Improving Access to Transplantation and Outcomes for African American Patients
University of Toledo, Toledo, OH
Meeting: 2020 American Transplant Congress
Abstract number: A-291
Keywords: African-American, HLA matching, Kidney transplantation, Survival
Session Information
Session Name: Poster Session A: Histocompatibility and Immunogenetics
Session Type: Poster Session
Date: Saturday, May 30, 2020
Session Time: 3:15pm-4:00pm
Presentation Time: 3:30pm-4:00pm
Location: Virtual
*Purpose: Black or African American patients are clearly disadvantaged in comparison to Caucasian patients both in terms of the access to kidney transplantation and post-transplant kidney graft survival. We hypothesized that improved graft survival may be achieved by lowering immunogenicity based on HLA physiochemical properties.
*Methods: We calculated the hydrophobic mismatch score (HMS) of HLA-A/B/DR as the sum of hydrophobic charges for HLA polymorphic amino acids different between a donor and a recipient (by Cambridge algorithm). The 2-digit HLA-A/B/DR of 64,053 Black and Caucasian deceased donor/recipient pairs (obtained from the SRTR; 2000-2016) were imputed into 4-digit and then their HMS values were calculated. Both Kaplan-Meier survival estimates and multiple Cox regression modeling were used to evaluate the impact of immunogenicity and race on kidney allograft survival.
*Results: When all matched donor/recipient pairs were analyzed (0-HLA mismatch; MM), black recipients constituted 10.9% and Caucasian 89.1% of 0-HLA mismatched transplants. In contrast, 56.1% black and 43.9% white recipients had 6-HLA mismatched transplants. Overall, the median death-censored allograft survival in Blacks was 5 years shorter than in Caucasians (10.5 and 15.6 years, respectively; p<0.0001; Table 1). Only perfectly matched (HMS=0) black recipients treated with ATG induction had graft survivals of 15.4 years, similar to the survival outcomes as all unadjusted Caucasian recipients of 15.6 years (p=NS). The best Caucasian matches (HMS=0) with ATG induction therapy had graft survival of 19.3 years. Adjustments by multivariate Cox method of HLA immunogenicity with other confounders produced the same results (not shown).
*Conclusions: Black recipients receive kidney transplants with significantly higher HLA immunogenicity than white recipients. One strategy to improve outcomes for black recipients could be to prioritize black patients with lower immunogenicity donors as determined by HMS.
| Recipient Race | Donor Race | Median Survival (years) | Low 95% CI limit | High 95% CI limit |
| Black | All | 10.5 | 10.2 | 10.7 |
| Black | Black donor | 9.9 | 9.4 | 10.5 |
| Black HMS=0 | Caucasian donor | 10.7 | 10.4 | 11.1 |
| Black HMS=0 + ATG | All | 13.8 | 10.8 | NA |
| Black MM=0 | All | 15.4 | 9.3 | NA |
| Black MM=0 No ATG | All | 10.3 | 2.9 | 10.3 |
| Black MM=0 + ATG | All | 13.1 | 9.5 | NA |
| Recipient Race | Donor Race | Median Survival (years) | Low 95% CI limit | High 95% CI limit |
| Caucasian | All | 15.6 | 15.1 | 16.1 |
| Caucasian | Caucasian donor | 15.8 | 15.3 | 16.1 |
| Caucasian | Black donor | 14.6 | 12.0 | NA |
| Caucasian HMS=0 | All | 19.3 | 15.1 | NA |
To cite this abstract in AMA style:
Bekbolsynov D, Ekwenna O, Mierzejewska B, Borucka J, Khuder SA, Rees M, Green R, Stepkowski S. Improving Access to Transplantation and Outcomes for African American Patients [abstract]. Am J Transplant. 2020; 20 (suppl 3). https://atcmeetingabstracts.com/abstract/improving-access-to-transplantation-and-outcomes-for-african-american-patients/. Accessed May 9, 2025.« Back to 2020 American Transplant Congress