A detailed statistical analysis of the performance of CO-RADS and CT-severity score in the diagnosis of COVID-19 pneumonia compared to RT-PCR test: a prospective cohort study

Background Reports from international studies regarding the role of CT scan and RT-PCR test in the diagnosis of coronavirus disease has been a subject of controversy. The purpose of this study was to statistically compare the performance of CT in reporting chest CT scans of coronavirus disease according to Coronavirus Disease Reporting and Data System (CO-RADS) and CT severity score (CTSS) with the performance of RT-PCR test. Results The analyzed CT scans of 144 participants were consistent with CO-RADS 1 (n = 38), CO-RADS 2 (n = 11), CORADS 3 (n = 35), CO-RADS 4 (n = 23), and CO-RADS 5 (n = 37). CTSS in CO-RADS 1 was (0.9 +/- 4), CO-RADS 2 (4 +/- 2), CORADS 3 (10.2 +/- 2), CO-RADS 4 (14 +/- 6) and CO-RADS 5 (19 +/- 7). There was direct correlation between CO-RADS groups and CTSS (p < 0.001). The mean total CTSS was 10 +/- 9 for the whole study population. Ninety-five CT scans were compatible with CO-RADS 3, 4 or 5 and 49 CT scans were compatible with CO-RADS 1 or 2, with a positive rate of 66% (95% CI 49%, 65%), PPV (55.41%), NPV (45.18%), accuracy (86.8%) and the overall sensitivity (93.18%) and specificity (76.8%) of CT in detecting COVID-19 pneumonia when categorized and analyzed according to CO-RADS and CTSS. Sixty-four patients had positive initial RT-PCR tests and 80 patients had negative initial RT-PCR test, with a positive rate of 44.4% (95% CI 35%, 51%), PPV (41.13%), NPV (59.51%), accuracy (74.3%), sensitivity (64.2%) and specificity (93.9%). The Kappa (.) value of average inter-reader agreement was 88% (95% CI 80%, 96%). Conclusions RT-PCR test showed higher specificity and NPV compared to CT in detecting COVID-19 pneumonia, while CT showed higher sensitivity, PPV, accuracy and positive rate, respectively. CT was superior to RT-PCR test in detecting COVID-19 pneumonia especially at early stages of the disease.