Is the Living Donor Kidney Profile Index Valuable in Japanese Patients?

The Living Kidney Donor Profile Index (LKDPI) was recently proposed in the United States to evaluate living donor quality. Japan has a largely different renal transplant circumstance, such as a high ABO incompatibility rate. The aim of this study was to validate the LKDPI among the Japanese population and adjust the score.

We performed a retrospective analysis of 133 living donors in renal transplant in our institution. We analyzed the clinical characteristics and outcomes, and created a modified LKDPI score considering the favorable ABO incompatible kidney transplant outcomes in Japan.

Median (interquartile range [IQR]) donor age was 59 (51 to 65) and median (IQR) body mass index was 22.9 kg/m² (20.9 to 25.2). ABO incompatibility rate was 28.5%. Median (IQR) donor estimated glomerular filtration rate (eGFR) (Chronic Kidney Disease Epidemiology Collaboration equation) was 108.7 mL/min/1.73 m² (99.9 to 115.5). The 1-year graft survival rate was 98.5%, and the 3-year graft survival rate was 97%. The incidence of antibody mediated rejection was 5.2%. The median (IQR) LKDPI score was 30.2 (11.8 to 46.8). This was significantly higher than the previously reported score in the United States, which was 12.8 (-0.8 to 27.2). The modified LKDPI (mLKDPI) score was 23.2 (4.1 to 35.1). LKDPI and mLKDPI did not show a diagnostic value in graft survival; however, LKDPI and mLKDPI showed significant diagnostic value in eGFR at 1 year (area under the curve [AUC]=0.627, P = .017; and AUC=0.673, P = .01).

Our outcomes had better survival even though with higher ABO incompatibility rate. According to original LKDPI, our donor pool is higher than the general US population. In this study, lower LKDPI tended to be associated with good allograft function, and mLKDPI has better diagnostic value than LKDPI. To compare internationally, an adjusted model for Japan might be necessary based on the outcomes of a large population.