Table 6. Interobserver agreement regarding characteristics of the disc herniation.

	A vs B(n = 314)		A vs C(n = 313)		B vs C(n = 301)		All observers(n = 296)
	%agreement	kappa	%agreement	kappa	%agreement	kappa	%agreement	kappa
Side of disc herniation|--	98.1	0.96	98.4	0.97	98.0	0.96	97.6	0.97
Location axial view ¶	94.2	0.88	95.5	0.90	96.7	0.93	95.6	0.92
Location sagittal view ∥	73.2	0.55	76.9	0.63	71.3	0.53	61.4	0.56
Size disc herniation in relation to spinal canal(4 categories) §	56.6	0.46	60.6	0.46	64.3	0.50	42.7	0.36
Size disc herniation in relation to spinal canal(2 categories) ‡	82.1	0.55	76.3	0.35	86.3	0.47	71.5	0.44
Protrusion versus extrusion	77.4	0.48	75.0	0.50	73.7	0.44	63.2	0.46

The number between brackets on the first row is the number of patients of which the observers suggested the presence of a disc herniation (on the same disc level). A en B represent the two neuroradiologists, while C represents the neurosurgeon.

^|--Categories were: 1) Right 2) Left 3) Right and left.

^¶Categories were: 1) Central zone 2) Sub-articular zone 3) Foraminal zone 4) Extra-foraminal zone.

^∥Categories were: 1) Disc level 2) Folded upwards 3) Folded downwards.

^§Categories were: 1) Large stenosing: size >75% of the spinal canal 2) Large: size 50–75% of the spinal canal 3) Average: size 25–50% of the spinal canal and 4) Small: size <25% of the spinal canal.

^‡The categories “large stenosing” and “large” were combined to one category and the categories “average” and “small” were also combined to one category.