Early eosinophilia after hematopoietic stem cell transplantation is associated with chronic graft‐versus‐host disease

Abstract Background This study aimed to evaluate whether an early elevation of absolute eosinophil count after allogeneic hematopoietic stem cell transplantation (allo‐HSCT) was associated with the development of chronic graft‐versus‐host disease (cGVHD) in children and adolescents. Methods A total of 165 consecutive patients who received allo‐HSCT were included in the study. Patients who had previously received allo‐HSCT, relapsed or died before Day 100, and did not achieve engraftment, were excluded. Eosinophilia was defined as an eosinophil count exceeding 500/μL in peripheral blood within 60 days of stem cell infusion. Results Eosinophilia was observed in 67 patients (40.6%). There were no significant differences in disease type, graft source, donor type, conditioning regimen, and GVHD prophylaxis and treatment between the patients with or without eosinophilia. The 3‐year cumulative incidence rate of cGVHD in the entire cohort was 39.3% (95% confidence interval (CI): 32.2–47.4). Patients with eosinophilia had a higher 3‐year cumulative incidence rate of cGVHD compared to those without eosinophilia (49.1% vs. 32.7%, p = 0.007). Cox proportional hazards model analysis revealed that eosinophilia was associated with an increased risk of cGVHD (adjusted hazard ratio: 2.12; 95% CI: 1.16–3.85, p = 0.014). Conclusions Early eosinophilia after allo‐HSCT may serve as a predictor for the development of cGVHD in children and adolescents.