Does Allograft Size Really Matter in the Long-Term Outcome of Living Donor Kidney Transplantation?

•Volume/Weight (Vol/Wt) ratio had a close association with short-term allograft function.•Association between Vol/Wt ratio and graft function was not sustainable for the long term.•The underlying mechanism may be the change in recipients’ physiological demands.

BackgroundIncreased allograft mass in living donor kidney transplantation has been recognized as a predictor factor of better short-term allograft function. We evaluated whether donor kidney volume adjusted for recipient body weight is associated with long-term allograft function in living donor kidney transplantation.MethodsWe analyzed 67 living donors and their recipients who underwent transplantation between 2003 and 2007. Estimated glomerular filtration rate (eGFR) and serum creatinine levels at 1, 2, 3, 4, and 5 years post-transplantation were recorded for all recipients. Transplanted kidney volumes were measured using 3-D helical computed tomography scanning. A transplant kidney volume-recipient body weight (Vol/Wt) ratio was calculated for each donor-recipient pair. The subjects were divided into tertiles according to Vol/Wt ratios: low (<2.16), medium (2.16–2.88), and high (>2.88).ResultsVol/Wt ratio significantly correlated with recipient eGFR and serum creatinine levels at 1, 2, 3, and 4 years post-transplantation (r = .48, P < .0001; r = .46, P < .0001; r = .47, P < .0001; r = .26, P = .037, respectively, for eGFR; r = −.53, P < .0001; r = −.50, P < .0001; r = −.44, P < .0001; r = −.37, P = .003, respectively, for serum creatinine) but not at 5 years (r = .12, P = .406 for eGFR; r = −.21, P = .110 for serum creatinine). Whereas recipient eGFR increased significantly in a graded fashion among low to high Vol/Wt ratio groups during 1 to 3 years post-transplantation, there was no difference in eGFR values between Vol/Wt ratio groups at 4 and 5 years (P = .21 and .71, respectively).ConclusionVol/Wt ratio is not associated with long-term allograft function in living donor kidney transplantation.