Madden Kathleen, Janitell Charles, Sower Daniel, Yang Shangxin
Department of Pathology, University of New Mexico, Albuquerque, NM, USA.
TriCore Reference Laboratories, Albuquerque, NM, USA.
Transpl Infect Dis. 2018 Oct;20(5):e12952. doi: 10.1111/tid.12952. Epub 2018 Jun 25.
BK virus (BKPyV)-associated nephropathy (BKPyVAN) may affect up to 10% of renal transplant recipients, causing graft failure in the absence of intervention. The dilemma in monitoring BKPyVAN in renal transplant patients has been that only testing urine BK viral load represents higher sensitivity (earlier detection) but lower specificity, while testing plasma BK viral load represents lower sensitivity (later detection) but higher specificity. However, blindly testing both urine and plasma inevitably contributes to unnecessary medical cost. We analyzed 1030 paired urine and plasma BKPyV viral load results and identified a reliable urine BKPyV viral load cutoff (4.0 log IU/mL) that can predict BKPyV viremia with 99.7% negative predictive value (NPV). We propose a cost-effective screening algorithm to first only monitor the urine BKPyV levels until the viral load reaches 4.0 log IU/mL, and then only monitor plasma with higher frequency. This approach ensures 98.7% sensitivity of catching the earliest BKPyV viremia onset, and 100% sensitivity of detecting the critical BKPyV viremia. In addition, we identified a urine BKPyV viral load cutoff of 6.7 log IU/mL as predictive of critical BKPyV viremia (defined as plasma viral load >4.0 log IU/mL) with 100% sensitivity and 100% NPV.
BK病毒（BKPyV）相关性肾病（BKPyVAN）可能影响高达10%的肾移植受者，如不进行干预可导致移植肾失功。监测肾移植患者BKPyVAN的困境在于，仅检测尿液BK病毒载量灵敏度较高（检测较早）但特异性较低，而检测血浆BK病毒载量灵敏度较低（检测较晚）但特异性较高。然而，盲目同时检测尿液和血浆不可避免地会导致不必要的医疗费用。我们分析了1030对尿液和血浆BKPyV病毒载量结果，确定了一个可靠的尿液BKPyV病毒载量临界值（4.0 log IU/mL），其预测BKPyV病毒血症的阴性预测值（NPV）为99.7%。我们提出了一种具有成本效益的筛查算法，首先仅监测尿液BKPyV水平，直至病毒载量达到4.0 log IU/mL，然后仅更频繁地监测血浆。这种方法确保捕捉到最早BKPyV病毒血症发作的灵敏度为98.7%，检测临界BKPyV病毒血症的灵敏度为100%。此外，我们确定尿液BKPyV病毒载量临界值为6.7 log IU/mL可预测临界BKPyV病毒血症（定义为血浆病毒载量>4.0 log IU/mL），灵敏度和NPV均为100%。
