Discrete Trajectories of Resolving and Persistent Pain in People With Rheumatoid Arthritis Despite Undergoing Treatment for Inflammation: Results From Three UK Cohorts

Longitudinal Relationship Between Pain and Depression in People With Inflammatory Arthritis: A Narrative Review

As many patients with inflammatory arthritis (IA) have chronic pain, understanding how to best assess and manage pain in IA is a priority. Comorbid depression is prevalent in adults with IA, affecting 15% to 39% of people. Although pain and depression are thought to be associated in IA, this concept is largely based on cross-sectional data. To better understand potential causality, longitudinal studies are required. This narrative review examines the relationship between pain and depression in patients with IA participating in observational longitudinal studies (spanning association strengths, direction of effect, and causal factors) and summarizes the literature on causal pathways in general populations alongside guideline recommendations/systematic reviews on assessing pain/depression in IA. Fourteen longitudinal studies in IA largely indicate an association between pain and depression, albeit with a small-to-modest effect size and a focus on pain intensity. This relationship appears to be bidirectional. Evidence on causal pathways is sparse in IA and limited in non-IA populations (with structural/function brain changes, altered sensory/pain thresholds, and sleep disturbance implicated) highlighting a need for further research. Although many patient-reported outcome measures exist to assess pain and depression in IA, evidence for their psychometric properties is often limited, and IA guidelines offer incomplete advice on pain/depression assessment. A simple approach of using a single-item pain intensity score (eg, a Numeric Rating Scale, which has strong clinimetric properties) in routine IA consultations, with screening for depression where relevant, appears appropriate. Further research is needed to understand how this could be achieved in different health care settings.

Resolution of inflammation during rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes synovial joint inflammation as well as bone destruction and erosion, typically characterized by joint pain, swelling, and stiffness, with complications and persistent pain after remission posing a significant health burden for RA patients. The etiology of RA has not yet been fully elucidated, but a large number of studies have shown that the initiation of inflammation in RA is closely related to T-cell activation, the production of a variety of pro-inflammatory cytokines, macrophage M1/M2 imbalance, homeostatic imbalance of the intestinal flora, fibroblast-like synoviocytes (FLSs) and synovial tissue macrophages (STMs) in the synovial lumen of joints that exhibit an aggressive phenotype. While the resolution of RA is less discussed, therefore, we provided a systematic review of the relevant remission mechanisms including blocking T cell activation, regulating macrophage polarization status, modulating the signaling pathway of FLSs, modulating the subpopulation of STMs, and inhibiting the relevant inflammatory factors, as well as the probable causes of persistent arthritis pain after the remission of RA and its pain management methods. Achieving resolution in RA is crucial for improving the quality of life and long-term prognosis of patients. Thus, understanding these mechanisms provide novel potential for further drug development and treatment of RA.

Pharmacological pain management in patients with rheumatoid arthritis: a narrative literature review

BACKGROUND

Pain is a major challenge for patients with rheumatoid arthritis (RA), with many people suffering chronic pain. Current RA management guidelines focus on assessing and reducing disease activity using disease-modifying anti-rheumatic drugs (DMARDs). Consequently, pain care is often suboptimal, with growing evidence that analgesics are widely prescribed to patients with RA, despite potential toxicities and limited evidence for efficacy. Our review provides an overview of pharmacological treatments for pain in patients with RA, summarising their efficacy and use.

FINDINGS

Thirteen systematic reviews of drug efficacy for pain in patients with RA were included in this review. These showed moderate- to high-quality evidence from clinical trials in more contemporary time-periods (mainly 1990s/2000s for synthetic DMARDs and post-2000 for biological/targeted synthetic DMARDs) that, in patients with active RA, short-term glucocorticoids and synthetic, biologic, and targeted synthetic DMARDs have efficacy at reducing pain intensity relative to placebo. In contrast, they showed low-quality evidence from trials in more historical time-periods (mainly in the 1960s-1990s for opioids and paracetamol) that (aside from naproxen) analgesics/neuromodulators provide any improvements in pain relative to placebo, and no supportive evidence for gabapentinoids, or long-term opioids. Despite this evidence base, 21 studies of analgesic prescribing in patients with RA consistently showed substantial and sustained prescribing of analgesics, particularly opioids, with approximately one quarter and > 40% of patients receiving chronic opioid prescriptions in each year in England and North America, respectively. Whilst NSAID prescribing had fallen over time across countries, gabapentinoid prescribing in England had risen from < 1% of patients in 2004 to approximately 10% in 2020. Prescribing levels varied substantially between individual clinicians and groups of patients.

