COVID-19 Pneumonia: Inter-Observer Agreement and Diagnostic Accuracy of Chest CT in Patients with Intermediate Clinical Probability
Abstract Objectives To assess inter-reader agreements and diagnostic accuracy of chest CT to identify COVID-19 pneumonia in patients with intermediate clinical probability during an acute disease outbreak.Methods:From March 20 to April 8, consecutive patients with intermediate clinical probability of COVID-19 pneumonia underwent a chest CT scan. Two independent chest radiologists blinded to clinical information and RT-PCR results retrospectively reviewed and classified images on a 1-5 confidence level scale for COVID-19 pneumonia. Agreements between radiologists were assessed with kappa statistics. Diagnostic accuracy of chest CT compared to RT-PCR assay and patient outcomes was measured using receiver operating characteristics (ROC). Positive predictive value (PPV) and negative predictive value (NPV) for COVID-19 pneumonia were calculated.Results: 319 patients with a mean age of 62.3 yo were included. Inter-observer agreement for highly probable (kappa: 0.83 [p < .001]) and highly probable or probable (kappa: 0.82 [p < .001]) diagnosis of COVID-19 pneumonia was very good. RT-PCR tests performed in 307 patients were positive in 173 and negative in 134. Sixteen patients with negative RT-PCR tests and probable or highly probable CT patterns according to both radiologists were reclassified COVID-19 positive after clinical discussion. The areas under the curve (AUC) were 0.94 and 0.92 respectively. With a disease prevalence of 61.6%, PPV were 96.6 % and 94.4%, and NPV 84.3% and 78.2%.Conclusion :During acute COVID-19 outbreak, chest CT scan may be used for triage of patients with intermediate clinical probability with very good inter-observer agreements and diagnostic accuracy.