Table 1 Pathology variables and assessment criteria.

Pathology type	Assessment criteria (individual)¹
Disc degeneration	Condensed Pfirrmann grading (0 = none (0); 1 = slight (1); 2 = moderate (2) to severe (3))
Disc bulge	Present or absent at any level (0 = absent; 1 = present)
Disc herniation	Herniation grading based on any associated NR compromise (grade 0 = no herniation/herniation with no NR compromise (0) or NR contact only (1); grade 1 = displaced NR (2) or compressed NR (3)); herniation location based on apex location: right-sided, central, or left-sided
High intensity zone (HIZ)	Number of levels with HIZ present (0 = none; 1 = one level; 2 = two or more levels)
Modic marrow changes	Modic 1 and 2 changes (upper or lower) assessed separately; graded by maximum height of marrow change (0 = none (0) to < 25% (1); 1 = ≥ 25% (2) to ≥ 50% (3))
Endplate defects	Present or absent at any level (either endplate) (0 = absent; 1 = present)
Vertebral osteophytes	Number of levels with osteophyte(s) present (0 = none; 1 = one level; 2 = two or more levels)
Facet arthrosis (L3/4–L5/S1 only)	Number of levels with grade 1 arthrosis present² (0 = none; 1 = one level; 2 = two or more levels)

Pathology type	Assessment criteria (combined)³
Disc degeneration	Worst condensed Pfirrmann grading (0–3) at any level (0 = 0–1 grading; 1 = 2–3 grading)
Disc bulge	Present or absent at any level (0 = absent; 1 = present)
Disc herniation	Worst sub-grading (0–3) at any level or location (0 = 0–1 sub-grading; 1 = 2–3 sub-grading)
High intensity zone	Present or absent at any level (0 = absent; 1 = present)
Modic marrow changes	Worst Modic 1 or 2 sub-grading (0–3) at any level (0 = 0–1 sub-grading; 1 = 2–3 sub-grading)
Endplate defects	Present or absent at any level (0 = absent; 1 = present)
Vertebral osteophytes	Present or absent at any level (0 = absent; 1 = present)
Facet arthrosis	Worst arthrosis grading (0–1) at any level (0 = 0–1 finding; 1 = 2 + findings)

¹Each pathology assessed from L2/3 through L5/S1 unless otherwise indicated. ²Grading based on number of different degenerative findings (out of 8) present (grade 1 = two or more findings). ³Each pathology scaled at 0 or 1 to standardize analysis of any combinations. NR, nerve root.

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