CONCLUSIONS

In patients with active RA, DMARDs have efficacy at reducing pain, supporting the role of treat-to-target strategies. Despite limited evidence that analgesics improve pain in patients with RA, these medicines are widely prescribed. The reasons for this are unclear. We consider that closing this evidence-to-practice gap requires qualitative research exploring the drivers of this practice, high-quality trials of analgesic efficacy in contemporary RA populations, alongside an increased focus on pain management (including pharmacological and non-pharmacological options) within RA guidelines.

Pain management in people with inflammatory arthritis: British Society for Rheumatology guideline scope

Pain is a common symptom in people with inflammatory arthritis (IA), which has far-reaching impacts on their lives. Recent electronic health record studies demonstrate that UK-based pain care in people with IA commonly involves the prescribing of long-term opioids and gabapentinoids, despite an absence of trial evidence for their efficacy. Patient surveys suggest that non-pharmacological pain management is underused. A UK-specific guideline on pain management for people with IA is required to resolve this. This scoping document outlines the context and prioritized clinical questions for the first British Society for Rheumatology (BSR) guideline on pain management for people with IA. The guideline aims to provide evidence-based recommendations on how pain can be best managed in people with IA (including its assessment, and pharmacological and non-pharmacological treatments), ensuring that people with IA in the UK are offered evidence-based pain management strategies. The guideline is for healthcare professionals involved in the care of people with IA of all ages and genders, people with IA and their families and carers, NHS managers and healthcare commissioners, and other relevant stakeholders such as patient organizations. It will be developed using the methods outlined in the BSR's 'Creating Clinical Guidelines' protocol.

An interdisciplinary perspective on peripheral drivers of pain in rheumatoid arthritis

Pain is one of the most debilitating symptoms of rheumatoid arthritis (RA), and yet remains poorly understood, especially when pain occurs in the absence of synovitis. Without active inflammation, experts most often attribute joint pain to central nervous system dysfunction. However, advances in the past 5 years in both immunology and neuroscience research suggest that chronic pain in RA is also driven by a variety of abnormal interactions between peripheral neurons and mediators produced by resident cells in the local joint environment. In this Review, we discuss these novel insights from an interdisciplinary neuro-immune perspective. We outline a potential working model for the peripheral drivers of pain in RA, which includes autoantibodies, resident immune and mesenchymal cells and their interactions with different subtypes of peripheral sensory neurons. We also offer suggestions for how future collaborative research could be designed to accelerate analgesic drug development.

Predictors for severe persisting pain in rheumatoid arthritis are associated with pain origin and appraisal of pain

OBJECTIVES

To determine the proportion of patients with rheumatoid arthritis (RA) with severe persisting pain and to identify predictive factors despite treatment-controlled disease activity.

METHODS

This prospective multicentre study included outpatients with RA scheduled for escalation of anti-inflammatory treatment due to active disease and severe pain (Disease Activity Score 28 (DAS28)>3.2 and Visual Analogue Scale (VAS)>50). At week 24, patients were stratified into reference group (DAS28 improvement>1.2 or DAS28≤3.2 and VAS pain score<50), non-responders (DAS28 improvement≤1.2 and DAS28>3.2, regardless of VAS pain score) and persisting pain group (DAS28 improvement>1.2 or DAS28≤3.2 and VAS pain score≥50). The former two subgroups ended the study at week 24. The latter continued until week 48. Demographic data, DAS28-C reactive protein, VAS for pain, painDETECT Questionnaire (PD-Q) to identify neuropathic pain (NeP) and the Pain Catastrophising Scale were assessed and tested for relation to persisting pain.

RESULTS

Of 567 patients, 337 (59.4%) were classified as reference group, 102 (18.0%) as non-responders and 128 (22.6%) as patients with persisting pain. 21 (8.8%) responders, 28 (35.0%) non-responders and 27 (26.5%) persisting pain patients tested positive for NeP at week 24. Pain catastrophising (p=0.002) and number of tender joints (p=0.004) were positively associated with persisting pain at week 24. Baseline PD-Q was not related to subsequent persisting pain.

