Abstract
ObjectiveTo investigate the influence of patient characteristics on the course of spinal radiographic progression in a large prospective longitudinal cohort study of ankylosing spondylitis (AS) patients treated long-term with TNF-α inhibitors.MethodsConsecutive patients from the Groningen Leeuwarden AS (GLAS) cohort starting TNF-α inhibitors with spinal radiographs at least available at baseline and 6 years of follow-up were included. Radiographs were scored using mSASSS by two independent readers. Generalized estimating equations (GEE) were used to explore the associations between baseline characteristics and spinal radiographic progression. The course of radiographic progression in patients with and without risk factors for poor radiographic outcome was investigated using different time models (linear and non-linear). Single linear imputation was used in case of missing radiographic data at the intermediate (2 or 4 years) follow-up visits.Results80 AS patients were included with mean baseline mSASSS 8.7±13.3. Baseline syndesmophytes, male gender, older age, longer symptom duration, smoking, and higher BMI were significantly associated with more radiographic damage over time. GEE analysis in patients with these risk factors revealed that radiographic progression followed a non-linear course with mean mSASSS progression rates reducing from max. 2.8 units over 0–2 years to min. 0.9 units over 4–6 years. The GEE model revealed a linear course with overall very low progression (≤1 mSASSS units/2yrs) in patients without risk factors. Complete case analysis in 53 patients showed similar results.ConclusionAS patients at risk of poor radiographic outcome showed the highest but diminishing spinal radiographic progression during long-term treatment with TNF-α inhibitors.
Highlights
In view of the clinical evaluation of new potential biological therapies in axial spondyloarthritis including ankylosing spondylitis (AS), it is important to identify which patients are at risk for radiographic progression
In addition to baseline risk factors, previous cohort studies in axSpA patients, mainly treated with non-steroidal anti-inflammatory drugs (NSAIDs), have demonstrated that spinal radiographic progression is associated with disease activity over time.[10,11]
In the German Spondyloarthritis Inception Cohort (GESPIC), mean AS disease activity scale (ASDAS), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) over 2 years were significantly associated with spinal radiographic progression during these 2 years.[10]
Summary
In view of the clinical evaluation of new potential biological therapies in axial spondyloarthritis (axSpA) including ankylosing spondylitis (AS), it is important to identify which patients are at risk for radiographic progression. In addition to baseline risk factors, previous cohort studies in axSpA patients, mainly treated with non-steroidal anti-inflammatory drugs (NSAIDs), have demonstrated that spinal radiographic progression is associated with disease activity over time.[10,11] In the German Spondyloarthritis Inception Cohort (GESPIC), mean AS disease activity scale (ASDAS), erythrocyte sedimentation rate (ESR), and CRP over 2 years were significantly associated with spinal radiographic progression during these 2 years.[10] In the historical Outcomes in AS International Study (OASIS), a longitudinal relationship was found between spinal radiographic progression and assessments of disease activity over a follow-up period up to 12 years. Bath AS disease activity index (BASDAI), ASDAS, and CRP at the start of a 2-year time interval were significantly associated with radiographic progression during the 2 years.[11]
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