Table 1.

Inter-reader agreement of breast density according to BI-RADS classifications. Results of the experienced reader are presented in the columns, results of the inexperienced reader are presented in the rows

		Experienced reader
		BI-RADS 1	BI-RADS 2	BI-RADS 3	BI-RADS 4	Total
Inexperienced reader	BI-RADS 1	66 (33.0%)	2 (1.0%)	2 (1.0%)	0 (0.0%)	70 (35.0%)
	BI-RADS 2	19 (9.5%)	36 (18.0%)	1 (0.5%)	0 (0.0%)	56 (28.0%)
	BI-RADS 3	5 (2.5%)	38 (19.0%)	10 (5.0%)	0 (0.0%)	53 (26.5%)
	BI-RADS 4	1 (0.5%)	3 (1.5%)	14 (7.0%)	3 (1.5%)	21 (10.5%)
	Total	91 (45.5%)	79 (39.5%)	27 (13.5%)	3 (1.5%)	200 (100.0%)

The overall weighted kappa was 0.521, a moderate value (95% confidence interval 0.446–0.597)