【Cochrane简语概要】在医疗机构就诊时进行的快速检测诊断COVID-19的准确性如何？

为什么这个问题很重要？

COVID-19的疑似患者需要迅速了解自己是否被感染，以便进行自我隔离，接受治疗并告知密切的接触者。目前，可以通过从鼻子和咽喉中采集的样本进行实验室检测来确诊COVID-19感染。称为RT-PCR的实验室检测需要专业的设备，可能需要多次就诊，通常需要至少24小时才能得出结果。

快速即时检测可以在“等待期”内提供结果，理想的情况是在提供样本后的两个小时之内。这可以帮助人们及早隔离并减少感染的传播。

我们想知道什么？

我们对两种快速即时检测，即抗原和分子检测感兴趣。抗原检测通常使用一次性设备来鉴定病毒上的蛋白质。分子检测使用小型便携式或台式设备检测病毒的遗传物质。两者都与RT-PCR检测使用相同的鼻或咽喉部样本。

我们想知道快速即时抗原和分子检测是否足够准确以代替RT-PCR来诊断感染，或者筛选出结果是阴性的人进行进一步检测。

我们做了什么？

我们检索了比较快速即时检测与RT-PCR检测在检测当前COVID-19感染方面准确性的研究。研究可以是与参考标准测试相比的任何快速的抗原或分子即时检测。参考标准是诊断感染的最佳方法。我们考虑将RT-PCR检测结果与COVID-19的临床诊断结果作为参考。人们可以在医院或社区接受检测。研究可以测试有或无症状的人。

检测必须使用最少的设备，在没有被样本感染风险的情况下安全进行，并在采集样本后两小时内获得结果。测试可以在小型实验室或患者所在的任何地方（在初级保健机构、急救机构或医院）使用。

研究如何评估诊断测试的准确性？

研究通过快速即时检测对受试者进行了测试。所有研究均通过RT-PCR将受试者分为已感染和未感染COVID-19。研究还确定了与RT-PCR相比，即时检测结果中的假阳性和假阴性错误。当无COVID-19感染时，假阳性的检测错误地检出COVID-19感染，可能导致不必要的自我隔离和进一步检测。当存在COVID-19感染时，假阴性的检测造成的漏诊可能延迟自我隔离和治疗以及使感染扩散。

我们发现了什么

我们共检索到了18项研究。十项研究在北美进行，四项在欧洲，两项在南美，一项在中国，还有一项在多个国家开展。

九项研究特意纳入了高比例的COVID-19确诊者或只纳入COVID-19患者。十四项研究没有提供任何关于样本提供者的信息，12项研究没有提供任何关于人们在哪里接受检测的信息。

没有研究报告纳入无症状者的样本。

主要结果

五项研究报告了对五种不同抗原测试的八项评估。总的来说，不同的抗原测试在检测COVID-19感染的准确度上有很大差异。在不到1%的样本中，检测给出了假阳性结果。

对四种不同分子测试的十三项评估正确地检测出平均95％的COVID-19感染样本。大约1％的样品给出了假阳性结果。

如果有1000人进行了分子检测，而其中100人（10％）确实感染了COVID-19：

- 105人的COVID-19检测结果呈阳性。其中，有10人（10％）没有感染COVID-19（假阳性结果）。

- 895人的COVID-19检测结果为阴性。其中，有5人（1％）实际感染了COVID-19（假阴性结果）。

我们注意到在两个最常被评估的分子测试之间，COVID-19检测结果存在很大差异。

本系统综述结果的可信度如何？

我们对证据的信心有限。

- 四分之三的研究没有按照制造商的说明进行，所以如果他们照做了，也可能会得到不同的结果。

- 通常，研究没有使用最可靠的方法，或者没有报告足够的信息供我们判断他们使用的方法。这可能会影响检测的准确性，但无法确定有多大的影响。

- 四分之一的研究以“预印本”的形式提前在线发表，并纳入在本系统综述中。预印本未经过发表研究的常规严格检查，所以我们不确定它们的可靠性。

本系统综述的意义是什么？

研究几乎没有提供有关受试者的信息，因此无法确定结果是否可以应用于无症状，轻症感染者或COVID-19住院患者。准确的快速检测将有可能筛选要进行RT-PCR的人，或者将其用于无法使用RT-PCR的人。但是，目前的证据还不够充分，迫切需要进行更多的研究才能确定这些测试是否足以在实践中使用。

本系统综述的时效性如何?

本系统综述纳入了截止至2020年5月25日发表的文献。由于该领域有许多新研究正在发表，因此我们将很快更新本系统综述

（图片来源于Cochrane.org）

结论: 

本综述找到了主要基于残留的实验室样本的，对SARS-CoV-2感染的即时检测的早期评估。目前，这些结果的适用性有限，因为我们不确定在临床实践中是否会根据COVID-19的症状、症状持续时间或在无症状人群中进行同样的检测。快速检测有可能用于提示是否需要进一步RT-PCR检测，从而允许更早地发现阳性感染者，但目前的证据还不足以确定其在临床实践中的有用性。

迫切需要对临床相关环境中COVID-19感染的快速检测进行前瞻性和比较性评估。研究应招募一系列符合条件的受试者，包括因出现症状而来接受检测的受试者以及可能与确诊病例接触过的无症状者。研究应清楚地描述症状，并记录从症状出现或暴露后的时间。即时检测必须根据制造商使用说明、在医疗点进行。今后的研究报告应符合诊断准确性研究报告规范 (Standards for Reporting of Diagnostic Accuracy, STARD) 指南。

译者：赵洁；审校：刘旭，香港中文大学那打素护理学院；编辑排版：郑偌祥、张晓雯，北京中医药大学循证医学中心

相关文章链接

【Cochrane Plain Language Summary】How accurate are rapid tests, performed during a health-care visit (point-of-care), for diagnosing COVID-19?

