Ten-year follow-up of degenerative spinal lesions on radiographs and MRI in axial spondyloarthritis: results of the DESIR (DEvenir des spondylarthropathies indifférenciées récentes) cohort.

Objectives: To investigate the occurrence of spinal degenerative lesions (DL)s in axial spondyloarthritis (axSpA) inception cohort in radiographs and MRI over 10 years (10Y), to assess their changes over time and factors associated with them.

Methods: Whole spine MRI and cervical and lumbar spine radiographs at baseline/5Y/10Y of patients with axSpA from the DESIR cohort were assessed for DLs by three readers. For descriptive analyses, DLs were defined by agreement between ≥ 2/3 readers or using the average of their assessments, at the patient level (≥ 1 lesion/patient). To assess the progression of DLs over time, we used multilevel generalised estimating equation models considering individual reader data.

Results: Imaging was available for 330 patients (mean age 34 [9] years, 47% male). At baseline, 53% of patients had ≥ 1 DL on radiographs and 94% on MRI; 71% and 97% had DL at 10Y, respectively. The most frequent lesion on radiographs was disc height loss (baseline: 45% of patients, 10Y: 65%) and MRI disc degeneration (86%, 95%). Progression over time on radiographs was detected for osteophytes (change/Y: 2.34%, 95% CI: 1.92-2.75), disc height loss (1.37%, 0.95-1.80) and facet joint osteoarthritis (1.30%, 0.90-1.69) and on MRI for disc bulging/herniation (1.19%, 0.74-1.64), Modic type I (1.01%, 0.69-1.33) and II (0.94%, 0.66-1.22) lesions. We also observed a significant increase per year in the total number of DLs on radiographs (β: 1.81, 1.48-2.14) and MRI (β: 4.17, 3.49-4.84). Associated factors in both modalities were increasing BMI and bDMARDs exposure.

Conclusion: In axSpA spinal DLs, though common, progress very slowly over 10Y. Faster progression is observed with increasing BMI and bDMARDs exposure (severe axSpA).

Key Points: Question The long-term evolution of spinal DLs in axSpA on radiographs and MRI, and the associated factors, is currently poorly understood. Findings Spinal DLs, although common, progress slowly over 10Y, but in patients with a higher BMI or exposed to bDMARDs, the progression is faster. Clinical relevance Understanding the progression of spinal DLs in axSpA helps to refine the interpretation of long-term imaging, limit diagnostic errors and optimise management strategies, particularly in patients with the highest risk of progression of these lesions.