[Analysis on BK virus associated nephropathy related risk factors in renal transplant recipients]

To analyze the risk factors affecting BK virus associated nephropathy (BKVAN) after kidney transplantation.

Three screening methods for BKVAN including quantitative PCR assay for BK virus (BKV) DNA load in urine and plasma and quantitative assay of urine cytology concurrently with renal transplant biopsies for the evaluation of 615 patients from January 2006 to December 2014 were used. The renal allograft biopsy specimens were analyzed by routine histologic examination, immunohistochemistry and classified into three categories of BKVAN. Potential variables were analyzed by Logistic regression model multivariate analysis to assess and rank BKVAN related risk factors.

The positive rate of urine decoy cell , BKV viruria and viremia in 615 renal recipients were 13.7% (84/615), 29.3% (180/615), and 8.8% (54/615), respectively. BKVAN were diagnosed in 49 recipients. The incidence and the median level of the number of the decoy cell, BK viral load in urine and plasma were higher in the BKVAN group than those in non-BKVAN group (all P<0.05). Tacrolimus (Tac) combined with mycophenolic acid (MPA) protocol (OR=12.4, P=0.001) and severe pneumonia post-transplant (OR=3.7, P=0.001) were the independent risk factors impacting on BKVAN in renal recipients.

The renal recipients with high level of BKV replication, whose immunosuppressant protocol include Tac and MPA, should be suspected the diagnosis of BKVAN.