Department of Pathology, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran.
Iran J Kidney Dis. 2022 Nov;16(6):368-373.
BK virus nephropathy (BKVN) is an important complication of kidney transplantation and kidney biopsy remains the gold standard for its diagnosis. Urine/serum polymerase chain reaction (PCR) is a more sensitive diagnostic method, although it has some potential limitations.
This study enrolled all kidney transplant recipients who underwent kidney transplant biopsy, collected from three medical centers. Urine and serum PCR results of the patients were also collected from the molecular laboratories. The cut-off value for positive viral DNA load in serum and urine were > 104 and > 107 copies/mL, respectively. Sensitivity, specifity, positive and negative predictive values (PPV, NPV) and cut off values for PCR results were compared with pathologic diagnosis among laboratories.
Among 369 biopsy samples, 33 (8.9%) had definite diagnosis of BKVN. PCR results were available for 138 cases. Three patients with definite BKVN had negative PCR results. In 22 patients, PCR was positive without evidence of BKVN. The overall sensitivity, specificity, PPV and NPV of PCR for detecting BKVN, based on a unique cut-off value, were 88, 81, 51, and 97%; respectively. The overall accuracy of PCR in all laboratories was high (82 to 86%), however significant inter-laboratory differences in sensitivity and specificity was found . A 2-log difference in threshold value for positive results was observed in one laboratory.
PCR may show a significant variability between different laboratories. Interpretation of PCR results using a single cut-off value for all laboratories, may decrease the sensitivity for the diagnosis and screening of BKVN. DOI: 10.52547/ijkd.7143.
BK 病毒肾病（BKVN）是肾移植的重要并发症，肾活检仍是其诊断的金标准。尿/血清聚合酶链反应（PCR）是一种更敏感的诊断方法，尽管它有一些潜在的局限性。
本研究纳入了来自三个医疗中心的所有接受肾移植活检的肾移植受者。还从分子实验室收集了患者的尿和血清 PCR 结果。血清和尿液中病毒 DNA 载量阳性的截断值分别为>104 和>107 拷贝/ml。在实验室之间，比较了 PCR 结果与病理诊断的敏感性、特异性、阳性预测值（PPV）、阴性预测值（NPV）和截断值。
在 369 个活检样本中，33 例（8.9%）有明确的 BKVN 诊断。有 138 例可获得 PCR 结果。3 例确诊为 BKVN 的患者 PCR 结果为阴性。在 22 例 PCR 阳性但无 BKVN 证据的患者中。基于独特的截断值，PCR 检测 BKVN 的总体敏感性、特异性、PPV 和 NPV 分别为 88%、81%、51%和 97%。所有实验室的 PCR 总体准确性均较高（82%至 86%），但在敏感性和特异性方面存在显著的实验室间差异。一个实验室的阳性结果阈值相差 2 个对数。
PCR 可能在不同实验室之间表现出显著的差异。使用所有实验室的单一截断值来解释 PCR 结果，可能会降低 BKVN 的诊断和筛查的敏感性。DOI：10.52547/ijkd.7143.
