Abstract
BackgroundFunctional status and spinal mobility in patients with axial spondyloarthritis (axSpA) are known to be determined both by disease activity and by structural damage in the spine. The impact of structural damage in the sacroiliac joints (SIJ) on physical function and spinal mobility in axSpA has not been studied so far. The objective of the study was to analyze the impact of radiographic sacroiliitis on functional status and spinal mobility in patients with axSpA.MethodsIn total, 210 patients with axSpA were included in the analysis. Radiographs of SIJ obtained at baseline and after 2 years of follow up were scored by two trained readers according to the modified New York criteria grading system (grade 0–4). The mean of two readers’ scores for each joint and a sum score for both SIJ were calculated for each patient giving a sacroiliitis sum score between 0 and 8. The Bath Ankylosing Spondylitis Functional Index (BASFI) and Bath Ankylosing Spondylitis Metrology Index (BASMI) at baseline and after 2 years were used as outcome measures.ResultsLongitudinal mixed model analysis adjusted for structural damage in the spine (modified Stoke Ankylosing Spondylitis Spine Score - mSASSS), disease activity (Bath Ankylosing Spondylitis Disease Activity Index - BASDAI and C-reactive protein level) and gender, revealed an independent association of the sacroiliitis sum score with the BASFI: b = 0.10 (95% CI 0.01–0.19) and the BASMI: b = 0.12 (95% CI 0.03–0.21), respectively, indicating that change by one radiographic sacroiliitis grade in one joint is associated with BASFI/BASMI worsening by 0.10/0.12 points, respectively, independently of disease activity and structural damage in the spine.ConclusionStructural damage in the SIJ might have an impact on functional status and spinal mobility in axSpA independently of spinal structural damage and disease activity.Trial registrationClinicalTrials.gov, NCT01277419. Registered on 14 January 2011.
Highlights
Functional status and spinal mobility in patients with axial spondyloarthritis are known to be determined both by disease activity and by structural damage in the spine
Protopopov et al Arthritis Research & Therapy (2017) 19:240. Axial spondyloarthritis covers both patients with non-radiographic axial spondyloarthritis (axSpA) – often the earlier stage of axSpA – and patients with radiographic axSpA, termed ankylosing spondylitis (AS). The latter is defined by the presence of structural damage in the sacroiliac joints (SIJ) on X-rays according to the modified New York criteria for AS
We investigated the association between structural damage in the SIJ and functional status and spinal mobility in patients with axSpA
Summary
Functional status and spinal mobility in patients with axial spondyloarthritis (axSpA) are known to be determined both by disease activity and by structural damage in the spine. Axial spondyloarthritis (axSpA) covers both patients with non-radiographic (nr) axSpA – often the earlier stage of axSpA – and patients with radiographic axSpA, termed ankylosing spondylitis (AS) The latter is defined by the presence of structural damage in the sacroiliac joints (SIJ) on X-rays according to the modified New York criteria for AS. It was reported previously that functional status and spinal mobility parameters in patients with axSpA are independently determined by irreversible structural damage in the spine, i.e. presence of syndesmophytes and ankylosis, and by potentially reversible disease activity [1,2,3]. Structural damage in the SIJ (such as erosions, joint space alteration and especially ankylosis) might have an impact on mobility and function – a hypothesis that has never been investigated in a wider range of the axSpA spectrum including nr-axSpA and AS.
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