LAUSR

STUDY DESIGN Cross-sectional retrospective observational study. OBJECTIVE To evaluate the reliability and clinical utility of the Modic changes (MC) grading score. METHOD Patients from the Danish national spine registry, DaneSpine, scheduled for lumbar discectomy were identified. MRI of patients with MC were graded based on vertical height involvement: Grade A (<25%), Grade B (25%-50%), and Grade C (>50%). All MRIs were reviewed by 2 physicians to evaluate the reliability of the MC grade. RESULTS Of 213 patients included, 142 patients had MC, 71 with MC-1 and 71 with MC-2; 34% were Grade A, 45% were Grade B, and 21% were Grade C. MC grade demonstrated substantial intra-rater (κ = .68) and inter-rater (κ = .61) reliability. A significantly higher proportion (n = 40, 57%) of patients with MC-1 had a severe MC grade compared to patients with MC-2 (n = 30, 43%, P < .001). Severe MC grade was associated with the presence of severe lumbar disc degeneration (DD) (Pfirrmann grade = V, P = .024), worse preoperative ODI (52.49 vs 44.17, P = .021) and EQ-5D scores (.26 vs .46, P = .053). MC alone including type was not associated with a significant difference in patient-reported outcomes (P > .05). CONCLUSION The MC grade score was demonstrated to have substantial intra- and inter-observer reliability. Severe MC grade was associated with both severe DD and MC type, being more prevalent in patients with MC-1. The MC grade was also significantly associated with worse disability and reduced health-related quality of life. Results from the study suggest that MC grade is more clinically important than MC type.