CONCLUSIONS

Persisting and non-nociceptive pain occur frequently in RA. Besides the potential involvement of NeP, pain catastrophising and a higher number of tender joints coincide with persisting pain.

Google Internet searches related to inflammatory arthritis: An observational study using Google Trends data

OBJECTIVE

The Internet has transformed how patients access health information. We examined Google search engine data to understand which aspects of health are most often searched for in combination with inflammatory arthritis (IA).

METHODS

Using Google Trends data (2011-2022) we determined the relative popularity of searches for 'patient symptoms' (pain, fatigue, stiffness, mood, work) and 'treat-to-target' (disease-modifying drugs, steroids, swelling, inflammation) health domains made with rheumatoid arthritis (RA), psoriatic arthritis (PsA), and axial spondyloarthritis (AxSpA) in the UK/USA. Google Trends normalises searches by popularity over time and region, generating 0-100 scale relative search volumes (RSV; 100 represents the time-point with most searches). Up to five search term combinations can be compared.

RESULTS

In all IA forms, pain was the most popular patient symptom domain. UK/USA searches for pain gave mean RSVs of 58/79, 34/51, and 39/63 with RA, PsA, and AxSpA; mean UK/USA RSVs for other patient symptom domains ranged 2-7/2-8. Methotrexate was the most popular treat-to-target search term with RA/PsA in the UK (mean 28/21) and USA (mean 63/33). For AxSpA, inflammation was most popular (mean UK/USA 9/34). Searches for pain were substantially more popular than searches for methotrexate in RA and PsA, and inflammation in AxSpA. Searches increased over time.

CONCLUSIONS

Pain is the most popular search term used with IA in Google searches in the UK/USA, supporting surveys/qualitative studies highlighting the importance of improving pain to patients with IA. Routine pain assessments should be embedded within treat-to-target strategies to ensure patient perspectives are considered.

Protocol for the development of a tool to map systemic sclerosis pain sources, patterns, and management experiences: a Scleroderma Patient-centered Intervention Network patient-researcher partnership

INTRODUCTION

Systemic sclerosis (SSc) is a rare, complex autoimmune rheumatic disease with multiple factors that contribute to pain. People with SSc emphasize the effect pain has on their quality of life, but no studies have systematically examined the frequency and relative importance of different SSc pain sources, patterns of pain from different sources, and pain management experiences. Our objectives are to (1) develop a tool, jointly with researchers, health care providers, and patients, to map sources of pain in SSc, determine patterns of pain from different sources, and understand pain management experiences; and (2) administer the final tool version to participants in the large multinational Scleroderma Patient-centered Intervention Network (SPIN) Cohort.

METHODS

First, we will use validated pain assessment tools as templates to develop an initial version of our pain assessment tool, and we will obtain input from patient advisors to adapt it for SSc. The tool will include questions on pain sources, pain patterns, pain intensity, pain management techniques, and barriers to pain management in SSc. Second, we will conduct nominal group technique sessions with people living with SSc and health care providers who care for people with SSc to further refine the tool. Third, we will conduct individual usability testing sessions with SPIN Cohort participants. Once the tool has been finalized, we will administer it to individuals in the multinational SPIN Cohort, which currently includes over 1,300 active participants from 54 sites in 7 countries. We will perform unsupervised clustering using the KAy-Means for MIxed LArge data (KAMILA) method to identify participant subgroups with similar profiles of pain sources (present or absent) and to evaluate predictors of subgroup membership. We will use latent profile analysis to identify subgroups of participants with similar profiles based on pain intensity scores for each pain source and evaluate predictors.

DISCUSSION

Once completed, our pain assessment tool will allow our team and other researchers to map sources of pain in SSc and to understand pain management experiences of people living with SSc. This knowledge will provide avenues for studies on the pathophysiology of pain in SSc and studies of interventions to improve pain management.

