GVHD Prophylaxis and Incidence in Contemporary AlloHSCT: A Large Real-World GETH/TC Analysis.

Graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (alloHSCT). Although post-transplant cyclophosphamide (PTCy) and antithymocyte globulin (ATG) have reshaped prophylactic strategies, contemporary real-world data on GVHD incidence under current practice are limited. We conducted a nationwide retrospective study including 1 544 alloHSCTs performed in Spain (2018-2020) to characterize current prophylaxis patterns and the epidemiology of GVHD. PTCy-based prophylaxis was used in 65.6% of transplants, being nearly universal in haploidentical donors (96.9%) and predominant in mismatched unrelated (72.4%), matched unrelated (58.6%), and matched related donors (43.5%). The cumulative incidence of acute GVHD grades II-IV was 28.4% at day +100 and 30.7% at 1 year; grade III-IV occurred in 6.9% and 8.0%, respectively. Chronic GVHD at 2 years was 36.7%, with 23.5% moderate-to-severe cases. Acute GVHD was independently associated with inferior survival (HR 2.40, p<0.001), particularly grade III-IV disease (HR 4.34, p<0.001). These findings define the contemporary real-world burden of GVHD in a high-volume European country and provide an updated epidemiologic framework to inform preventive strategies, clinical trial design, and healthcare planning in modern alloHSCT.