Interobserver agreement
| Variable | Interobserver Agreement CTFa | Interobserver Agreement Nordica |
|---|---|---|
| Intravertebral herniation | 0.530 (0.415; 0.657) | 0.481 (0.236; 0.673) |
| Disk contour at L1-L2, L2-L3, and L3-L4b | 0.476 (0.398; 0.573) | 0.473 (0.286; 0.560) |
| Disk contour at L4-L5 and L5-S1 | ||
| Considering bulging as abnormalb | 0.562 (0.426; 0.788) | 0.456 (0.179; 0.650) |
| Considering bulging as normalc | 0.407 (0.261; 0.597) | 0.277 (0.000; 0.571) |
a Mean (5th percentile, 95th percentile) of κ values. Agreement is classified as almost perfect (κ value > 0.81), substantial (0.61–0.80), moderate (0.41–0.60), fair (0.21–0.40), slight (0.00–0.20), or poor (<0.00).18
b Agreement in classifying images in the 2 following categories: normal vs bulging + focal protrusion + broad-based protrusion + extrusion, according to the CTF nomenclature; or normal vs symmetric bulging + protrusion (focal or broad-based) + hernia (extrusion or sequestration), according to the Nordic nomenclature.
c Agreement in classifying images in the 2 following categories: normal + bulging vs focal protrusion + broad-based protrusion + extrusion, according to the CTF nomenclature; or normal + symmetric bulging vs protrusion (focal or broad-based) + hernia (extrusion or sequestration), according to the Nordic nomenclature.