Table 1. Concordance of selected diagnoses of 355 HNC cases included in the pathology review by slide and pathologist.

Histological characteristics	First reading (Pathologist 1)				Review (Pathologist 2)				Inter-pathologist concordance*
	First slide		Last slide		First slide		Last slide		% Concordance	Kappa (p-value)	Pabak	McNemar test p-value
	n	%	n	%	n	%	n	%
Quality of tissue									86.1	0.34 (<0.001)	0.72	0.86
Satisfactory	308	86.8	304	85.6	308	86.8	307	86.5
Unsatisfactory	25	7.0	34	9.6	25	7.0	30	8.5
Sub-optimal quality	15	4.2	10	2.8	20	5.6	17	4.8
% Intra-pathologist concordance	96.8				96.6
Kappa (p-value)	0.85 (<0.001)				0.86 (<0.001)
McNemar test p-value	0.03				0.31
Percentage of invasive carcinoma									36.5	0.11 (<0.001)	NA	0.11
0%	12	3.4	15	4.2	11	3.1	17	4.8
<10%	32	9.0	27	7.6	31	8.3	30	8.5
10–50%	64	18.0	61	17.2	64	18.0	61	17.2
50–90%	118	33.2	115	32.4	157	44.2	152	42.8
> 90%	97	27.3	95	26.8	67	18.9	57	16.1
% Intra-pathologist concordance	91.9				93.3
Kappa (p-value)	0.89 (<0.001)				0.90 (<0.001)
McNemar test p-value	0.53				0.07
Percentage of tumoral necrosis									60.7	0.25 (<0.001)	0.21	0.18
0%	189	53.2	185	52.1	216	60.9	208	58.6
<10%	86	24.2	79	22.3	74	20.9	68	19.2
10–50%	27	7.6	29	8.2	29	8.2	30	8.5
>50%	7	2.0	8	2.3	5	1.4	5	1.4
% Intra-pathologist concordance	96.6				97.4
Kappa (p-value)	0.94 (<0.001)				0.95 (<0.001)
McNemar test p-value	0.27				0.34
Normal epithelium									73.6	0.44 (<0.001)	0.47	0.06
Absent	138	38.9	137	38.6	123	34.7	120	33.8
Present	207	58.3	202	56.9	228	64.2	224	63.1
% Intra-pathologist concordance	96.7				96.2
Kappa (p-value)	0.93 (<0.001)				0.92 (<0.001)
McNemar test p-value	0.37				0.78

NA: Not applicable. For some variables the cases do not sum 355 because of missing values or slides not evaluated.

*Calculated by comparing the first slides’ diagnoses