Table 3.

CO-RADS inter-observer agreement and performance

CO-RADS assessment score	Fleiss’ K overall for all readers	Fleiss’ K for chest radiologists (R1 and R2)	Fleiss’ K for general radiologist (R3 and R4)	Fleiss’ K for radiologists in training (R5 and R6)
CO-RADS 1	0.71 (0.71, 0.72)	0.81 (0.80, 0.81)	0.80 (0.80, 0.81)	0.76 (0.76, 0.77)
CO-RADS 2	0.46 (0.46, 0.46)	0.70 (0.70, 0.71)	0.26 (0.25, 0.26)	0.54 (0.54, 0.55)
CO-RADS 3	0.17 (0.17, 0.17)	0.31 (0.31, 0.32)	0.10 (0.10, 0.11)	0.37 (0.37, 0.38)
CO-RADS 4	0.07 (0.07, 0.07)	0.14 (0.14, 0.15)	0.33 (0.33, 0.34)	0.18 (0.17, 0.18)
CO-RADS 5	0.67 (0.67, 0.67)	0.79 (0.78, 0.79)	0.73 (0.72, 0.73)	0. 61 (0.61, 0.62)
Overall	0.54 (0.54, 0.54)	0.68 (0.67, 0.68)	0.61 (0.61, 0.61)	0.56 (0.56, 0.56)

The inter-observer agreement for various CO-RADS category, overall among all readers and within the groups. Data in parenthesis are 95% confidence interval