601–0.824), 0.584 (95% CI: 0.448–0.719), 0.686 (95% CI: 0.560–0.812), and 0.797 (95% CI: 0.695–0.899), respectively, with sensitivities of 0.5, 0.462, 0.769, and 0.792, respectively, and specificities of 0.765, 0.745, 0.617, and 0.845, respectively. Kaplan–Meier analysis (Log rank test) showed that patients with age ≥73.5 years, lymphocyte count (10(9)/L) <1.45, platelet count (10(9)/L) <225 and NLR ≥2.54 had high mortality. Patients with high NLR (≥2.54) usually have multiorgan involvement, with cardiac involvement and skin involvement being the most common. Patients with NLR ≥2.54 had significantly higher absolute eosinophil counts (p = 0.047) and percentages (p = 0.041). CONCLUSION: We identified NLR for the first time as an independent predictive factor for all-cause mortality in patients with IHES, necessitating its further application in clinical practice.