Study 3: early steroid cessation-avoidance regimens are associated with a lower incidence of polyomavirus nephropathy compared with steroid-based immunosuppression in kidney transplant recipients

Late-Onset BK Viruria in Renal Transplant Recipients

BACKGROUND

Most cases of BK virus (BKV) infections emerge within the 1st years of kidney transplantation. We aimed to determine the prevalence of late-onset BKV infection and whether there are any differences between risk factors in early and late BKV infections.

METHODS

In this single-center retrospective study, we reviewed 300 kidney transplant recipients that were under regular follow-up and selected recipients with BKV infection and recorded associated risk factors, connection with immunosuppression, and responses to modification of treatment.

RESULTS

BKV was detected within the 1st 5 years after transplantation in 20 patients (6.6%, group 1) and after 5 years in 15 patients (5.0%, group 2). There were no significant differences between the 2 groups regarding age, sex, sex mismatches, donor type, BKV elimination time, serum creatinine, and estimated glomerular filtration rate at the times of BKV detection and last follow-up visit. In group 1, 2 recipients had biopsy-proven BKV-associated nephropathy (BKVAN), 3 recipients had BK viruria and viremia without BKVAN (biopsy proven), and 15 recipients (75%) had only BK viruria. In group 2, all of the patients had only BK viruria. In this group, on detection of BK viruria and immediate modification of immunosuppressive regimens prevented BK viremia.

CONCLUSIONS

Routine screening of renal transplant recipients for BKV was indicated not only during the 1st 5 years, but also for the full follow-up period after transplantation.

The decade of polyomavirus BK-associated nephropathy: state of affairs. Transplantation. 2009;87:621-630. [PMID: 19295303 DOI: 10.1097/tp.0b013e318197c17d]

In the last 10 years, better immunosuppression drugs have decreased the rates of acute rejection in kidney transplantation but have also led to the emergence of polyomavirus-associated nephropathy (PVAN). This occurs in 1% to 10% of patients with kidney transplantion and is caused by BK virus in more than 95% of cases. Less than 5% of cases are attributed to the JC virus. Initially, lack of recognition or late diagnosis of PVAN resulted in rapid loss of graft function in more than 50% of patients. In recent years, it has become clear that early diagnosis and timely reduction in immunosuppression is the only proven measure, which significantly affects the outcome of PVAN. Diverse interventions have been explored including the adjunctive use of cidofovir, leflunomide, fluoroquinolones, and intravenous immunoglobulins. Allograft histology is needed to definitively establish the diagnosis of PVAN, but is of limited sensitivity in the early stage of disease. Well-established techniques and protocols for systematic screening by urine cytology and quantitative molecular-genetic techniques allow now for timely intervention before irreversible parenchymal changes occur. Moreover, preemptive reduction in immunosuppression is most effective in presumptive PVAN as defined by surrogate markers (i.e., high BK virus viremia). In this setting, preservation of graft function can be considered the rule. Nevertheless, the recovery of BK virus-specific T-cell immunity may require prolonged periods during which cytopathic damage may continue to accumulate. Despite remarkable progress in the field, important challenges remain, such as the rare patient with PVAN refractory to any intervention and the newly recognized association of PVAN with urogenital tumors.

The prevalence of BK polyomavirus infection in outpatient kidney transplant recipients followed in a single center

BACKGROUND

BK polyomavirus (BKV) infection has emerged as an important cause of renal allograft loss. There is no proven therapy, and much basic clinical information is still lacking.

METHODS

We serially enrolled 95 outpatient renal transplant recipients (43% of whom were African American) in a single center cross-sectional screening study to determine the prevalence of BKV infection by whole blood polymerase chain reaction, and the prevalence of decoy cells by urinalysis and cytology. We also investigated the demographic and clinical factors associated with BKV infection, and the performance of urinalysis for decoy cells as a screening test for BKV infection.

RESULTS

The point prevalence of active BKV viremia was 7.4%. When subjects without active viremia but with a history of viremia and/or nephropathy were included, the overall prevalence was 15.8%. Urinary decoy cells were common, present in 50% of subjects at study entry. Urinalysis for decoy cells as a screen for BKV viremia had a sensitivity of 86%, specificity of 52%, positive predictive value of 13% and negative predictive value of 98%.

CONCLUSIONS

Decoy cells on urinalysis were the only factor independently associated with an increased risk of BKV infection on multivariate analysis. Although associated with BKV infection on univariate analysis, thymoglobulin, mycophenolate mofetil, and tacrolimus use were not independently associated with BKV infection on multivariate analysis, neither were history of acute rejection, gender, race, nor cause of end-stage renal disease.