Pos1381 Natural Course of Degenerative Changes of the Spine on Radiographs and Mri in Axial Spondyloarthritis Followed 10 Years in the Desir Cohort

Background: Radiographs and magnetic resonance imaging (MRI) are the two imaging techniques usually used to assess structural lesions in axial spondyloarthritis (axSpA). The prevalence of degenerative changes in the spine has been reported high in patients with axSpA 1 but their natural course is not well-known. Objectives: To investigate the degenerative lesions and their changes over 10 years (10Y) in patients with axSpA. Methods: Whole spine MRI and cervical and lumbar spine radiographs at baseline, 5Y and 10Y of patients diagnosed with axSpA in the DESIR cohort were assessed for degenerative lesions by three central readers blinded to timepoint and to clinical or any other imaging information1. Only completers, defined as those with baseline and 10Y data, were included in this analysis. Each degenerative lesion (Tables 1 and 2) was based on agreement between ≥2 out of 3 central readers for binary results and an average of 3 central readers for continuous results. Patient characteristics and degenerative lesions at the patient level (at least one lesion in at least one vertebral level per patient) were reported using frequency for categorical data and mean and standard deviation (SD) for continuous data. We determined the proportion of patients with positive change (% with at least one specific lesion in at least one vertebral level at 10Y in a patient who had no such lesion at baseline) and negative change (% with no specific lesion at 10Y in a patient who had at least one such lesion in at least one vertebral level at baseline) over a 10Y period for each MRI and radiographic lesion. The net percentage change (net progression) between 0 and 10Y was calculated as the number of patients with a positive change minus the number of patients with a negative change divided by the total number of patients included in the analysis. Finally, we compared the number of degenerative lesions at baseline and at 10Y on both imaging modalities using paired Student's t-tests. Results: Analysis of degenerative lesions on radiographs was available for 290 patients (34. 2 SD 8. 6 years; 48% men) and on MRI for 283 patients (34. 4 8. 5 years; 47% men). The most frequent degenerative lesions on radiographs were loss of disc height (45% at baseline, 65% at 10Y, net progression: +20%), followed by osteophytes (21% at baseline, 44% at 10Y, net progression: +22%) and facet joint osteoarthritis (11% at baseline, 24% at 10Y, net progression: +13%) (Table 1). An average of 1. 6 (2. 5) degenerative lesions per patient were observed on radiographs at baseline; this number increased to 3. 4 (3. 9) at 10Y (p-value -4). In total, 47% of patients had no degenerative lesion at baseline and 29% at 10Y. The most frequent degenerative lesions on MRI were disc degeneration (Pfirrmann classification > 2: 86% at baseline, 95% at 10Y, net progression: +9%), followed by high-intensity zone (50% at baseline, 59% at 10Y, net progression: +8%), Schmorl's node without edema (47% at baseline, 50% at 10Y, net progression: +3%) and disc protrusion (45% at baseline, 52% at 10Y, net progression: +7%) (Table 2). An average of 7. 4 (5. 4) degenerative lesions per patient were observed on MRI at baseline; this number increased to 11. 1 (7. 1) at 10Y (p-value -4). Only 6% of patients had no degenerative lesion at baseline and 3% at 10Y follow-up. Degenerative lesions were more frequent in the lumbar spine on radiographs (Table 1) and were evenly distributed on MRI (Table 2). Conclusion: The prevalence of spinal degenerative changes is high in an inception cohort of axSpA with the total number of degenerative lesions increasing over 10Y in all parts of the spine on both radiographs and MRI. Therefore, in axSpA, degenerative lesions are important to be borne in mind when interpreting imaging, particularly after several years of follow-up. REFERENCES: 1 de Bruin F et al. RMD Open. 2018;4 (1): e000657. Acknowledgements: NIL. Disclosure of Interests: Laura Pina Vegas: None declared, Miranda van Lunteren: None declared, Damien Loeuille: None declared, Caroline Morizot: None declared, Esther Newsum: None declared, Sofia Ramiro: research grants and/or consulting fees from AbbVie, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Pfizer, UCB, Sanofi, F. A. van Gaalen: grant and/or consulting fees from, Abbvie, ASAS, BMS, Galapagos, Janssen, Lilly, Novartis, Pfizer, UCB, Alain Saraux: None declared, PASCAL CLAUDEPIERRE: consulting fees from AbbVie, Amgen, Biogen, Celltrion, Galapagos, Janssen, Lilly, MSD, Novartis, Pfizer and UCB (less than US10 000 each) ; investigator for Abbvie, Janssen, Lilly, MSD, Novartis and Pfizer, Antoine Feydy: None declared, Désirée van der Heijde: consulting fees AbbVie, BMS, Galapagos, Glaxo-Smith-Kline, Janssen, Lilly, Novartis, Pfizer, Takeda UCB Pharma; director of Imaging Rheumatology bv, Monique Reijnierse: ASAS consultant; ISS research grant.