Why is this question important?

People with suspected COVID-19 need to know quickly whether they are infected, so that they can self-isolate, receive treatment, and inform close contacts. Currently, COVID-19 infection is confirmed by sending away samples, taken from the nose and throat, for laboratory testing. The laboratory test, called RT-PCR, requires specialist equipment, may require repeat healthcare visits, and typically takes at least 24 hours to produce a result.

Rapid point-of-care tests can provide a result ‘while you wait’, ideally within two hours of providing a sample. This could help people isolate early and reduce the spread of infection.

What did we want to find out?

We were interested in two types of rapid point-of-care tests, antigen and molecular tests. Antigen tests identify proteins on the virus, often using disposable devices. Molecular tests detect the virus’s genetic material, using small portable or table-top devices. Both test the same nose or throat samples as RT-PCR tests.

We wanted to know whether rapid point-of-care antigen and molecular tests are accurate enough to replace RT-PCR for diagnosing infection, or to select people for further testing if they have a negative result.

What did we do?

We looked for studies that measured the accuracy of rapid point-of-care tests compared with RT-PCR tests to detect current COVID-19 infection. Studies could assess any rapid antigen or molecular point-of-care test, compared with a reference standard test. The reference standard is the best available method for diagnosing the infection; we considered RT-PCR test results and clinically defined COVID-19 as reference tests. People could be tested in hospital or the community. Studies could test people with or without symptoms.

Tests had to use minimal equipment, be performed safely without risking infection from the sample, and have results available within two hours of the sample being collected. Tests could be used in small laboratories or wherever the patient is (in primary care, urgent care facilities, or in hospital).

How did studies assess diagnostic test accuracy?

Studies tested participants with the rapid point-of-care tests. Participants were classified as known to have – and not to have - COVID-19, by RT-PCR in all studies. Studies then identified false positive and false negative errors in the point-of-care test results, compared to RT-PCR. False positive tests incorrectly identified COVID-19 when it was not present, potentially leading to unnecessary self-isolation and further testing. False negatives missed COVID-19 when it was present, risking delayed self-isolation and treatment, and spread of infection.

What we found

We found 18 relevant studies. Ten studies took place in North America, four in Europe, two in South America, one in China and one in multiple countries.

Nine studies deliberately included a high percentage of people with confirmed COVID-19 or included only people with COVID-19. Fourteen studies did not provide any information about the people providing the samples for testing and 12 did not provide any information about where people were tested.

None of the studies reported includedsamples from people without symptoms.

Main results

Five studies reported eight evaluations of five different antigen tests. Overall, there was considerable variation between the results of the antigen tests in how well they detected COVID-19 infection. Tests gave false positive results in less than 1% of samples.

Thirteen evaluations of four different molecular tests correctly detected an average of 95% of samples with COVID-19 infection. Around 1% of samples gave false positive results.

If 1000 people had molecular tests, and 100 (10%) of them really had COVID-19:

- 105 people would test positive for COVID-19. Of these, 10 people (10%) would not have COVID-19 (false positive result).

- 895 people would test negative for COVID-19. Of these, 5 people (1%) would actually have COVID-19 (false negative result).

We noted a large difference in COVID-19 detection between the two most commonly evaluated molecular tests.

How reliable were the results of the studies?

Our confidence in the evidence is limited.

- Three-quarters of studies did not follow the test manufacturers’ instructions, so may have found different results if they had.

- Often, studies did not use the most reliable methods or did not report enough information for us to judge their methods. This may have affected estimates of test accuracy, but it is impossible to identify by how much.

- A quarter of studies were published early online as ‘preprints’ and are included in the review. Preprints do not undergo the normal rigorous checks of published studies, so we are uncertain how reliable they are.

What are the implications of this review?

Studies provided little information about their participants, so it is not possible to tell if the results can be applied to people with no symptoms, mild symptoms, or who were hospitalised with COVID-19. Accurate rapid tests would have the potential to select people for RT-PCR testing or to be used where RT-PCR is not available. However, the evidence currently is not strong enough and more studies are urgently needed to be able to say if these tests are good enough to be used in practice.

How up-to-date is this review?

This review includes evidence published up to 25 May 2020. Because new research is being published in this field, we will update this review soon.

www.cochrane.org

Authors' conclusions: 

This review identifies early-stage evaluations of point-of-care tests for detecting SARS-CoV-2 infection, largely based on remnant laboratory samples. The findings currently have limited applicability, as we are uncertain whether tests will perform in the same way in clinical practice, and according to symptoms of COVID-19, duration of symptoms, or in asymptomatic people. Rapid tests have the potential to be used to inform triage of RT-PCR use, allowing earlier detection of those testing positive, but the evidence currently is not strong enough to determine how useful they are in clinical practice.

Prospective and comparative evaluations of rapid tests for COVID-19 infection in clinically relevant settings are urgently needed. Studies should recruit consecutive series of eligible participants, including both those presenting for testing due to symptoms and asymptomatic people who may have come into contact with confirmed cases. Studies should clearly describe symptomatic status and document time from symptom onset or time since exposure. Point-of-care tests must be conducted on samples according to manufacturer instructions for use and be conducted at the point of care. Any future research study report should conform to the Standards for Reporting of Diagnostic Accuracy (STARD) guideline.

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