Quantifying Donor Effects on Transplant Outcomes Using Kidney Pairs from Deceased Donors

Abstract

Background and objectives: In kidney transplantation, the relative contribution of donor versus other factors on clinical outcomes is unknown. We sought to quantify overall donor effects on transplant outcomes for kidney donations from deceased donors.

Design, setting, participants, & measurements: For paired donations from deceased donors resulting in transplants to different recipients, the magnitude of donor effects can be quantified by examining the excess of concordant outcomes within kidney pairs beyond chance concordance. Using data from the Organ Procurement and Transplantation Network between the years 2013 and 2017, we examined concordance measures for delayed graft function, death-censored 1-year graft failure, and death-censored 3-year graft failure. The concordance measures were excess relative risk, excess absolute risk, and the fixation index (where zero is no concordance and one is perfect concordance). We further examined concordance in strata of kidneys with similar values of the Kidney Donor Profile Index, a common metric of organ quality.

Results: If the transplant of the kidney mate resulted in delayed graft function, risk for delayed graft function was 19% higher (95% confidence interval [95% CI], 18% to 20%), or 1.76-fold higher (95% CI, 1.73- to 1.80-fold), than baseline. If a kidney graft failed within 1 year, then the kidney mate's risk of failure was 6% higher (95% CI, 4% to 9%), or 2.85-fold higher (95% CI, 2.25- to 3.48-fold), than baseline. For 3-year graft failure, the excess absolute risk was 7% (95% CI, 4% to 10%) but excess relative risk was smaller, 1.91-fold (95% CI, 1.56- to 2.28-fold). Fixation indices were 0.25 for delayed graft function (95% CI, 0.24 to 0.27), 0.07 for 1-year graft failure (95% CI, 0.04 to 0.09), and 0.07 for 3-year graft failure (95% CI, 0.04 to 0.10). Results were similar in strata of kidneys with a similar Kidney Donor Profile Index.

Conclusions: Overall results indicated that the donor constitution has small or moderate effect on post-transplant clinical outcomes.

Keywords: cadaver organ transplantation; confidence intervals; death; delayed graft function; kidney; kidney transplantation; risk; survival; tissue donors; transplant outcomes; transplantation; transplants.

Graphical abstract

Figure 1.

The analytic dataset for each outcome was determined by the time frame of each outcome, with minimal exclusions for recipient death or missing KDPI. KDPI, Kidney Donor Profile Index.

Figure 2.

Donor effects are moderate for DGF and more modest for graft failure outcomes. Relatively large excess relative risks for 1-year graft failure is against a background of low incidence. For all three outcomes, donor effects in strata of kidneys with similar KDPI are similar to overall results. Concordance metrics for delayed graft function, 1-year death-censored graft failure, and 3-year death-censored graft failure among pairs of donor kidneys overall and in strata of similar KDPI. Three metrics are shown: the fixation index f, excess relative risk, and excess absolute risk.