*Purpose: Organ selectivity for transplantation can be quite challenging, especially for marginal kidneys. We examined the prognostic utility of the Maryland Aggregate Pathology Index (MAPI) and Remuzzi scoring systems in extended criteria donor kidneys (ECD) and compared them to standard criteria grafts (SCD), to evaluate their predictive value in determining graft dysfunction.

*Methods: A retrospective study was completed on ECD (n=77) and SCD (n=28) kidney recipients from 2014 to 2017. Post-reperfusion biopsies were retrospectively scored using both MAPI and Remuzzi criteria. MAPI and Remuzzi scores were stratified into low and high pathology index groups. A low pathology index was defined as a MAPI score of 0-7 and Remuzzi score of 0-3; whereas an intermediate/high pathology index was defined as a MAPI score of 8-15 and Remuzzi score ≥4. Statistical analysis was used to determine the predictive accuracy of biopsy scoring on a variety of factors including donor demographics, cold ischemic time (CIT), delayed graft function (DGF), slow graft function (SGF), graft failure, and recipient survival.

*Results: Recipient demographics and were similar between the two groups. Of the 77 ECD recipients, 66 (86%) were categorized as low pathology index and 11 (14%) as intermediate/high pathology index. Regardless of CIT, both MAPI and Remuzzi indices were equivalent in their predictive abilities of determining DGF and SGF, regardless of pathological sub-stratification. ECD recipients with a MAPI/Remuzzi low pathology indices experienced DGF rates of 36.3% and 37.3%, respectively, compared to 21.4% in the SCD group (p<0.05). ECD recipients with intermediate/high pathology indices experienced DGF rates of 45.5% and 40.3%, respectively. In the ECD group, there were only 4% graft failures and 5% patient deaths recorded over the study period, compared to 0% in the SCD group.

*Conclusions: This is the first study evaluating the utility of the MAPI index in ECD kidneys. Our data suggests that MAPI/Remuzzi scores can be used interchangeably in predicting graft dysfunction and graft loss in ECD kidneys. As expected, DGF and SGF rates are higher in patients receiving the ECD grafts compared to those with SCD grafts. Regardless of low or intermediate/high index on the MAPI/Remuzzi scale, ECD kidneys performed similarly and produced acceptable patient outcomes. In the face of a diminishing organ supply, ECD grafts should be considered for transplantation, especially in selectively screened patients. Further investigation is warranted to elucidate these associations.

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