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Table 5 Inter-rater agreement for CO-RADS classification

From: Comparison of the RSNA chest CT classification system and CO-RADS system in reporting COVID-19 pneumonia in symptomatic and asymptomatic patients

   CO-RADS by rater 1 CO-RADS by rater 2
   CO-RADS 1 CO-RADS 2 CO-RADS 3 CO-RADS 4 CO-RADS 5 CO-RADS 1 CO-RADS 2 CO-RADS 3 CO-RADS 4 CO-RADS 5
CO-RADS by rater 2 CO-RADS 1 64 6 2 2 1      
CO-RADS 2 4 22 3 0 0      
CO-RADS 3 6 10 8 2 2      
CO-RADS 4 4 5 16 6 1      
CO-RADS 5 2 6 13 14 52      
CO-RADS by rater 3 CO-RADS 1 55 8 7 0 1 55 3 10 1 2
CO-RADS 2 10 27 3 3 0 6 21 7 6 3
CO-RADS 3 5 6 6 3 0 5 3 4 4 4
CO-RADS 4 8 4 8 7 3 7 2 3 12 6
CO-RADS 5 2 4 18 11 52 2 0 4 9 72
Inter-rater agreement  
Model, type Two-way random, single measurement
Definition Absolute agreement
Number of subjects (n), number of raters (k) 251, 3
Intra class correlation coefficient (ICC) 0.75*
95% CI 0.70–0.80
  1. Data in cross-tables are counts. 95% CI = 95% confidence interval
  2. *An ICC of 0.75 denotes good inter-rater reliability for CO-RADS classification