Impact of donor kidney weight to recipient body weight ratio on long-term graft outcomes in live donor kidney transplantation

Abstract

Background: Kidney weight has been suggested as a surrogate marker for nephron numbers and renal function. Small donor kid ney sizes relative to recipient body size is an important contributor to short-term graft renal function, but the impact of size mis matching on long-term graft outcomes remains unknown. This study is aimed to evaluate the impact of the donor kidney weight to recipient body weight ratio (KW/BW) on long-term graft survival in live donor kidney transplantation. Methods: We performed a longitudinal cohort study in 1,397 patients who underwent live donor kidney transplantation between 2000 and 2016 at Severance Hospital. Following cold perfusion and back table surgery, the kidney was weighted on the same electronic weighting scale by the surgeon. Patients were grouped into four groups according to KW/BW quartiles. Results: During a median follow-up period of 127 months, 245 graft losses occurred (172 graft failures and 73 patient deaths). The 10-year death-censored graft survival rates were 86.9% in the lowest quartile, 90.4% in the second quartile, 90.5% in the third quartile, and 92.4% in the highest quartile (P=0.002). Multivariable analysis revealed that the lowest KW/BW (hazard ratio [HR], 2.16; 95% confidence interval [CI], 1.33-3.48; P=0.002) and second lowest KW/BW (HR, 1.69; 95% CI, 1.06-2.70; P=0.029) groups were significantly associated with death-censored graft failure compared with the highest KW/BW group. Patients with lower KW/BW exhibited consistently lower estimated glomerular filtration rates than those with higher KW/BW. Conclusions: Low KW/BW ratio is significantly associated with long-term graft outcome in live donor kidney transplantation.