BACKGROUND: Computed tomography (CT) is thought to play a key role in COVID-19 diagnostic work-up. The possibility to compare data across different settings depends on the systematic and reproducible manner the scans are analyzed and reported. The COVID-19 Reporting and Data System (CO-RADS) and the corresponding CT severity score (CTSS) introduced by the Radiological Society of the Netherlands (NVvR) attempt to do so. However, this system has not been externally validated. RESEARCH QUESTION: We aimed to prospectively validate the CO-RADS as a COVID-19 diagnostic tool at the emergency department (ED), and evaluate if the CTSS is associated with prognosis. STUDY DESIGN METHODS: We conducted a prospective, observational study in two tertiary centers in The Netherlands, between March 19 and May 28, 2020. We consecutively included 741 adult patients at the ED with suspected COVID-19, who received a chest CT and SARS-CoV-2 PCR (PCR). Diagnostic accuracy measures were calculated for CO-RADS using PCR as reference. Logistic regression was performed for CTSS in relation to hospital admission, ICU admission and 30-day mortality. RESULTS: 741 patients were included. We found an AUC of 0.91 (CI 0.89-0.94) for CO-RADS using PCR as reference. The optimal CO-RADS cut-off was 4, with a sensitivity of 89.4% (CI 84.7-93.0) and specificity of 87.2% (CI 83.9-89.9). We found a significant association between CTSS and hospital admission, ICU admission, and 30-day mortality; adjusted odds ratios per point increase in CTSS were 1.19 (CI 1.09-1.28), 1.23 (1.15-1.32), 1.14 (1.07-1.22), respectively. Intra-class correlation coefficients for CO-RADS and CTSS were 0.94 (0.91-0.96) and 0.82 (CI 0.70-0.90). INTERPRETATION: Our findings support the use of CO-RADS and CTSS in triage, diagnosis and management decisions for patients presenting with possible COVID-19 at the ED.
Chest CT in COVID-19 at the ED: Validation of the COVID-19 Reporting and Data System (CO-RADS) and CT severity score