Purpose: This study aims to evaluate the clinicopathological factors affecting worse kidney allograft outcomes in pathological chronic active antibody-mediated rejection (pCAABMR) diagnosed by Banff 2013 criteria.

Methods: A total of 422 biopsies from 344 kidney transplant recipients were performed in our institute between January 2016 and April 2018. Among them, 33 biopsies (7.8%) from 29 recipients were diagnosed as pCAABMR. We retrospectively investigated pathological and clinical features of pCAABMR recipients and their graft outcomes.

Results: The presence of DSA was evaluated in 21 recipients, and DSA was detected in 15 recipients (71%). Among 29 recipients, we could follow allograft survivals in 26 recipients. Microvascular inflammation (MVI) scores (g+ptc, and C4d) were not significant predictors for graft survival. In contrast, cg, cv, ct, ci, and proteinuria were significant predictors by Log-rank analyses (p = 0.013, 0.005, 0.017, 0.017, and 0.009, respectively). When each variable was adjusted for eGFR at the time of biopsies, only proteinuria and cv score were significant predictors (hazard ratio [95% confidence interval], p-value: 8.60 [1.37 – 5.91], p = 0.028; 10.67 [1.34 – 217.92], p = 0.025; respectively).

Conclusion: In recipients with pCAAMR in Banff 2013, chronic tissue injury scores, not MVI scores, may be related to kidney function at the biopsy. Proteinuria and cv status may be important for the prediction of graft survival.