Ramachandran Anu, Noble Jeanne, Deucher Anne, Miller Steve, Tang Patrick Wai, Wang Ralph C
Department of Emergency Medicine University of California San Francisco San Francisco California USA.
Department of Laboratory Medicine University of California San Francisco San Francisco California USA.
J Am Coll Emerg Physicians Open. 2021 Dec 29;2(6):e12592. doi: 10.1002/emp2.12592. eCollection 2021 Dec.
We sought to evaluate the test characteristics of Abbott ID-Now as a screening tool compared to polymerase chain reaction (PCR) testing for identification of COVID in an asymptomatic emergency department population.
We performed a prospective study enrolling a convenience sample of asymptomatic patients presenting to a single academic emergency department (ED) who received simultaneous testing with ID-Now and PCR per standardized ED protocols. Sensitivity, specificity, and positive and negative predictive value (PPV, NPV) of ID-Now were calculated compared to PCR. Stratified analysis by cycle threshold (Ct) values was also performed, defined as high viral load (Ct < 33) and low viral load (Ct ≥ 33).
A total of 3121 patients were enrolled, of whom 2895 had valid results for ID-Now and PCR. COVID prevalence was 2.6%. ID-Now had a sensitivity of 85.1% (95% CI 75.9% to 92.7%) and a specificity of 99.7% (99.5% to 99.9%). PPV and NPV were high at 87.5% (83.1% to 96.1%) and 99.6% (99.3% to 99.8%). Stratified analysis by low and high Ct values demonstrated reduction in sensitivity in patients with low viral loads: 91.7% (81.6% to 97.2%) in low Ct value patients versus 58.3% (27.7% to 84.8%) in high Ct value patients.
ID-Now had excellent performance in asymptomatic ED patients with a low rate of false positives. Cycle threshold analysis suggests a relationship between viral load and ID-Now sensitivity. Given its speed and performance in this population, ID-Now should be considered an excellent tool to support clinical decision-making in ED populations.
我们试图评估与聚合酶链反应（PCR）检测相比，雅培ID-Now作为一种筛查工具在无症状急诊科人群中识别新型冠状病毒肺炎（COVID）的检测特征。
我们进行了一项前瞻性研究，纳入了到单一学术急诊科就诊的无症状患者的便利样本，这些患者按照标准化的急诊科方案同时接受ID-Now和PCR检测。将ID-Now与PCR相比，计算其敏感性、特异性以及阳性和阴性预测值（PPV、NPV）。还按循环阈值（Ct）值进行了分层分析，Ct值<33定义为高病毒载量，Ct值≥33定义为低病毒载量。
共纳入3121例患者，其中2895例ID-Now和PCR检测结果有效。新型冠状病毒肺炎患病率为2.6%。ID-Now的敏感性为85.1%（95%置信区间75.9%至92.7%），特异性为99.7%（99.5%至99.9%）。PPV和NPV较高，分别为87.5%（83.1%至96.1%）和99.6%（99.3%至99.8%）。按低和高Ct值进行的分层分析表明，低病毒载量患者的敏感性降低：低Ct值患者为91.7%（81.6%至97.2%），高Ct值患者为58.3%（27.7%至84.8%）。
ID-Now在无症状急诊科患者中表现出色，假阳性率低。循环阈值分析表明病毒载量与ID-Now敏感性之间存在关联。鉴于其在该人群中的速度和性能，ID-Now应被视为支持急诊科人群临床决策的优秀工具。
