Outcomes of Screening for BK Viraemia and BK Nephropathy in Renal Transplant Recipients

Abstract

Background and Aims BK virus is an important cause of renal allograft loss in the renal transplant population. There is limited data regarding intermediate to long-term outcomes in patients with BK viraemia. Effects of routine screening are not well established, with prevalence in prospectively screened cohorts ranging from 11 to 43%. Our aim was to describe the burden of BK viraemia (BKV) and BK nephropathy (BKN) in a large single transplant centre. Methods We conducted a retrospective cohort study of 526 patients transplanted between 2008 and 2015, when routine screening (at 3 and 12 months post transplantation) was established. Results 71 patients (13%) developed BKV and 20 (4%) developed BKN during the study period. The median follow-up was 50.9 months (IQR 28.4-82.2) with a minimum follow-up of 12 months. More than 95% of patients were screened for BK at 3 months. All but two patients with BKN had intermediate or high levels of BKV>1000copies/ml. The majority of patients had basiliximab induction (73%) and maintenance tacrolimus, mycophenolate and prednisolone (94%). Race was strongly associated with BKV (p<0.001), with Asian/Indian and Aboriginal/Pacific Islander groups both having an increased risk compared to Caucasian (OR Asian/Indian compared to Caucasian 2.49; 95%CI 1.20-5.16). There was a trend toward higher rates of BKV with increasing HLA mismatch (p=0.065). Acute rejection and thymoglobulin use were not associated with BKV (OR 1.16, p=0.751; OR 0.71, p=0.349 respectively). Conclusions BKV was detected in 13% of our cohort and Asian and Indian race was associated with a significantly increased risk. Routine screening for BKV is effective and enables optimal management of immunosuppression to minimise progression.