A Kidney Graft Survival Calculator that Accounts for Mismatches in Age, Sex, HLA, and Body Size

Abstract

Background and objectives: Outcomes for transplants from living unrelated donors are of particular interest in kidney paired donation (KPD) programs where exchanges can be arranged between incompatible donor-recipient pairs or chains created from nondirected/altruistic donors.

Design, setting, participants, & measurements: Using Scientific Registry of Transplant Recipients data, we analyzed 232,705 recipients of kidney-alone transplants from 1998 to 2012. Graft failure rates were estimated using Cox models for recipients of kidney transplants from living unrelated, living related, and deceased donors. Models were adjusted for year of transplant and donor and recipient characteristics, with particular attention to mismatches in age, sex, human leukocyte antigens (HLA), body size, and weight.

Results: The dependence of graft failure on increasing donor age was less pronounced for living-donor than for deceased-donor transplants. Male donor-to-male recipient transplants had lower graft failure, particularly better than female to male (5%-13% lower risk). HLA mismatch was important in all donor types. Obesity of both the recipient (8%-18% higher risk) and donor (5%-11% higher risk) was associated with higher graft loss, as were donor-recipient weight ratios of <75%, compared with transplants where both parties were of similar weight (9%-12% higher risk). These models are used to create a calculator of estimated graft survival for living donors.

Conclusions: This calculator provides useful information to donors, candidates, and physicians of estimated outcomes and potentially in allowing candidates to choose among several living donors. It may also help inform candidates with compatible donors on the advisability of joining a KPD program.

Keywords: Attention; Female; HLA Antigens; Living Donors; Organ Procurement; Proportional Hazards Models; Registries; Survival Rate; Transplant Recipients; Unrelated Donors; age; body size; donor exchange; end-stage renal disease; gender; graft survival; kidney donation; kidney transplantation; obesity; renal failure; risk factors; transplant outcomes; transplantation.

Figure 1.

Trends in the unadjusted probability of graft failure at 5 years for deceased donor, living unrelated donor, and living related transplant recipients, 1998–2008. Graft failure probabilities shown for years in which five years of followup is available.

Figure 2.

Adjusted risk of graft failure hazard ratio comparisons for donor and recipient age group among living donor kidney transplant recipients, 1998–2012. Adjusted for calendar year as well as recipient race and ethnicity, ESRD cause, panel reactive antibody at transplant, previous transplant, years of ESRD, hepatitis C serology, and insurance. In addition, all models were adjusted for the following donor-recipient combinations: sex, obesity status (obese if body mass index ≥30), weight ratio, height ratio, and HLA mismatch.

Figure 3.

Adjusted probability (and 95% confidence interval) of graft failure at 5 and 10 years by donor-recipient sex for recipients of living unrelated, living related, and deceased donor transplants, 1998–2012. Adjusted for calendar year as well as recipient race and ethnicity, ESRD cause, panel reactive antibody at transplant, previous transplant, years of ESRD, hepatitis C serology, and insurance. In addition, all models were adjusted for the following donor-recipient combinations: age, obesity status (obese if body mass index ≥30), weight ratio, height ratio, and HLA mismatch. Each probability pertains to the average donor and recipient characteristic for each model. F, female; M, male.

Figure 4.

Donor-recipient sex distribution for living not biologically related, living biologically related, deceased, and kidney paired donation groups, 1998–2012.