The DST/NRF Centre of Excellence in Epidemiological Modelling and Analysis (SACEMA), Stellenbosch University, Stellenbosch, South Africa.
Division of Medical Virology, Department of Pathology, Stellenbosch University, Cape Town, South Africa.
BMC Infect Dis. 2019 Feb 11;19(1):136. doi: 10.1186/s12879-019-3767-z.
Access to qualitative HIV PCRs for early infant diagnosis (EID) is restricted in resource-limited settings due to cost. We hypothesised that pooling of dried blood spots (DBS), defined as combining multiple patient samples in a single test with subsequent individual testing of positive pools, would be cost saving while retaining clinical accuracy compared to individual patient testing.
Cost savings: A model was developed to simulate reagent and consumable cost saving of pooled compared to individual sample testing. Daily sample/result data of a public health laboratory in South Africa were used to illustrate outputs from the model. Samples were randomly allocated to pools and the process was repeated 1000 times to measure variation in estimates due to this stochasticity. Clinical accuracy: 1170 patient samples were tested using the Roche CAP/CTM Qual assay in pools of five 50 μl DBS. Negative pools comprised DBS previously tested in single reactions; positive pools included 1 positive sample.
Pooling would have saved 64% of laboratory costs in 2015. The model is published as an R-based web tool, into which the user enters sample/positivity estimates and workflow management parameters to obtain cost saving estimates at an optimal pool size. Sensitivity of pooled testing was 98.8% overall; 100% for strongly reactive pools. One pool tested false positive which would not impact clinical specificity as individual patient testing is performed prior to reporting.
Pooled PCR testing for EID remains accurate and dramatically reduces costs in settings with moderate to low prevalence rates and sufficient sample numbers.
由于成本原因，资源有限的环境中获得用于早期婴儿诊断（EID）的定性 HIV PCR 的途径受到限制。我们假设，将干血斑（DBS）进行合并（即将多个患者样本合并在一个测试中，随后对阳性池进行单独测试），与对每个患者样本进行单独测试相比，在保留临床准确性的同时可以节省成本。
成本节约：建立了一个模型来模拟与单独样本测试相比，合并测试的试剂和耗材成本节约。使用南非一家公共卫生实验室的每日样本/结果数据来说明模型的输出。将样本随机分配到池中，并重复该过程 1000 次，以衡量由于这种随机性而导致的估计值的变化。临床准确性：使用罗氏 CAP/CTM Qual 测定法对 1170 个患者样本进行了五份 50μl DBS 的合并检测。阴性池由先前在单个反应中测试的 DBS 组成；阳性池包括 1 个阳性样本。
2015 年，合并检测将节省 64%的实验室成本。该模型已作为基于 R 的网络工具发布，用户可以在其中输入样本/阳性率估计值和工作流程管理参数，以获得在最佳池大小下的成本节约估计值。合并检测的敏感性总体为 98.8%；强反应性池的敏感性为 100%。一个池检测出假阳性，但由于在报告前进行了单个患者测试，因此不会影响临床特异性。
在流行率和样本数量适中或较低的环境中，用于 EID 的合并 PCR 检测仍然准确，并可大大降低成本。
