In kidney transplant recipients with BK polyomavirus infection, early BK nephropathy, microvascular inflammation, and serum creatinine are risk factors for graft loss

Abstract

Background: Little information is available on the risk factors for graft loss in kidney transplant recipients with BK polyomavirus (BKPyV) nephropathy (BKVN) in the presence or absence of antibody-mediated rejection (AMR).

Methods: We examined the risk factors for graft loss in consecutive kidney allograft recipients with biopsy-confirmed BKVN, with or without concomitant AMR.

Results: A total of 1904 kidney transplants were performed at our institution during 2005-2011. Of these, 330 (17.33%) were diagnosed with BKPyV viremia, and 69 were diagnosed with BKVN (3.6%). Eleven patients had a concomitant diagnosis of AMR. Patients with AMR were characterized by significantly higher peak panel-reactive antibody, retransplant rates, and desensitization preconditioning at the time of transplantation, as well as microvascular inflammation (MVI = glomerulitis + peritubular capillaritis), C4d score, and donor-specific antibody at the time of diagnosis (P ≤ 0.01). Treatment with plasma exchange, intravenous immunoglobulin, and cidofovir was more prevalent in this group (P ≤ 0.02). Univariate analyses assessing the risk factors for graft loss in all patients with BKVN, identified an independent association of African-American race, deceased-donor transplantation, serum creatinine (Scr), MVI, and early disease (BKVN within 6 months of transplant) with poor outcomes. Multivariate analyses retained only 3 variables: Scr >2 mg/dL (hazard ratio [HR] = 4.3, 95% confidence interval [CI] 1.9-9.7, P = 0.0004), early BKVN (HR = 2.7, 95% CI 1.3-5.3, P = 0.004), and MVI (HR = 1.8, 95% CI 1.2-2.8, P = 0.008).

Conclusions: These observations suggest that, in patients with BK infection, early BKVN, Scr >2, and MVI are predictors of poor outcomes. Further studies are needed to determine effective treatment strategies for BKVN, with or without AMR.

Keywords: BK nephropathy; BK virus; kidney transplantation; risk factors.