A prospective study of BK-virus-associated haemorrhagic cystitis in paediatric patients undergoing allogeneic haematopoietic stem cell transplantation.

We investigated the incidence, risk factors and outcome of haemorrhagic cystitis (HC) in paediatric patients undergoing HSCT and the predictive value of BK viruria and viraemia for developing HC. Over a period of 54 months, 74 patients were recruited. The cumulative incidence of HC was 22%. Among 15 patients prospectively monitored for BK viruria and viraemia, four patients developed HC of grade > or =II. This group, which had two consecutive BK positive samples, showed a sensitivity of 100%, a specificity of 82%, a positive predictive value of 67%, and negative predictive value of 100% for developing HC. Analysed by a receiver-operator characteristic curve (ROC), a urine BK load >9 x 10(6) genomic copies/ml had a sensitivity of 95% and specificity of 90%; while a blood BK load >1 x 10(3) genomic copies/ml had a sensitivity of 40% and a specificity of 93% for HC, respectively. In univariate analysis, BK positivity was the only factor significantly associated with HC. After a median follow-up of 1.8 years, patients with HC showed a lower overall survival, 40 vs 65%, P 0.01, and a lower event-free survival, 42 vs 62%, P 0.03, compared to patients without HC. We conclude that BK detection in urine and/or plasma is a specific predictor for developing HC.