Statistical Analysis

Categorical data were analyzed using a chi-square test. Survival analysis was conducted using the Kaplan-Meier method, and groups were compared using a log-rank test. The cumulative incidence of GVHD was calculated using the Gray method considering treatment-related mortality and relapse as competing risks. The Cox proportional regression model was used to analyze potential risk factors affecting survival. Statistical analyses were performed using the SPSS software version 18 (SPSS Inc., Chicago, IL, USA) and EZR (Saitama Medical Center, Jichi Medical University, Saitama, Japan)²⁰.