COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

Diagnosis Bellini D, Panvini N, Rengo M, et al. Diagnostic accuracy and interobserver variability of CO-RADS in patients with suspected coronavirus disease-2019: a multireader validation study. Eur Radiol. 2020 Sep 23. pii: 10.1007/s00330-020-07273-y. doi: 10.1007/s00330-020-07273-y.

OBJECTIVE: To conduct a multireader validation study to evaluate the interobserver variability and the diagnostic accuracy for the lung involvement by COVID-19 of COVID-19 Reporting and Data System (CO-RADS) score.

METHODS: This retrospective study included consecutive symptomatic patients who underwent chest CT and reverse transcriptase-polymerase chain reaction (RT-PCR) from March 2020 to May 2020 for suspected COVID-19. Twelve readers with different levels of expertise independently scored each CT using the CO-RADS scheme for detecting pulmonary involvement by COVID-19. Receiver operating characteristic (ROC) curves were computed to investigate diagnostic yield. Fleiss' kappa statistics was used to evaluate interreader agreement.

RESULTS: A total of 572 patients (mean age, 63 ± 20 [standard deviation]; 329 men; 142 patients with COVID-19 and 430 patients without COVID-19) were evaluated. There was a moderate agreement for CO-RADS rating among all readers (Fleiss' K = 0.43 [95% CI 0.42-0.44]) with a substantial agreement for CO-RADS 1 category (Fleiss' K = 0.61 [95% CI 0.60-0.62]) and moderate agreement for CO-RADS 5 category (Fleiss' K = 0.60 [95% CI 0.58-0.61]). ROC analysis showed the CO-RADS score = 4 as the optimal threshold, with a cumulative area under the curve of 0.72 (95% CI 66-78%), sensitivity 61% (95% CI 52-69%), and specificity 81% (95% CI 77-84%).

CONCLUSION: CO-RADS showed high diagnostic accuracy and moderate interrater agreement across readers with different levels of expertise. Specificity is higher than previously thought and that could lead to reconsider the role of CT in this clinical setting.

KEY POINTS: • COVID-19 Reporting and Data System (CO-RADS) demonstrated a good diagnostic accuracy for lung involvement by COVID-19 with an average AUC of 0.72 (95% CI 67-75%). • When a threshold of = 4 was used, sensitivity and specificity were 61% (95% CI 52-69%) and 81% (95% CI 76-84%), respectively. • There was an overall moderate agreement for CO-RADS rating across readers with different levels of expertise (Fleiss' K = 0.43 [95% CI 0.42-0.44]).

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

Emergency Medicine rater

CT continues to show that it can be a reliable screening tool when rapid PCR is not available. Unfortunately, the long-term financial and radiation-related costs are unknown at this time.

Infectious Disease rater

This study shows that using a rating scheme for chest images produces pretty good agreement among radiologists of varying experience levels. Not sure how useful this information is to other specialties.

Infectious Disease rater

Interesting study of the diagnostic accuracy of CT scan for COVID-19. However, it is worth noting that this study doesn`t (and couldn`t) answer what will be a critical question for the next few months: Can CT reliably distinguish COVID-19 from other respiratory pneumonias, in particular influenza? The discriminatory value will be critical as flu season approaches.

Internal Medicine rater

May be of value to radiologists but seems less useful to those at point-of-care.

Internal Medicine rater

CT is useful but not definitive.