Article
Identification of predictors of structural damage progression in the sacroiliac joints in patients with early axial Spondyloarthritis on a long-term anti-TNF treatment
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Published: | February 5, 2019 |
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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.
Objective: 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: Patients with early axSpA who were treated with etanercept for up to 6 years in the ESTHER trial were selected based on the availability of X-rays of SIJ. Two blinded readers scored the X-rays according to the grading system of the modified New York criteria (range 0-4 per SIJ). A sacroiliitis sum score (total range 0-8) was calculated as a mean of scores of both readers. Active and chronic inflammatory changes on magnetic resonance imaging (MRI) of SIJ performed at baseline, year 2 and year 4 were assessed according to the Berlin MRI scoring system.
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 [Tab. 1]).
Conclusion: Long-term anti-TNF therapy seems to decelerate progression of structural damage in the SIJ. Elevated CRP and presence of osteitis on MRI were independently associated with radiographic sacroiliitis progression.