key: cord-1036936-znrjdf4c
authors: Gottlieb, Michael; Jay, Alexander; Mogni, Benjamin
title: What is the diagnostic accuracy of chest radiography, ultrasound, and computed tomography for COVID-19?
date: 2021-05-14
journal: Ann Emerg Med
DOI: 10.1016/j.annemergmed.2021.05.011
sha: 52f90df1f8624209c3e8f1fcc2fcfd7cc862e001
doc_id: 1036936
cord_uid: znrjdf4c

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What is the diagnostic accuracy of chest radiography, ultrasound, and computed tomography for COVID-19?

Chest radiography is a reasonable initial test with moderate sensitivity and specificity. Chest computed tomography and lung ultrasound have greater sensitivity and can be considered when the initial chest radiograph is non-diagnostic.

Methods:

The authors searched PubMed, Embase, the CDC Library on COVID-19 research articles database, and preprints indexed in bioRxiv and medRxiv through September 30th, 2020. The authors also searched ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform.

Two authors independently screened articles for inclusion, with discrepancies resolved by consensus with a third reviewer. The authors included all study designs except for case-control that reported on test accuracy of chest radiography, lung ultrasound, or chest computed tomography (CT). Study participants included humans suspected of having COVID-19 (regardless of age). The reference standard was a positive reverse transcription polymerase chain J o u r n a l P r e -p r o o f reaction (RT-PCR) COVID-19 result (from any manufacturer and using any sample type), positive WHO criteria for COVID-19, positive China CDC criteria for COVID-19, positive serology for SARS-CoV-2 antibodies with concurrent symptoms, or positive findings using study-specific criteria. There were no language restrictions.

Two review authors independently extracted data and assessed methodological quality, with discrepancies resolved by consensus with a third reviewer. Risk of bias and applicability concerns were assessed using the QUADAS-2 domain list. 1 Data was analyzed using a bivariate model to account for within-and between-study variance, and the correlation between sensitivity and specificity across studies. Heterogeneity was investigated through visual inspection of forest plots and summary receiver operating characteristics plots. The authors did not assess for publication bias. 

The researchers identified a total of 4,734 studies, with 51 studies (n=19,755) being selected for inclusion. Out of the total cohort of studied patients, 10,155 (51.4%) had a final diagnosis of COVID-19. All studies used RT-PCR as the reference standard. Images were read by attending radiologists in 39 studies, radiology residents in 2 studies, and both radiology attending and residents 1 study. Eight studies did not report the level of training for the party responsible for reading images. The majority of studies were conducted in Europe (N=33), with the remainder conducted in Asia (N=13), North American (N=3), and South America (N=2). Chest CT and lung ultrasound both had moderate sensitivity, which were higher than chest radiography (Table) . Chest CT had the highest specificity, while lung ultrasound had the lowest specificity.

As of April 2021, there have been over 138 million confirmed cases of COVID-19 with nearly 3 million deaths worldwide. 2 Symptoms can vary significantly across patients infected with COVID-19 and testing has not been universally available. 3, 4 Moreover, while rapid testing can provide results within minutes, RT-PCR typically has a longer turnaround time, limiting the ability to utilize the information as rapidly in real-time. Therefore, imaging offers an alternative for diagnosing COVID-19 pulmonary involvement in the acute care setting.

This systematic review found that chest radiography, lung ultrasound, and chest CT all had moderate sensitivity, with lower sensitivity for chest radiography and lower specificity for ultrasound. 5 The authors also highlight the importance of considering the pre-test probability and J o u r n a l P r e -p r o o f prevalence of COVID-19 when interpreting these findings. With a prevalence of 5%, the false negative rate would be 0.6% for CT, 0.7% for ultrasound, and 1% for radiography, whereas with a prevalence of 50%, the false negative rate would increase to 6% for CT, 7% for ultrasound, and 10% for radiography. This review has several limitations. First, the study populations were clinically heterogenous, including a mix of pediatric and adult patients, as well as severity of illness and comorbidities (e.g., heart failure, end-stage renal disease). The study prevalence also varied significantly, ranging from 5% to 90%. The gold standard was RT-PCR in all studies, but the specific test, sample fluid, and frequency (i.e., repeat testing if negative) varied across studies. There were also differences in the type of chest radiograph (e.g., single view versus two views) and type of CT scanner (e.g., resolution, use of contrast). Moreover, there were differences in the imaging criteria used and who was performing the interpretations (e.g., resident vs attending physician, specialty). The ultrasound data were substantially more limited with only a few studies and small sample sizes. In fact, more recent data have suggested that ultrasound may be more accurate than RT-PCR. 6 Finally, there was limited description of the sonographer training or experience, which is critical given the operator-dependent nature of this skill.

This is a clinical synopsis, a regular feature of the Annals' Systematic Review Snapshot (SRS) 

QUADAS-2: a revised tool for the quality assessment of diagnostic accuracy studies

The prevalence of symptoms in 24,410 adults infected by the novel coronavirus (SARS-CoV-2; COVID-19): A systematic review and meta-analysis of 148 studies from 9 countries

Clinical manifestations of children with COVID-19: A systematic review

Thoracic imaging tests for the diagnosis of COVID-19

Lung Ultrasonography for the Diagnosis of SARS-CoV-2 Pneumonia in the Emergency Department