Aim: To determine the utility of screening for BK viruria (BKVR) to predict the development of BK viraemia within the first year of renal transplantation.

Background: BK virus infection affects 15% of renal transplants within the first year post transplantation. Preventative strategies involve screening for the development of BK viraemia using serum PCR and immunosuppression reduction following detection. Other screening tools, such as viruria measurements, are not routinely used due to their poor correlation with BK nephropathy. In all but rare cases, BK viraemia is preceded by BKVR. However, there is scarce literature regarding the predictive value of BKVR for the development of BK viraemia.

Method: A retrospective analysis of a single centre cohort of patients transplanted from January 2013 to October 2015 with a minimum of 12 months follow-up. Data collected included demographics, transplant characteristics and results of routine screening for BK viruria and viraemia, with particular focus upon the first 3 months post transplantation.

Results: 182 patients underwent screening for BKVR and viraemia over this timeframe. 62 patients (34%) had viruria, 40 patients (22%) viraemia and 30 patients (16%) had histological evidence of BK nephropathy (SV40 positive) or rejection during or after the period of viraemia. Of those with BKVR, 40 patients (61%) developed viraemia within the first twelve months post transplantation (p<0.05). Of these 40 patients, 37 were positive for BKVR at 3 months (92.5%). All patients negative for BKVR at 3 months did not develop viraemia. Median time between the development of BKVR and viraemia was 24.5 days (9-34). BKVR had a greater sensitivity and specificity for the prediction of BK viraemia at 2 months (sensitivity 77%, specificity 95%, PPV 82% and NPV 93%) compared with one month (sensitivity 40%; specificity 90%; PPV 82%; NPV 86%).

Conclusion: BK viruria preceded the development of BK viraemia by a median of 24.5 days and was predictive of the subsequent development of viraemia. Screening for an optimum cut off of BK viruria within the first three months post renal transplantation could identify those at high risk for the development of viraemia.

CITATION INFORMATION: Lioufas N, Masterson R, Hughes P. BK Viruria Levels within 3 Months Post Renal Transplantation Can Predict the Development of BK Viraemia. Am J Transplant. 2017;17 (suppl 3).

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