Neuropathic pain in axial spondyloarthropathy is underdiagnosed and a confounding factor in biologic drug-switching decision: a cross-sectional study

Difficult-to-treat axial spondyloarthritis patients

Objectives

This study aimed to formulate D2T (difficult to treat) criteria for axial spondyloarthritis (AxSpA) patients and identify the prevalence of D2T patients and their characteristics.

Patients and methods

The cross-sectional study was conducted with 166 AxSpA patients (93 males, 73 females; mean age: 47.1±12.9 years; range, 19 to 78 years) between February 2023 and March 2023. The criteria were based on patients treated according to the European Alliance of Associations for Rheumatology (EULAR) recommendations for AxSpA. Entry criteria were treatment failure to ≥2 biological/targeted synthetic disease-modifying antirheumatic drugs with two different mechanisms of action or ≥3 biological/targeted synthetic disease-modifying antirheumatic drugs. Potential preliminary factors for D2T criteria were analyzed, and the characteristics of the subjects matching D2T criteria were compared with those of others.

Results

One hundred forty-two ankylosing spondylitis patients and 24 nonradiographic AxSpA patients were included in the study. The rate of fulfilling the D2T criteria was 22.9% (n=38) among AxsPA patients treated with biological agents. The potential D2T criteria were met by 23.2% of ankylosing spondylitis and 20.8% of nonradiographic AxSpA patients. Baseline characteristics, such as sex, age, diagnosis age, occupation, and education, of D2T patients were not statistically different from other patients. The prevalence of fibromyalgia was higher in D2T patients (p<0.001). Disease activity indices and acute phase response indicators were higher and quality of life was worse in D2T patients.

Conclusion

There was a considerable amount of AxSpA patients fulfilling the D2T criteria despite new and effective treatment agents.

Pain in axial spondyloarthritis: role of the JAK/STAT pathway

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that is characterized by new bone formation in the axial musculoskeletal system, with X-ray discriminating between radiographic and non-radiographic forms. Current therapeutic options include non-steroidal anti-inflammatory drugs in addition to biological disease-modifying anti-rheumatic drugs that specifically target tumor necrosis factor-alpha (TNFα) or interleukin (IL)-17. Pain is the most critical symptom for axSpA patients, significantly contributing to the burden of disease and impacting daily life. While the inflammatory process exerts a major role in determining pain in the early phases of the disease, the symptom may also result from mechanical and neuromuscular causes that require complex, multi-faceted pharmacologic and non-pharmacologic treatment, especially in the later phases. In clinical practice, pain often persists and does not respond further despite the absence of inflammatory disease activity. Cytokines involved in axSpA pathogenesis interact directly/indirectly with the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling cascade, a fundamental component in the origin and development of spondyloarthropathies. The JAK/STAT pathway also plays an important role in nociception, and new-generation JAK inhibitors have demonstrated rapid pain relief. We provide a comprehensive review of the different pain types observed in axSpA and the potential role of JAK/STAT signaling in this context, with specific focus on data from preclinical studies and data from clinical trials with JAK inhibitors.

Association of nociplastic and neuropathic pain components with the presence of residual symptoms in patients with axial spondyloarthritis receiving biological disease-modifying antirheumatic drugs

OBJECTIVE

To evaluate the association of nociplastic (NoP) and neuropathic pain (NP) components with residual symptoms in patients with radiographic axial spondyloarthritis (r-axSpA) receiving biological disease-modifying antirheumatic drugs (bDMARDs).

METHODS

78 patients with r-axSpA from the GErman SPondyloarthritis Inception Cohort receiving a bDMARD for at least 3 months were included in this analysis. The Widespread Pain Index (WPI) and the PainDETECT (PD) questionnaire were used to quantify the NoP and the NP components, respectively. Axial Spondyloarthritis Disease Activity Score (ASDAS) and the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) were used as measures of residual symptoms. C reactive protein (CRP) was used as a measure of systemic inflammatory activity. Univariable and multivariable regression analyses of disease activity were performed. The regions of the WPI score and items of the PD score were used for cluster analyses.

RESULTS

Linear multivariable regression analysis showed that WPI and PD were independently associated with ASDAS (b=0.1, 95% CI 0.04 to 0.17, and b=0.05, 95% CI 0.02 to 0.08, respectively) and BASDAI (b=0.24, 95% CI 0.08 to 0.39, and b=0.17, 95% CI 0.1 to 0.25, respectively) in r-axSpA patients receiving stable treatment with bDMARDs. Furthermore, WPI and PD were found to be significantly associated with the presence of relevant residual symptoms as defined by BASDAI ≥4 (OR 1.93, 95% CI 1.09 to 4.15, and OR 1.32, 95% CI 1.04 to 1.85, respectively). The effects were present also in patients with normal level of CRP. Cluster analysis revealed three distinct pain distribution profiles and four specific sensory symptom constellations allowing differentiation of different pain subtypes.

CONCLUSION

Both NoP and NP components seem to be associated with residual symptoms in patients with r-axSpA receiving treatment with bDMARDs.