THU0711-HPR Widespread pain in axial spondyloarthritis: clinical importance and gender differences
Authors: T.W. Swinnen, W. Dankaerts, R. Westhovens, K. de Vlam
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Cardinal clinical signs and symptoms of axSpA include inflammatory pain, stiffness and impaired mobility in the axial region and to a lesser extent the peripheral joints. Although these features are thought to reflect local disease processes, bottom-up or top-down amplification of nervous system signalling may alter this relationship and may induce widespread pain.<sup>1</sup> There is a remarkable lack of detailed knowledge on pain areas in axSpA and its clinical relevance is unknown. Also, gender differences in pain area may exist in axSpA and may confound disease activity outcomes. <h3>Objectives</h3> Firstly, pain locations in axial axSpA were detailed and gender differences were assessed. Secondly, the relationship of regional pain definitions as well as widespread pain with clinical outcomes was evaluated. Finally, the role of pain area in the assessment of disease activity was explored, taking gender into account. <h3>Methods</h3> Body charts informed on axial, peripheral articular and non-articular pain in 170 (108 men, 62 women) patients with axSpA. Multivariate odds ratios compared genders. General linear models explored clinical differences in disease activity (BASDAI, Bath Ankylosing Spondylitis Disease Activity Index), activity limitations (BASFI, Bath Ankylosing Spondylitis Functional Index), fear of movement (TSK-11, Tampa Scale for Kinesiophobia 11-item version), anxiety (HADS-A, Hospital Anxiety and Depression Scale subscale anxiety) and depression (HADS-D, HADS subscale depression) between four subgroups classified by widespread non-articular pain (WNAP±) and physician-reported global disease activity (PGDA±). Principal component analysis explored gender differences in the structure of disease activity outcomes. <h3>Results</h3> Axial thoracic pain was least prevalent (lumbar: 74.4%, cervical: 47.6%, cervicothoracic: 47.6%, thoracic: 32.4%), but about three times more likely in women (OR: 2.92, p=0.009). Axial cervicothoracic junction pain spread more diffusely in women (OR: 2.48, p=0.018). Women exhibited a two to three-fold increased likelihood of widespread axial (OR: 3.33, p=0.007) and peripheral articular (OR: 2.34, p=0.023) pain. A subgroup of WNAP+/PGDA- combined with low PGDA (27% of all patients) was associated with worse BASFI, BASDAI, HADS-A and HADS-D in men and worse TSK-11 and HADS-A in women (p&lt;0.05). Disease activity outcomes showed a two-factor structure in women, but not in men. <h3>Conclusions</h3> In patients with axSpA, the location and spread of pain was different between genders and is related to worse clinical status. Based on pain area and physician-reported global disease activity, meaningful clinical subgroups were identified with a remarkably distinct health status. Outcome instruments such as BASDAI should acknowledge gender differences to ensure structural validity. <h3>Reference</h3> [1] Latremoliere A, Woolf CJ. Central sensitization: a generator of pain hypersensitivity by central neural plasticity. J Pain2009;10(9):895–926. <h3>Disclosure of Interest</h3> None declared