Validation of the Maryland Aggregate Pathology Index (MAPI), a pre‐implantation scoring system that predicts graft outcome

Abstract

Predicting graft outcome after renal transplantation based on donor histological features has remained elusive and is subject to institutional variability. We have shown in a retrospective study that the Maryland Aggregate Pathology Index score reliably predicts graft outcome. We sought to validate the scoring system in our center and a second transplant center. We analyzed 140 deceased donor kidneys pre-implantation biopsies from center 1 and 65 from center 2. The patients had a mean follow-up of 695 ± 424 and 656 ± 305 d respectively. Although MAPI scores were similar, there were significant differences in donor and recipient parameters between both centers. Despite this, MAPI was predictive of graft outcome for both centers by Cox univariate, multivariate and time dependent ROC analysis. For center 1 and 2, three yr graft survival within each MAPI group was statistically equivalent. The three-yr graft survival at center 1 for low, intermediate, and high MAPI groups were 84.3%, 56.5%, and 50.0%, respectively, p ≤ 0.0001, and at center 2 were 83.3%, 33.3%, and 33.3%, p = 0.006. MAPI, which is based on a pre-implantation biopsy, demonstrated similar predictive and outcome results from both centers. As expanded criteria donors (ECD) criteria have redefined marginal kidneys, MAPI has the potential to further define ECD kidneys, increase utilization, and ultimately improve outcomes.

Variation in use of procurement biopsies and its implications for discard of deceased donor kidneys recovered for transplantation

“…donor morphology for 500 allografts and developed an index of chronic injury 21. The Maryland Aggregate Pathology Index (MAPI) was published in 2014 using contemporary analysis of wedge biopsies 22. The Maryland Aggregate Pathology Index (MAPI) was published in 2014 using contemporary analysis of wedge biopsies 22.…”

Correlation of acute tubular injury in reperfusion biopsy with renal transplant outcomes

“…Our study adds to this body of literature by demonstrating that ATI did not correlate with death censored graft and overall patient survival. Several studies have correlated CI with decreased graft survival . Other studies that found no association were able to show a correlation with a composite clinico‐pathologic score .…”

“…ATI in literature has been inconsistently associated with DGF, AR, and lower creatinine at various time points posttransplantation. 7,[22][23][24][25][26]28 10,17,46 Other studies that found no association 18,47 were able to show a correlation with a composite clinico-pathologic score. 18…”

What's the score? A comparison of deceased donor kidney scoring systems and correlation with graft outcome

“…Using this point system, a receiver operating curve analysis was used to generate cutoffs that best stratified post‐transplant graft survival. Based on this analysis, a low (≤7), medium, and high‐risk score was developed that maximized sensitivity and specificity . Furthermore, a multivariate Cox analysis with MAPI and donor clinical features revealed that the MAPI score was the only variable significantly associated with graft loss.…”

“…The relative risk of graft loss increased by 21% for every point increase in the overall score. The discriminatory ability of the MAPI score was validated by independent pathologists, and by two independent transplant centers, supporting the use of MAPI as a scoring system with excellent generalizability …”