Biopsy-proven BK virus nephropathy in kidney transplant patients: risk factors, prevalence and treatment approach

Purpose: BK virus nephropathy (BKVN) is a latent infection and it is closely associated with immunsuppressive therapy. We aimed in this study to evaluate biopsy-proven BKVN and investigate frequency, risk factors and treatment management. 
Materials and Methods: In this study, 422 kidney transplant recipients were analysed retrospectively between April 2014 and April 2020 for biopsy-proven BK virus nephropathy. Group I included 16 kidney transplant patients with biopsy-proven BK nephropathy and group II included 36 kidney transplant patients with negative BK virus nephropathy. We aimed demographic, clinical features of kidney transplant recipients with BKVN (group I, n: 16 ) and non-BKVN (group II, n:36) were compared and the factors affecting of BKVN. 
Results: The mean age of grup I and group II were were 41±14.8 years and 39±15.2 respectively. The patients mean follow-up period of 43±11.2 months. Serum creatinine and proteinuria degree were significantly higher in the group with BKVN. In order to reduce the dose of immunosuppression in patients with BKVN, tacrolimus treatment was discontinued in 8 patients, and they were switched to everolimus + MMF + prednisone treatment, leflunamide + MMF + prednisone treatment in 4 patients, and sirolimus + MMF + prednisone treatment in 4 patients. The mean serum creatinine level of the patients who were followed up were observed as 1.78±0.98 mg/dl in group I. 
Conclusion: In our center, the prevalance of BKVN was found 3.92% during the study period. Reduction of dose immunosuppressive therapy is the most effective treatment. It is thought that there was no differences between Leflunamide and other approaches for treatment. Early diagnosis and screening (frequently intervals) seems to be most effective way for BKVN.