The implications of donor-recipient size mismatch in renal transplantation.

ABSTRACT

INTRODUCTION: Transplanting kidneys small for recipient's size results in inferior graft function. Body surface area (BSA) is related to kidney size. We used the BSA index (BSAi) (Donor BSA/Recipient BSA) to assess whether the renal graft size is sufficient for the recipient. METHODS: We included 26,223 adult single kidney transplants (01/01/2007-31/12/2019) from the UK Transplant Registry. We divided renal transplants into groups BSAi ≤ 0.75, 0.75 < BSA ≤ 1, 1 < BSAi ≤ 1.25, BSAi > 1.25. We compared delayed graft function rates, primary non-function rates and graft survival among them. (Reference category BSAi ≤ 0.75). RESULTS: Cases with BSAi ≤ 0.75 had the highest delayed graft function rates in living-donor renal transplants (11.1%) (0.75 < BSAi ≤ 1 OR = 0.59, 95% CI = 0.32-1.1, p = 0.095, 1 < BSAi ≤ 1.25 OR = 0.46, 95% CI = 0.23-0.89, p = 0.022, BSAi > 1.25 OR = 0.32, 95% CI = 0.13-0.77, p = 0.011) and in renal transplants from donors after brain death (26.2%) (0.75 < BSAi ≤ 1 OR = 0.72, 95% CI = 0.55-0.96, p = 0.024, 1 < BSAi ≤ 1.25 OR = 0.62, 95% CI = 0.47-0.83, p = 0.001, BSAi > 1.25 OR = 0.65, 95% CI = 0.47-0.9, p = 0.01). There were no significant differences in renal transplants from donors after circulatory death regarding delayed graft function rates (~ 40% in all groups). Graft survival was similar among BSAi groups in renal transplants from living donors and donors after brain death. Renal transplants from donors after circulatory death with BSAi ≤ 0.75 had the shortest graft survival (0.75 < BSAi ≤ 1 HR = 0.55, 95% CI = 0.41-0.74, p < 0.001, 1 < BSAi ≤ 1.25 HR = 0.48, 95% CI = 0.35-0.66, p < 0.001, BSAi > 1.25 HR = 0.45, 95% CI = 0.31-0.66, p < 0.001). Ten-year graft survival rate was 58.4% for renal transplants from donors after circulatory death with BSAi ≤ 0.75. CONCLUSIONS: Delayed graft function risk is higher in renal transplants with BSAi ≤ 0.75 coming from living donors and donors after brain death. Graft survival is greatly reduced in renal transplants from donors after circulatory death with BSAi ≤ 0.75.