COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

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Diagnosis Kwee RM, Adams HJA, Kwee TC Diagnostic Performance of CO-RADS and the RSNA Classification System in Evaluating COVID-19 at Chest CT: A Meta-Analysis. Radiol Cardiothorac Imaging. 2021 Jan 14;3(1):e200510. doi: 10.1148/ryct.2021200510. eCollection 2021 Feb.

Purpose: To determine the diagnostic performance of the COVID-19 Reporting and Data System (CO-RADS) and the Radiological Society of North America (RSNA) categorizations in patients with clinically suspected coronavirus disease 2019 (COVID-19) infection.

Materials and Methods: In this meta-analysis, studies from 2020, up to August 24, 2020 were assessed for inclusion criteria of studies that used CO-RADS or the RSNA categories for scoring chest CT in patients with suspected COVID-19. A total of 186 studies were identified. After review of abstracts and text, a total of nine studies were included in this study. Patient information (n¸ age, sex), CO-RADS and RSNA scoring categories, and other study characteristics were extracted. Study quality was assessed with the QUADAS-2 tool. Meta-analysis was performed with a random effects model.

Results: Nine studies (3283 patients) were included. Overall study quality was good, except for risk of non-performance of repeated reverse transcriptase polymerase chain reaction (RT-PCR) after negative initial RT-PCR and persistent clinical suspicion in four studies. Pooled COVID-19 frequencies in CO-RADS categories were: 1, 8.8%; 2, 11.1%; 3, 24.6%; 4, 61.9%; and 5, 89.6%. Pooled COVID-19 frequencies in RSNA classification categories were: negative 14.4%; atypical, 5.7%; indeterminate, 44.9%; and typical, 92.5%. Pooled pairs of sensitivity and specificity using CO-RADS thresholds were the following: at least 3, 92.5% (95% CI: 87.1, 95.7) and 69.2% (95%: CI: 60.8, 76.4); at least 4, 85.8% (95% CI: 78.7, 90.9) and 84.6% (95% CI: 79.5, 88.5); and 5, 70.4% (95% CI: 60.2, 78.9) and 93.1% (95% CI: 87.7, 96.2). Pooled pairs of sensitivity and specificity using RSNA classification thresholds for indeterminate were 90.2% (95% CI: 87.5, 92.3) and 75.1% (95% CI: 68.9, 80.4) and for typical were 65.2% (95% CI: 37.0, 85.7) and 94.9% (95% CI: 86.4, 98.2).

Conclusion: COVID-19 infection frequency was higher in patients categorized with higher CORADS and RSNA classification categories.

Discipline / Specialty Area Score
Hospital Doctor/Hospitalists
Internal Medicine
Infectious Disease
Pediatric Hospital Medicine
Comments from MORE raters

Hospital Doctor/Hospitalists rater

This is a very relevant study. CT studies can be helpful when clinical suspicion is high but the available PCR or Antigen tests are inconclusive and negative requiring multiple tests during the course of illness, as they do have limitations. However, all patients who has tested positive should not be getting CTs and have unwarranted radiation exposure. This should be highlighted in management algorithms.

Infectious Disease rater

These results might be helpful in determining pre-test probability of Covid-19, in patients with clinical suspicion of Covid-19 and negative testing (RADT or PCR). Thus one could calculate the post-(negative)-test probability of Covid-19 and manage the patient accordingly.

Respirology/Pulmonology rater

Meta-analysis finds that the very similar CO-RADS and RSNA classification systems for CT diagnosis of Covid-19 perform similarly. Higher scores correlate well with likelihood of Covid-19. Therefore, chest CT can be a useful adjunct to make a Covid-19 diagnosis if PCR is negative, or unavailable. It should be used selectively due to cost.