Inflammatory or Neuropathic Pain: Characteristics and Their Relationships with Disease Activity and Functional Status in Axial Spondyloarthritis Patients

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.

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

OBJECTIVES

The aim of this study was to evaluate the relationship between the presence of neuropathic pain (NeP), disease activity scores and biologic drug-switching decisions in the subjects with axial spondyloarthritis (axSpA) receiving biologic treatment.

METHODS

PainDETECT Questionnaire was used to evaluate the presence of NeP in the patients with axSpA aged ≥18 years who had been receiving biologic treatment for at least 6 months. The relationships between disease activity scores, inflammatory markers, life quality index, biologic drug-switching decisions and the presence of NeP were analyzed.

RESULTS

A total number of 175 patients with axSpA [ankylosing spondylitis (AS) (n:150) and non-radiographic axSpA (nr-axSpA) (n:25)] were enrolled in the study. NeP was detected in 41.7% of the patients and it was more common in females than in males (p:0.009). PainDETECT scores were positively correlated with disease activity scores, but they were not correlated with inflammatory marker levels. NeP was found to be significantly more common in whom the biologics had been switched 3 or more times (p:0.007). PainDETECT scores were higher and NeP was more prevalent (p:0.028) in the patients for whom drug-switching decisions had been made due to primary or secondary unresponsiveness.

CONCLUSION

NeP is more common than estimated in the patients with axSpA and current disease activity scores are insufficient to make a distinction between NeP and inflammatory pain. NeP is a confounding factor in the evaluation of treatment response to biologic agents. In the subjects with AS and nr-axSpA with primary or secondary treatment unresponsiveness, the presence of NeP must be considered before biologic drug-switching decisions. Key Points • Neuropathic pain (NeP) is common in subjects with AxSpA treated with multiple biologic agents. • Current disease activity scores for AxSpA are insufficient to make a differentiation between NeP and inflammatory pain. • NeP is a confounding factor in the evaluation of treatment response to biologic agents. • Patients with AxSpA should be re-evaluated in terms of the presence of neuropathic pain before making biologic drug-switching decisions.

Rapid improvement in spinal pain in patients with axial spondyloarthritis treated with secukinumab: primary results from a randomized controlled phase-IIIb trial

BACKGROUND

This study aimed to evaluate the efficacy and safety of secukinumab 150 mg compared with placebo in the management of spinal pain and disease activity in patients with axial spondyloarthritis (axSpA) at Week 8 and up to Week 24.

METHODS

Patients (n = 380) with active axSpA were randomized (3:1) to secukinumab 150 mg (Group A) or placebo (Group B). At Week 8, patients from Group A with an average spinal pain score <4 were defined as responders and were re-assigned to secukinumab 150 mg (Arm A1); whereas non-responders were re-randomized to secukinumab 150/300 mg (Arm A2/A3). Patients from Group B were re-randomized (1:1) to secukinumab 150/300 mg (Arm B1/B2).

RESULTS

At Week 8, the odds of achieving an average spinal pain score of <4 were significantly higher for patients on secukinumab 150 mg than for patients on placebo (odds ratio (OR): 1.89; 95% confidence interval (CI): 1.08-3.33; p = 0.0264). Further reductions in spinal pain were observed across treatment groups up to Week 24. Pronounced improvements were also observed in other disease activity measurements, such as Bath Ankylosing Spondylitis Disease Activity Index and Ankylosing Spondylitis Disease Activity Score. Responders from Group A showed the highest improvements for all measured parameters of spinal pain compared with the other arms. No new or unexpected safety signals were observed.

CONCLUSION

Secukinumab provided rapid and significant improvement in spinal pain at Week 8 which was sustained or increased further up to Week 24 in patients with axSpA.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03136861. Registered May 2, 2017.

