COVID-19 pneumonia: Diagnostic and prognostic role of CT based on a retrospective analysis of 214 consecutive patients from Paris, France

Guillo, Enora; Bedmar Gomez, Ines; Dangeard, Severine; Bennani, Souhail; Saab, Ines; Tordjman, Mickael; Jilet, Lea; Chassagnon, Guillaume; Revel, Marie-Pierre

OBJECTIVES: To evaluate the diagnostic and prognostic performance of CT in patients referred for COVID19 suspicion to a French university hospital, depending on symptoms and date of onset. METHODS: From March 1(st) to March 28(th), 214 patients having both chest CT scan and reverse transcriptase polymerase chain reaction (RT- PCT) within 24 hours were retrospectively evaluated. Sensitivity, specificity, negative and positive predictive values of first and expert readings were calculated together with inter reader agreement, with results of RT-PCR as standard of reference and according to symptoms and onset date. Patient characteristics and disease extent on CT were correlated to short-term outcome (death or intubation at 3 weeks follow-up). RESULTS: Of the 214 patients (119 men, mean age 59 ± 19 years), 129 had at least one positive RT-PCR result. Sensitivity, specificity, negative and positive predictive values were 79% (95% CI: 71- 86%), 84%(74- 91%), 72%(63-81%) and 88% (81-93%) for initial CT reading and 81%(74- 88%), 91% (82-96%), 76% (67-84%) and 93% (87-97%), for expert reading, with strong inter-reader agreement (kappa index: 0.89). Considering the 123 patients with symptoms for more than 5 days, the corresponding figures were 90%, 78%, 80% and 89% for initial reading and 93%, 88%, 86% and 94% for the expert. Disease extent exceeded 25% for 68% and 26% of severe and non-severe patients, respectively (p < 0.001). CONCLUSION: CT sensitivity increased after 5 days of symptoms. A disease extent > 25% was associated with poorer outcome.