Recent studies document that MVI increases DCGF. However, the relationship between components of MVI (Banff scores g, cg, ptc) and macrovascular inflammation (v) have not been rigorously examined in a large patient cohort. We sought to define the relationship between g, cg, ptc, and v and their impact on DCGF.

Methods: Patients were enrolled in DeKAF, a multicenter study of late renal allograft outcome. A prospective cohort (PC) included 606 patients enrolled at transplant who subsequently underwent KTxBx for increase in serum creatinine (Scr) or new onset proteinuria; the cross-sectional cohort (CSC) included 489 patients with stable graft function up to Jan 2006 who subsequently underwent KTxBx for increased Scr or proteinuria; patients with biopsies showing BK virus or recurrent glomerulonephritis were excluded. KTxBx were read by a central pathologist in blinded fashion according to expanded Banff criteria. Patients with biopsies showing BK virus or recurrent disease were excluded from analysis.

Results: DCGF for the first 20 months following KTxBx was identical in both cohorts. MVI scores (g, cg, ptc) >0 were more frequent in the CSC than the PC. Only 5% of biopsies (58/1095) had v scores >0, but they were more frequent in PC. MVI scores (g, cg, and ptc) were all highly correlated with each other; v scores were weakly correlated with MVI. By univariate Cox analysis, g>0, ptc>0, and cg>0 all increased hazard for DCGF, but in none of these was there further increase in hazard with scores > 1, nor was the hazard increased when more than one of ptc, g, or cg was >0. In the presence of MVI (ptc>0 or g>0), graft survival was similar whether cg=0 or cg>0 (Figure).

Conclusions: Any MVI >0 led to a similar increase in hazard of DCGF. With MVI present, cg >0 had no further impact on DCGF. Our findings underscore the importance of any MVI on graft survival. MVI should be diagnosed with any ptc, g, or cg >0. The results also call into question the distinction between acute and chronic MVI based on cg >0.

CITATION INFORMATION: Grande J., Hunsicker L., LeDuc R., Matas A., The DeKAF Consortium Components of Microvascular Inflammation (MVI) in Kidney Transplant Biopsies (KTxBX) Impacting Late Death Censored Graft Failure (DCGF) Am J Transplant. 2017;17 (suppl 3).

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