A direct association of polyomavirus BK viruria with deterioration of renal allograft function in renal transplant patients

Background: Polyomavirus BK virus (BKV) causes a BKV-associated nephropathy (BKVAN), frequently causing allograft dysfunction in renal transplant recipients. As BK viruria is a surrogate marker for early detection of BKVAN, the aim of this study was to clarify an association between BK viruria and allograft dysfunction in renal transplant recipients. Methods: One hundred and six renal transplant recipients with average 5.9-yr transplant duration received screening for quantification of BK viruria detected by real time polymerase chain reaction and were followed up for 12 months. Results: Twenty-six patients (25%) had detectable BK viruria. In comparison of the patients without BK viruria, more patients in the BK viruria group were treated with steroids and had a past history of acute rejection. There was no difference in sex, age, transplant duration, allograft type and previous cytomegalovirus infection. During follow-up, the patients with BK viruria had higher serum creatinine levels at the sixth, ninth and 12th month. Multiple logistic regression analysis revealed that BK viruria was the only risk factor for more than 25% or 50% rise of serum creatinine level above baseline at the end of one yr follow-up. Conclusions: BK viruria alone is associated with allograft dysfunction and early intervention is indicated.