Using implantation biopsies as a surrogate to evaluate selection criteria for living kidney donors

BACKGROUND: The acceptance criteria used for living kidney donors are largely theoretical, as they are not clearly linked to outcomes. The goal of this study was to use implantation biopsies as a surrogate outcome marker to evaluate our living kidney donor selection criteria. METHODS: One thousand six hundred sequential living kidney donor biopsies were performed between 2001 and 2011. Implantation biopsies were assessed by dedicated renal pathologists according to the Banff criteria. Biopsies with any chronic score of 2 or higher were deemed to have moderate to severe changes (MSC). RESULTS: MSC was present in 4% (n=65) of implantation biopsies and occurred across a wide range of age and other demographics. By multivariate analysis, donor age (odds ratio [95% confidence interval], 1.060 [1.035-1.086]; P<0.0001) and donor systolic blood pressure (SBP) (odds ratio [95% confidence interval], 1.022 [1.006-1.037]; P=0.0060) were associated with MSC. Donor gender, body mass index, diastolic blood pressure, glomerular filtration rate, and urinary microalbuminuria were not. MSC was further increased in donors older than 60 years with SBP>140 (30% [7 of 23]) and donors older than 60 years with SBP>140 and glomerular filtration rate above the 25th percentile (42.8% [3 of 7]). In donors younger than 60 years, combining factors did not show an increased prevalence of MSC. At follow-up, renal function was similar in donors with and without MSC. CONCLUSIONS: MSC occurred sporadically in donors with varied characteristics. Although we did not detect patterns to support specific changes in our acceptance criteria, certain subgroups of donors might benefit from close follow-up.