Session Type: Poster Session A
Session Time: 8:30AM-10:30AM
Background/Purpose: The aim of this study is to investigate the performance of the modified Stokes Ankylosing Spondylitis Scoring System (mSASSS) in assessing spinal radiographic damage and progression in axial spondyloarthritis (axSpA) using different approaches of radiographs (CR) evaluations.
Methods: Complete sets of cervical and lumbar CRs of patients with axSpA from the German SpA Inception Cohort (GESPIC) at baseline and after 2 years were first blinded to all clinical and demographic characteristics and then scored using the mSASSS by 5 different experienced readers, 2 blinded and 3 unblinded to the timepoint of CR performance. The final mSASSS score was calculated as a mean of 2 (blinded) or 3 (unblinded exercise) readers. Descriptive statistics, cumulative probability plots and shift analyses (agreement of 2/2 readers in the blinded group and 2/3 readers in the unblinded group on the level of single vertebral edges) were performed for each reader group.
Results: A total of 210 patients (mean age 37.3 years, 51% male, 79% HLA-B27 positive) with axSpA (115 radiographic and 95 non-radiographic at baseline) were included. The mean mSASSS score at baseline was 4.3±8.3 vs. 3.4±7.9, while the mean radiographic progression was 0.7±2.3 vs.1.0±1.9 mSASSS units for the blinded vs. the unblinded group, respectively (Figure). On the patient level, progression of ≥2 mSASSS units was found in 30 (14.3%) vs. 37 (17.6%) patients in the blinded vs. the unblinded group, while agreement between both groups was seen in 179 (85.2%) patients, 18 (8.9%) patients for progression and 161 (76.7%) for no progression.
In a more specific analysis of ‘definite’ CR findings (only scores of 2 for syndesmophytes or 3 for ankylosis), the mean mSASSS score at baseline was 3.3±8.0 vs. 2.6±7.2 and the mean radiographic progression was 0.6±2.4 vs. 0.8±2.1 mSASSS units for the blinded vs. the unblinded group, respectively. On the patient level, progression was found in 37 (17.6%) vs. 33 (15.7%) patients in the blinded vs. the unblinded group, while agreement between groups was seen in 188 (89.5%) patients, 24 (11.3%) for progression and in 164 (78.1%) patients for no progression.
In the shift analysis, mSASSS worsening was found in 35 (0.8%) and mSASSS ‘improvement’ in only 4 (0.1%) out of the total of 4.373 vertebral edges analyzed in the blinded group and in 109 (2.2%) and 2 (0.04%), respectively, out of the total of 4.914 vertebral edges analyzed in the unblinded group (Table). The majority of progression was found for the development of ‘definite’ signs of progression (development of syndesmophytes or ankylosis) in both the blinded (25/35, 71.4%) and the unblinded (61/109, 56%) group, while more vertebral edges showing ‘minor’ signs of progression (no syndesmophytes or ankylosis) were found in the unblinded (48/109, 44%) as compared to the blinded (10/25, 28.6%) group.
Conclusion: Despite lower mean mSASSS baseline values, higher mean mSASSS progression was found with the unblinded approach, while in the shift analysis this approach was more specific, confirming the absence of ‘improvement’ over time.
To cite this abstract in AMA style:Baraliakos X, Rios Rodriguez V, Torgutalp M, Dilbaryan A, Haibel H, Verba M, Sieper J, Braun J, Rudwaleit M, Poddubnyy D. Structural Damage in Axial Spondyloarthritis: Is There a Preferred Way to Assess Progression over Time? [abstract]. Arthritis Rheumatol. 2021; 73 (suppl 9). https://acrabstracts.org/abstract/structural-damage-in-axial-spondyloarthritis-is-there-a-preferred-way-to-assess-progression-over-time/. Accessed January 27, 2023.
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