LAUSR

Introduction: Remuzzi score is one of the most commonly used scoring systems for donor kidney quality assessment, originally based on the wedge biopsy that requires at least 25 glomeruli. When the pathological evaluation is performed using the needle biopsy, at least 7 glomeruli are required, but there is no well-recognized minimal value for glomerular number required. In addition, whether the Remuzzi scoring system is suitable for donors of all ages remains controversial. This study investigated the effects of the glomerular number and the donor age on the performance of the Remuzzi score to predict the renal allograft function. Methods: Totally 144 renal transplant with donor pre-transplant needle biopsy were included. Paraffin-embedded sections were retrospectively re-assessed. The number of glomeruli all exceeded 7. The cases were divided into two groups according to the median of glomerular number: 8-11 and ≥12 glomeruli. They were also categorized into donor age <40year and ≥40-year groups. The association between the Remuzzi scores and the incidence of DGF, 1-year eGFR, and graft survival rate were investigated. Remuzzi score is graded as mild (0-3), moderate (4-6), or severe (7-12). Results and Discussion: Compared with Grade mild (N = 119), Grade moderate+severe (Grade M-S) (N = 25) had higher risk of DGF (32.0% vs 10.9%, P = 0.007), lower 1-year eGFR (42.9 ± 23.3 vs 61.6 ± 27.9 mL / min / 1.73m, P = 0.002) and reduced 1-year graft survival (86.1% vs 98.2%, P = 0.008). The median glomerular numbers in the two glomerular number subgroups were 10 (9-11) and 15 (13-19) respectively (P <0.001). There was no significant difference in donor age, recipient age, total Remuzzi score, and sub-item scores between the two subgroups. Only in the subgroup with ≥12 glomeruli was the Remuzzi score correlated with the incidence of DGF, 1-year eGFR and 1-year graft survival (Table 1). Eighty-six cases with ≥12 glomeruli were selected for further analysis. The proportion of Grade M-S was only 7.8% (4/51) in cases with donor age <40 years. The 1-year eGFR of Grade M-S was lower than that of Grade mild (57.5 ± 20.2 vs 73.1 ± 31.5 mL/min / 1.73m, P=0.289), but still acceptable. The insignificance was likely due to the small number of cases with Grade M-S and donor age < 40 years. In cases with donor age ≥40 years, the proportion of Grade M-S accounted for 37.1% (13/35) and the 1-year eGFR of Grade M-S was lower than that of Grade mild (31.5 ± 22.1 vs 50.6 ± 23.7 mL/ min / 1.73m, P=0.055) (Table 2). When the Remuzzi grade was mild, a significant decrease of 1-year eGFR was identified in the recipients with donor age ≥40 years compared with those with donor age <40 years (50.6 ± 23.7 vs 73.1 ± 31.5 mL/min / 1.73m, P = 0.003); When the Remuzzi grade was moderate+severe, the 1-year eGFR of the recipients with donor age <40 years tended to be better than those with donor age ≥40 years (57.5 ± 20.2 vs 31.5 ± 22.1 mL/min / 1.73m, P = 0.109). There may exist an interactive effect between donor age and Remuzzi grade. Due to the international controversy whether the prognosis of single kidney transplant using the donor kidney with Remuzzi score of 4 points is worse than or similar to that of 0-3 points, we compared the 1-year eGFR among the Remuzzi score of 4 points, 0-3 points, and ≥5 points. The difference between the three groups was statistically significant (P = 0.003). Four points was worse than 0-3 points (41.2 ± 26.4 vs 65.9 ± 30.9 mL / min / 1.73m, P = 0.012), but numerically better than ≥5 points (41.2 ± 26.4 vs 31.2 ± 19.1 mL / min / 1.73m, P = 0.512). Conclusions: The histological assessment of needle biopsies using the Remuzzi scoring system requires a minimum of 12 glomeruli. When assessing donor quality using the Remuzzi scoring system, the donor age should also be considered. For donors younger than 40 years old, a pre-transplant biopsy for chronic lesions evaluation may not be cost-effective. The allograft function after kidney transplantation using donors with Remuzzi score of 4 was worse than 0-3.