Methods to discriminate between mechanism-based categories of pain experienced in the musculoskeletal system: a systematic review

ABSTRACT

Mechanism-based classification of pain has been advocated widely to aid tailoring of interventions for individuals experiencing persistent musculoskeletal pain. Three pain mechanism categories (PMCs) are defined by the International Association for the Study of Pain: nociceptive, neuropathic, and nociplastic pain. Discrimination between them remains challenging. This study aimed to build on a framework developed to converge the diverse literature of PMCs to systematically review methods purported to discriminate between them; synthesise and thematically analyse these methods to identify the convergence and divergence of opinion; and report validation, psychometric properties, and strengths/weaknesses of these methods. The search strategy identified articles discussing methods to discriminate between mechanism-based categories of pain experienced in the musculoskeletal system. Studies that assessed the validity of methods to discriminate between categories were assessed for quality. Extraction and thematic analysis were undertaken on 184 articles. Data synthesis identified 200 methods in 5 themes: clinical examination, quantitative sensory testing, imaging, diagnostic and laboratory testing, and pain-type questionnaires. Few methods have been validated for discrimination between PMCs. There was general convergence but some disagreement regarding findings that discriminate between PMCs. A combination of features and methods, rather than a single method, was generally recommended to discriminate between PMCs. Two major limitations were identified: an overlap of findings of methods between categories due to mixed presentations and many methods considered discrimination between 2 PMCs but not others. The results of this review provide a foundation to refine methods to differentiate mechanisms for musculoskeletal pain.

Association between clinical characteristics and pain relief in patients with axial spondyloarthritis treated with non-steroidal anti-inflammatory drugs

Objectives

The aim of this study was to evaluate pain relief in axial spondyloarthritis (axSpA) patients treated with non-steroidal anti-inflammatory drugs (NSAIDs) and to investigate the relation of the demographic, clinical, and psychological characteristics with pain relief.

Patients and methods

Between February 2017 and December 2019, a total of 94 patients (61 males, 33 females; mean age: 28.3±8.1 years; range, 14 to 54 years) who were diagnosed with axSpA and treated with NSAIDs were included. The patients were assessed at baseline and at three months. A reduction of 30% in the Numeric Rating Scale (NRS) indicates a clinically meaningful improvement. The patients were divided into the relief group (≥30% improvement in NRS) and non-relief group (<30% improvement). Potential influential factors for pain relief such as neuropathic pain (NP), disease activity, function, pain catastrophizing, and pain self-efficacy were assessed. The relationship between patients’ characteristics and pain relief was analyzed.

Results

Seventy-two (76.6%) patients achieved pain relief. These patients had significantly higher baseline erythrocyte sedimentation rate, C-reactive protein, and lower percentage of NP. There was no significant difference between the two groups in function, pain catastrophizing, and pain self-efficacy. Multiple logistic regression analysis revealed that patients with NP were less likely to achieve pain relief (odds ratio [OR]: 3.531, 95% confidence interval [CI]: 1.155-10.789; p=0.027).

Conclusion

Pain relief is still insufficient in some axSpA patients, despite the administration of NSAIDs. The presence of NP is significantly associated with poor pain relief. Alternative medications instead of NSAIDs are needed to achieve optimal pain relief, when NP is diagnosed.

The Neuropathic Pain Features in Psoriatic Arthritis: A Cross-sectional Evaluation of Prevalence and Associated Factors

OBJECTIVE

To evaluate the prevalence and factors associated with the neuropathic pain features in a cohort of patients with psoriatic arthritis (PsA).

METHODS

A cross-sectional evaluation was conducted in consecutive patients having PsA with prevalent peripheral joint involvement, referred to 3 rheumatological centers. For each patient, a comprehensive assessment of disease activity, physical function, and disease effect was carried out. The presence of comorbid fibromyalgia syndrome (FMS) was evaluated. Acute-phase reactants were also recorded. The neuropathic pain features were investigated through the PainDETECT Questionnaire (PDQ). A logistic regression analysis was therefore conducted using the PDQ as the dependent variable.

RESULTS

The final evaluation included 118 patients. A comorbid FMS was detectable in 30 of the 118 patients with PsA (25.4%). Probable characteristics of neuropathic pain (PDQ ≥ 19) were found in 30 (25.4%) patients overall, ambiguous (PDQ > 12 and < 19) in 21 (17.8%) patients, and unlikely (PDQ ≤ 12) in 67 (56.8%) patients. Using logistic regression analysis, the only independent variable among those investigated that could explain the neuropathic pain features was the presence of a comorbid FMS (p = 0.0127). Excluding patients with comorbid FMS, an association with disability (measured by Health Assessment Questionnaire-Disability Index) emerges (p = 0.0489). In patients with PsA and comorbid FMS, PDQ scores were significantly higher than in patients without comorbid FMS.

CONCLUSION

Neuropathic pain features are common in patients with PsA, and the presence of pain sensitization (comorbid FMS) seems to be its main predictor.