OP0025 Identification of predictors of structural damage progression in the sacroiliac joints in patients with early axial spondyloarthritis on a long-term anti-tnf treatment

Background Several observational studies showed a low, but still detectable progression of structural damage in the sacroiliac joints (SIJ) in patients with axial spondyloarthritis (axSpA) over 2 to 5 years. Few predictors of progressions, such as elevated C-reactive protein (CRP) and active inflammation on magnetic resonance imaging (MRI), have been identified, mostly in patients not treated with TNF inhibitors. To date, it is not clear whether these predictors also work in patients treated with anti-TNF agents and whether anti-TNF therapy is able to retard such a progression. Objectives To evaluate the radiographic progression in the sacroiliac joints (SIJ) and to identify predictors of such a progression during long-term (up to six years) treatment with tumour necrosis factor (TNF) blocker etanercept in patients with early axSpA. Methods In the ESTHER trial 1 a total of 76 patients with early (up to 5 years symptom duration) and active axSpA were randomised to be treated with either etanercept or sulfasalazine for one year. Between year 1 and year 6, all patients who continued in the study were treated with etanercept. X-rays of SIJ were collected at baseline and every 2 years thereafter. Two trained readers, who were blinded for all clinical data, scored independently the SIJ x-rays in a concealed and randomly selected order, according to the grading system of the modified New York (mNY) criteria (grade 0 to 4). Patients with bilateral sacroiliitis of grade ≥2 or unilateral of grade ≥3 were classified as radiographic axSpA (r-axSpA), and as non-radiographic axSpA (nr-axSpA) otherwise. The sacroiliitis sum score (0–8) was calculated as a sum of means of both readers for the left and right SIJ. Active and chronic inflammatory changes on MRI of SIJ were assessed at baseline, year 2 and year 4 according to the Berlin MRI scoring system. A longitudinal mixed model analysis was performed to identify predictors of the radiographic sacroiliitis progression. Results Totally, 55 patients with axSpA contributing with 159 SIJ radiographs were included in the analysis. At baseline, 19 patients were classified as r-axSpA and 36 as nr-axSpA based on the independent SIJ reading. Radiographic progression from nr- to r-axSpA was observed in 5 (18%) patients between baseline and year 2. Progression decelerated to 4.1% between year 2 and 4, and no further progression was observed up to year 6. The mean ±SD change of sacroiliitis sum score was 0.13±0.73,–0.26±0.76 and −0.09±0.67, in the time intervals baseline-year 2, year 2 year 4, and year 4 year 6, respectively. In the longitudinal mixed model analysis, elevated CRP (model 2) and osteitis on MRI (model 1) were independently and significantly associated with a higher sacroiliitis sum score (table 1). Conclusions Long-term therapy with a TNF blocker seems to decelerate progression of structural damage in the SIJ. Elevated CRP and presence of osteitis in MRI were independently associated with SIJ radiographic progression. Reference [1] Song IH, et al. Ann Rheum Dis2011;70(4):590–596. Acknowledgements the ESTHER study was supported by an unrestricted research grant from Pfizer. Disclosure of Interest V. Rios Rodriguez Consultant for: Abbvie, Novartis, K.-G. Hermann Speakers bureau: Abbvie, MSD, Pfizer, UCB, H. Haibel: None declared, C. Althoff: None declared, O. Behmer Employee of: Pfizer, J. Sieper Grant/research support from: Abbvie, MSD, Pfizer, Consultant for: Abbvie, MSD, Pfizer, UCB, D. Poddubnyy Grant/research support from: Abbvie, MSD, Novartis, Consultant for: Abbvie, BMS, MSD, Novartis, Pfizer, UCB, Speakers bureau: Abbvie, BMS, Janssen, MSD, Novartis, Pfizer, Roche, UCB