Austrian Association for Quality Assurance and Standardization of Medical and Diagnostic Tests (ÖQUASTA), Vienna, Austria.
Center for Virology, Medical University of Vienna, Vienna, Austria.
Clin Chem Lab Med. 2022 May 23;60(8):1308-1312. doi: 10.1515/cclm-2022-0263. Print 2022 Jul 26.
Results of earlier external quality assessment (EQA) rounds suggested remarkable differences in the sensitivity of SARS-CoV PCR assays. Although the test systems are intended to detect SARS-CoV-2 in individual samples, screening is often applied to sample pools to increase efficiency and decrease costs. However, it is unknown to what extent these tests actually meet the manufacturer's specifications for sensitivity and how they perform when testing sample pools.
The sensitivity of assays in routine use was evaluated with a panel of positive samples in a round of a SARS-CoV-2 virus genome detection EQA scheme. The panel consisted of samples at or near the lower limit of detection ("weakly positive"). Laboratories that routinely test sample pools were asked to also analyze the pooled EQA samples according to their usual pool size and dilution method.
All participants could detect a highly positive patient-derived sample (>10 copies/mL). Most (96%) of the test systems could detect at least 1,000 copies/mL, meeting the minimum acceptable benchmark, and many (94%) detected the vRNA in a sample with lower concentration (500 copies/mL). The false negative ratio increased to 16 and 26% for samples with 100 and 50 copies/mL, respectively.
The performance of most assays met or exceeded their specification on sensitivity. If assays are to be used to analyze sample pools, the sensitivity of the assay and the number of pooled samples must be balanced.
早期的外部质量评估（EQA）结果表明，SARS-CoV PCR 检测方法的灵敏度存在显著差异。尽管这些检测系统旨在检测个体样本中的 SARS-CoV-2，但通常会对样本池进行筛查，以提高效率并降低成本。然而，尚不清楚这些测试在多大程度上实际符合制造商规定的灵敏度要求，以及它们在测试样本池时的性能如何。
在 SARS-CoV-2 病毒基因组检测 EQA 方案的一轮中，使用一组阳性样本评估常规使用的检测方法的灵敏度。该样本组由接近检测下限的弱阳性样本组成。要求常规测试样本池的实验室按照其通常的样本池大小和稀释方法分析 EQA 样本池。
所有参与者均能检测到高度阳性的患者来源样本（>10 拷贝/mL）。大多数（96%）检测系统可检测至少 1000 拷贝/mL，符合可接受的最低基准，许多（94%）可检测出浓度较低（500 拷贝/mL）的样本中的 vRNA。对于 100 拷贝/mL 和 50 拷贝/mL 的样本，假阴性率分别增加到 16%和 26%。
大多数检测方法的性能符合或超过其灵敏度规格。如果要使用检测方法分析样本池，则必须平衡检测方法的灵敏度和样本池的数量。
