Table 2.

Concordance rates of the refined HER2 score

Interobserver concordance of the refined HER2 score between the two observers
Second observer score	First observer score				Kappa value
	0	1	2	Total
0	128 (93.4%)	9 (6.6)	0	137	0.85
1	8 (5.7)	122 (87.1%)	10 (7%)	140
2	0	9 (10.5%)	77 (89.5%)	86
Total	136	140	87	363
Intra‐observer agreement of HER2 score using the refined criteria
Refined HER2 score (second)*	Refined HER2 score (first)				0.83
	0	1	2	Total
0	124 (92%)	11 (8%)	0	135
1	12 (8.3%)	119 (82.6%)	13 (9%)	144
2	0	10 (12%)	74 (88%)	84
Total	136	140	87	363

^*Carried out by the first observer after 3 months washout period from the 1st score. HER2, human epidermal growth factor receptor 2.