Objective: To explore the clinical value of SARS-CoV2 IgM and IgG antibodies in the diagnosis of COVID-19 in suspected cases by likelihood ratio.
Methods: By reinterpreting data from a previous study, the positive likelihood ratio of IgM and IgG antibodies in COVID-19 pneumonia diagnosis was calculated, and the posterior probability of IgM and IgG antibodies and their tandem detection was calculated finally.
Results: The positive likelihood ratios of single IgM and IgG antibodies were 18.50 and 12.65, respectively, and the posterior probabilities were 90.18% and 86.26%, respectively. However, the posterior probability of the two antibody-tandem test was 99.15%, which could give clinicians more quantitative confidence in the diagnosis of COVID-19 in suspected cases. According to the results of this study, combining the advantages and disadvantages of nucleic acid testing and antibody detection, a feasible clinical path was found for clinicians to diagnose COVID-19 pneumonia from suspected cases.
Conclusion: For suspected cases, IgM- and IgG-antibody tests should first be done at the same time. If all antibody tests are positive, COVID-19 pneumonia could be confirmed. If not, nucleic acid detection (once or more) should be carried out, and in extreme cases high-throughput viral genome sequencing is required.

Keywords: COVID-19, SARS-CoV2, positive likelihood ratio, posterior probability, antibody test, nucleic acid test, clinical pathway


中文翻译：

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SARS-CoV2 IgM 和 IgG 抗体在诊断 COVID-19 疑似病例中的临床价值

目的：探讨似然比法检测SARS-CoV2 IgM和IgG抗体在疑似病例COVID-19诊断中的临床价值。
方法：通过重新解读既往研究数据，计算IgM和IgG抗体在COVID-19肺炎诊断中的阳性似然比，并最终计算IgM和IgG抗体及其串联检测的后验概率。
结果：单项IgM和IgG抗体阳性似然比分别为18.50和12.65，后验概率分别为90.18%和86.26%。然而，两种抗体串联检测的后验概率为99.15%，这可以让临床医生对疑似病例的COVID-19诊断更有定量信心。根据本研究结果，结合核酸检测和抗体检测的优缺点，为临床医生从疑似病例中诊断COVID-19肺炎找到了一条可行的临床路径。
结论：对于疑似病例，首先应同时进行IgM抗体和IgG抗体检测。如果所有抗体检测均呈阳性，则可确诊 COVID-19 肺炎。如果没有，则应进行核酸检测（一次或多次），极端情况下需要进行高通量病毒基因组测序。

关键词： COVID-19、SARS-CoV2、阳性似然比、后验概率、抗体检测、核酸检测、临床路径