Emergency department CT examinations demonstrate no evidence of early viral circulation at the start of the COVID-19 pandemic—a multicentre epidemiological study

Insights into Imaging

Table 5 Distribution of the target reports and highly suspicious chest CT scans (with corresponding predicted probabilities for positive RT-PCR) over the study period

	Target reports (n = 146)	SFR ≥ IV-IV-IV (n = 37)	SFR = V-V-V (n = 22)
No. of patients per month
September 2019	17	3	2
October 2019	13	2	0
November 2019	11	2	0
December 2019	17	0	0
January 2020	24	2	2
February 2020	21	6	4
March 2020	43	22	14
Average predicted probabilities
CART model	0.739 ± 0.141	0.831 ± 0.057	0.853 ± 0.038
Step-LR model	0.622 ± 0.243	0.852 ± 0.118	0.926 ± 0.045

Data are number of patients (with percentage in parentheses), except for probabilities for positive RT-PCR according to the predictive models, which are mean probability ± standard deviation
Numbers in bold correspond to the patients who were included in the clinical and biological complementary investigations
Abbreviations: CART classification and regression trees, GGO ground glass opacities, SFR French ‘Société Française de Radiologie’, Step-LR stepwise logistic regression