Pain in Axial Spondyloarthritis: Insights from Immunology and Brain Imaging.

Inflammatory back pain is characteristic of spondyloarthritis (SpA); however, this pain may not respond to treatment with NSAIDs or biologics. Pain is multifactorial and a combination of mechanical and inflammatory factors. A growing body of literature examines the impact of emotions on pain in SpA; many patients with this condition suffer from depression and fibromyalgia. Advanced imaging techniques can investigate the interplay of various brain networks in pain perception. Animal models have helped understand the interplay between the immune and nervous systems in pain generation and have highlighted differences in pain perception between the sexes.

Impact of biological therapy on work outcomes in patients with axial spondyloarthritis: results from the British Society for Rheumatology Biologics Register (BSRBR-AS) and meta-analysis.

OBJECTIVES: To quantify, among patients with axial spondyloarthritis (axSpA), the benefit on work outcomes associated with commencing biologic therapy. METHODS: The British Society for Rheumatology Biologics Register in Axial Spondyloarthritis (BSRBRAS) recruited patients meeting Assessment of SpondyloArthritis International Society criteria for axSpA naïve to biological therapy across 83 centres in Great Britain. Work outcomes (measured using the Work Productivity and Activity Impairment Index) were compared between those starting biological therapy at the time of recruitment and those not. Differences between treatment groups were adjusted using propensity score matching. Results from BSRBR-AS were combined with other studies in a meta-analysis to calculate pooled estimates. RESULTS: Of the 577 participants in this analysis who were in employment, 27.9% were starting biological therapy at the time of recruitment. After propensity score adjustment, patients undergoing biological therapy, at 12-month follow-up, experienced significantly greater improvements (relative to non-biological therapy) in presenteeism (-9.4%, 95% CI -15.3% to -3.5%), overall work impairment (-13.9%, 95% CI -21.1% to -6.7%) and overall activity impairment (-19.2%, 95% CI -26.3% to -12.2%). There was no difference in absenteeism (-1.5%, 95% CI -8.0 to 4.9). Despite these improvements, impact on work was still greater in the biological treated cohort at follow-up. In the meta-analysis including 1109 subjects across observational studies and trials, treatment with biological therapy was associated with significantly greater improvements in presenteeism, work impairment and activity impairment, but there was no difference in absenteeism. CONCLUSIONS: There is consistent evidence that treatment with biological therapy significantly improves work productivity and activity impairment in people with axSpA. However, there remain substantial unmet needs in relation to work.

Pain in spondyloarthritis: A neuro-immune interaction.

Pain in spondyloarthritis is usually attributed to inflammation. However, treatment with potent biologic agents that control inflammation does not always control the pain. Pain is hence likely to be multifactorial. Fatigue is another prominent feature of this condition which again tends to respond poorly to potent biologic agents. There is also a growing interest in coexisting fibromyalgia in this group of patients and how this affects response to biologic therapies. Advances in neuroimaging have helped in better understanding the dynamic nature of brain networks in the perception of pain. Animal models have helped in developing concepts of peripheral and central sensitization in pain transmission. This review discusses the neuroimmune basis of pain in ankylosing spondylitis, with an emphasis on brain networks and the complex interactions between the nervous system and the immune system at various levels. It also provides some insights into the differences in pain perception between men and women.