Pardo Lledias J, Ayarza L, González-García P, Salmón González Z, Calvo Montes J, Gozalo Marguello M, Hernández Hernández J L, Olmos Martínez J M
Javier Pardo Lledias. Servicio de Medicina Interna. Hospital Universitario Marqués de Valdecilla-IDIVAL. Santander. C/ Avenida Valdecilla 25; 39008. Santander Cantabria, Spain.
Rev Esp Quimioter. 2020 Dec;33(6):410-414. doi: 10.37201/req/080.2020. Epub 2020 Sep 11.
The diagnosis of SARS-CoV-2 infection presents some limitations. RT-PCR in nasopharyngeal swabs is considered the gold standard for the diagnosis, although it can have false negative results. We aimed to analyze the accuracy of repeating nasopharyngeal swabs based on different clinical probabilities.
Retrospective observational study of the first patients admitted to a two COVID Internal Medicine wards at the University Hospital Marqués de Valdecilla, Santander, from March to April 2020. RT-PCR targering E, N, RdRP and ORFab1 genes and antibody tests detecting IgG.
A total of 145 hospitalized patients with suspected SARS-Cov2 infection were admitted and in 98 (67.5%) diagnosis was confirmed. The independent predictive variables for SARS-CoV-2 infection were: epidemiological contact, clinical presentation as pneumonia, absence of pneumonia in the last year, onset of symptoms > 7 days, two or more of the following symptoms -dyspnea, cough or fever- and serum lactate dehydrogenase levels >350 U/L (p<0.05). A score based on these variables yielded an AUC-ROC of 0.89 (CI95%, 0.831-0.946; p<0.001). The accuracy of the first nasopharyngeal swabs was 54.9%. Repeating nasopharyngeal swabs two or three times allows to detect an additional 16% of positive cases. The overall accuracy of successive RT-PCR tests in patients with low pre-test probability was <5%.
We have defined a pre-test probability score based on epidemiological and clinical data with a high accuracy for diagnosis of SARS-CoV-2. Repeating nasopharyngeal swabs avoids sampling errors, but only in medium of high probability pre-test clinical scenarios.
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）感染的诊断存在一些局限性。鼻咽拭子的逆转录聚合酶链反应（RT-PCR）虽被视为诊断的金标准，但可能出现假阴性结果。我们旨在分析基于不同临床概率重复进行鼻咽拭子检测的准确性。
对2020年3月至4月在桑坦德瓦尔迪西利亚侯爵大学医院两个新冠内科病房收治的首批患者进行回顾性观察研究。采用针对E、N、RdRP和ORFab1基因的RT-PCR以及检测IgG的抗体检测。
共收治145例疑似SARS-CoV-2感染的住院患者，其中98例（67.5%）确诊。SARS-CoV-2感染的独立预测变量为：流行病学接触史、肺炎临床表现、过去一年无肺炎病史、症状出现>7天、以下两种或更多症状——呼吸困难、咳嗽或发热——以及血清乳酸脱氢酶水平>350 U/L（p<0.05）。基于这些变量的评分得出曲线下面积（AUC-ROC）为0.89（95%置信区间，0.831-0.946；p<0.001）。首次鼻咽拭子检测的准确性为54.9%。重复进行两次或三次鼻咽拭子检测可额外检测出16%的阳性病例。检测前概率较低的患者连续进行RT-PCR检测的总体准确性<5%。
我们基于流行病学和临床数据定义了一个检测前概率评分，对SARS-CoV-2诊断具有较高准确性。重复进行鼻咽拭子检测可避免采样误差，但仅适用于检测前临床概率为中高的情况。
