Organ allocation and transplant equity in Brazil: the hidden burden of HLA homozygosity and hypersensitization

INTRODUCTION: Kidney transplantation remains the most cost-effective treatment for end-stage renal disease (ESRD); however, persistent organ scarcity and immunological barriers contribute to prolonged waiting times and inequitable access. Human leukocyte antigen (HLA) sensitization and homozygosity represent major challenges inadequately addressed by previous allocation models. OBJECTIVES: This study aimed to assess the impact of HLA sensitization and HLA homozygosity on access to kidney transplantation in the regional sector of Minas Gerais. METHODS: We conducted a cross-sectional analysis of deceased-donor kidney transplant recipients and active candidates listed in the Brazilian National Transplant System (SNT) from January 2010 to August 2024 in a regional allocation sector of Minas Gerais. We assessed the impact of HLA sensitization and HLA-DRB1 homozygosity on access to transplantation, contextualizing the findings within recent national regulatory updates. RESULTS: Of 2,907 patients analyzed, 1,794 (61.7%) underwent transplantation and 1,113 (38.3%) remained active on the waiting list. Diabetes mellitus (HR 1.177; p = 0.030) and blood groups A (HR 1.206; p < 0.001) and AB (HR 1.419; p = 0.002) were associated with increased access to transplantation. Higher levels of sensitization and HLA-DRB1 homozygosity were the strongest predictors of prolonged waiting time. These findings are consistent with inequities targeted by the Brazilian SNT regulatory revisions implemented in September 2025. CONCLUSION: Our results support recent Brazilian allocation reforms aimed at prioritizing hypersensitized and immunogenetically disadvantaged patients. Incorporating both the degree of sensitization and HLA-DR homozygosity into allocation algorithms represents a critical step toward improving equity in deceased-donor kidney transplantation.