Donor-Recipient Size Mismatch and Rates of Graft Survival

New Orleans—Poorer kidney graft survival is associated with advanced donor age, recipient age, and donor-recipient size mismatch. However, there are few available data on the interaction among these variables. Researchers in Canada conducted a retrospective cohort study designed to examine those interactions. Fanny Lepeytre, MD, reported results of the study during a poster session at Kidney Week 2017 in a poster titled The Effect of Donor-Recipient Size Mismatch on Graft Survival Is Modified by Kidney Transplant Recipient and Donor Age.

The study utilized data from the Scientific Registry of Transplant Recipients on all first deceased kidney transplantation preformed between January 1, 2000, and January 1, 2015, on adults ≥18 years of age. The association between donor-recipient body surface area ratio (≤0.9 vs >0.9) and overall graft survival was assessed using multivariable Cox proportional hazards models. Overall graft survival was defined as death with function, return to dialysis, or retransplantation. The researchers examined the interaction between body surface area ratio and recipient age (≤54 vs >54 years of age) and donor age (≤60 vs >60 years of age), as well as the three-way interaction term of body surface area ratio by recipient age and donor age.

Over a median follow-up of 4.8 years, 33.3% of 118,101 patients (n=39,330) experienced graft loss. The three-way donor-recipient body surface area ratio by donor age by recipient age interaction was statistically significant (P=.02).

Among transplant recipients ≤54 years of age, there was an association between a donor-recipient body surface area ratio ≤0.9 and a higher risk of graft failure when donors were <60 years of age (hazard ratio [HR], 1.11; 95% confidence interval [CI],1.07-1.14); when the donor was >60 years of age, there was no association between donor-recipient body surface area ratio ≤0.9 and graft survival (HR, 0.92; 95% CI, 0.81-1.04).

In transplant recipients >54 years of age, there was a significant association between donor-recipient body surface area ratio ≤0.9 and graft failure, regardless of donor age (HRs, 1.07; 95% CI, 1.03-1.10 for donors ≤60 years of age and 1.09, 95% CI, 1.02-1.16 for donors >60 years of age).

“We find donor-recipient size mismatch to have a small but significant impact on graft survival in all but younger recipients of older deceased donors. We hypothesize that in the latter group, the adverse impact of donor age supersedes the effect of donor-recipient size mismatch, and a size mismatch should not be considered as adversely affecting graft survival in this patient population,” the researchers said.

Source: Lepeytre F, Delmas-Frenette C, Zhang X, Sapir-Pichhadze R, Foster BJ, Cardinal H. The effect of donor-recipient size mismatch on graft survival is modified by kidney transplant recipient and donor age. Abstract of a poster presented at the American Society of Nephrology Kidney Week 2017, November 3, 2017, New Orleans, Louisiana.