Background/Purpose: Only few studies have investigated long-term radiographic progression in the spine of patients with ankylosing spondylitis (AS). Moreover, no studies have reported changes in MRI lesions of inflammation and structural damage in the sacroiliac joints (SIJs) and spine assessed with annually repeated scans over 5 years. The aim was to investigate radiographic progression and evolution of MRI inflammation and structural lesions during treatment with TNFα inhibitors over 5 years assessed with serial examinations.

Methods: The study included 33 patients with AS followed for 5 years. All patients had participated in the BIOSPA study(1), which included 60 patients initiating treatment with TNFα inhibitor (infliximab, etanercept or adalimumab). Spinal radiographs were obtained 4 times (at week 0, 46, year 3 and 5) and MRIs of the SIJs and the lower spine (Th9-S1) were acquired 7 times (at week 0, 22 and 46 and annually to year 5), respectively. The images were evaluated in known time order without other information available. The SPARCC Sacroiliac and Spine Inflammation Index and Structural Scores (SSS) (2) and the Canada-Denmark (CanDen) scores of inflammation, fat(3), erosions and new bone formation (4,5) were used for the MRI evaluations. The modified Stoke AS Spine Score (mSASSS)(6) were used for the evaluation of the radiographs.

Results: During 5 years of TNFα inhibitor treatment, mSASSS increased significantly at all study visits (p<0.01) (Figure 1), and the structural MRI spine score SASSS increased significantly from year 2 (p<0.05). The mSASSS progression rate was significantly lower from week 46 to year 3 (0.45 units/year) than from week 0 to 46 (1.71 unit/year), whereas there was no difference in the progression rate from week 0 to 46 versus year 3 to 5 (0.66 units/year, p=0.055). MRI inflammation decreased significantly in SIJ (p<0.05) and spine from week 22 (p<0.01, except for year 5), together with a significant decrease of SIJ erosion from week 46 (p<0.05) and throughout the study. Conversely, the SIJ and spinal MRI fat (p<0.05) and SIJ ankylosis scores increased significantly from week 22 (p<0.05). Only minor changes were observed for SIJ backfill and spine erosion score.

Conclusion: Radiographic progression decreased significantly after the first year of treatment with TNFα inhibitor. Spine and SIJ MRI inflammation and structural scores changed significantly short after initiation of treatment, and thereafter the scores remained statistically unchanged except. References: 1. Pedersen et al. Ann Rheum Dis ; 2. Maksymowych et al. J Rheumatol 2014; 3. Pedersen et al. Arthritis Res Ther 2014; 4. Lambert et al. J Rheumatol 2009 5. Østergaard et al. J Rheumatol 2009; 6. Averns HL et al. Br J Rheumatol 1996