Microbiology Unit, ASST Ovest Milanese, Hospital of Legnano, Legnano, Milan, Italy.
J Med Virol. 2017 Oct;89(10):1817-1822. doi: 10.1002/jmv.24831. Epub 2017 May 23.
Some international guidelines recommend evaluating the need to confirm positive anti-hepatitis C virus (HCV) antibody screening results by means of a more specific antibody or molecular biology test on the basis of a screening threshold value (such as the sample signal/cut-off ratio) that can predict the positivity of additional antibody testing in at least 95% of cases. The aim of this study was to determine the threshold value of the DiaSorin LIAISON XL chemiluminescence test. Two hundred and twenty-eight routine laboratory samples that were chemiluminescence positive for anti-HCV antibodies but had different signal/cut-off ratios were assayed using immunoblotting, which indicated that 155 (68.0%) were positive, 40 (17.5%) were negative, and 33 (14.5%) were indeterminate. When the samples were divided on the basis of their signal/cut-off ratios, 95.5% of the samples with a ratio of ≥3.5 were positive as against 74.1% of the positive or indeterminate samples with a ratio of <3.5. Statistical analysis using Youden's index and a receiver operating characteristic curve showed that the optimum cut-off value was 3.65. These findings indicate that, when using the LIAISON XL system for anti-HCV antibody screening, a signal/cut-off ratio of ≥3.65 makes further confirmatory tests unnecessary.
一些国际指南建议，根据能够预测至少 95%的额外抗体检测阳性的筛选阈值（例如样本信号/临界比值），通过更具特异性的抗体或分子生物学检测来评估确认抗丙型肝炎病毒（HCV）抗体阳性筛查结果的必要性。本研究旨在确定 DiaSorin LIAISON XL 化学发光检测的阈值。对 228 例化学发光法抗 HCV 抗体阳性但信号/临界比值不同的常规实验室样本进行免疫印迹检测，结果显示 155 例（68.0%）为阳性，40 例（17.5%）为阴性，33 例（14.5%）为不确定。根据信号/临界比值对样本进行分组时，比值≥3.5 的样本中 95.5%为阳性，而比值<3.5 的阳性或不确定样本中仅 74.1%为阳性。使用约登指数和受试者工作特征曲线进行统计学分析表明，最佳临界值为 3.65。这些发现表明，在使用 LIAISON XL 系统进行抗 HCV 抗体筛查时，信号/临界比值≥3.65 使得进一步的确认检测变得不必要。