The relationship between pain and depression and anxiety in patients with inflammatory arthritis: a systematic review protocol

Pain is a major challenge for patients with inflammatory arthritis (IA). Depression and anxiety are common comorbidities in IA, associating with worse outcomes. How they relate to pain is uncertain, with existing systematic reviews (a) mainly considering cross-sectional studies, (b) focusing on the relationship between pain and mental health in the context of disease activity/quality of life, and (c) not specifically considering the impact of treating depression/anxiety on pain. This PROSPERO-registered (CRD42023411823) systematic review will address this knowledge-gap by synthesizing evidence to summarise the associations (and potential mediators) between pain and depression/anxiety and evaluate the impact of treating co-morbid depression/anxiety on pain in IA. Relevant databases will be searched, articles screened and their quality appraised (using Joanna Briggs Institute critical appraisal tools) by two reviewers. Eligible studies will include adults with rheumatoid arthritis or spondyloarthritis, be a clinical trial or observational study, and either (a) report the relationship between pain and depression/anxiety (observational studies/baseline trials), or (b) randomise participants to a pharmacological or psychological treatment to manage depression/anxiety with a pain outcome as an endpoint (trials). To synthesise data on the association between pain and depression/anxiety, where available adjusted coefficients from regression models will be pooled in a random-effects meta-analysis. A synthesis without meta-analysis will summarise mediators. To evaluate the impact of treating depression/anxiety on pain, endpoint mean differences between treatment arms will be combined in a random-effects meta-analysis. Through understanding how depression/anxiety contribute to pain in IA, our review has the potential to help optimise approaches to IA pain.

Mechanisms of chronic pain in inflammatory rheumatism: the role of descending modulation

ABSTRACT

Persistent pain despite satisfactory disease treatment is frequent in rheumatoid arthritis (RA) and spondyloarthritis (Spa) and may result from specific changes in central pain processing. We assessed these mechanisms further by systematically comparing thermal pain thresholds and conditioned pain modulation (CPM) between patients with active RA or Spa and healthy controls. We included 50 patients with RA and 50 patients with Spa and 100 age-matched and sex-matched controls. Heat and cold pain thresholds (HPT-CPT) were measured on the dominant forearm, and CPM was assessed by applying conditioning stimuli (immersion in a cold-water bath) to one foot and the nondominant hand in 2 successive randomized sequences. Descending pain modulation was assessed as the difference in HPTs (in °C) before and after conditioning. Larger HPT differences (ie, a larger CPM effect) reflected more efficient descending inhibition. Potential associations between changes in CPM and clinical data, including disease activity, pain intensity, and psychological and functional variables, were systematically assessed. Heat pain threshold and cold pain threshold were similar in patients and controls. The mean CPM effect was significantly weaker in patients than that in controls for conditioning applied to either the foot (0.25°C ±2.57 vs 2.79°C ±2.31; P < 0.001) or the nondominant hand (0.57°C ±2.74 vs 2.68°C ±2.12; P < 0.001). The smaller CPM effect in patients was correlated with average pain intensity, but not with disease activity or other clinical characteristics, suggesting a significant pathophysiological role for changes in endogenous pain modulation in the mechanisms of chronic pain associated with inflammatory rheumatism.

How Does Job Insecurity and Workplace Activity Limitations Relate to Rheumatic Disease Symptom Trajectories in Young Adulthood? A Longitudinal Study

OBJECTIVE

Workplace and labor market conditions are associated with the health of the working population. A longitudinal study was conducted among young adults with rheumatic disease to examine workplace activity limitations and job insecurity and their relationship with disease symptom trajectories.

METHODS

Three online surveys were administered to young adults with rheumatic disease over 27 months. Self-reported data on pain, fatigue, and disease activity were collected. Workplace activity limitations and job insecurity were measured. Group-based discrete mixture models determined pain, fatigue, and disease activity trajectory groups. Robust Poisson regression models were fitted to examine the relationship among workplace activity limitations, job insecurity, and trajectory group membership.

RESULTS

In total, 124 participants (mean ± SD age 29 ± 4.5 years) with rheumatic disease were recruited. At baseline, participants reported considerable workplace activity limitations (10.35 ± 5.8), and 36% of participants indicated experiencing job insecurity. We identified 2 latent rheumatic disease symptom trajectory groups. The first group had high persistent pain, fatigue, or disease activity; the second group had low persistent disease symptoms over time. Greater workplace activity limitations were associated with an increased relative risk (RR) of being in the high persistent severe pain (RR 1.02 [95% confidence interval (95% CI) 1.01, 1.03]), fatigue (RR 1.02 [95% CI 1.01, 1.03]), and disease activity trajectory groups (RR 1.02 [95% CI 1.01, 1.03]). Job insecurity was associated with an increased RR of membership in the high persistent pain (RR 1.14 [95% CI 1.04, 1.25]) and disease activity trajectory groups (RR 1.11 [95% CI 1.00, 1.22]).

CONCLUSION

Workplace activity limitations and job insecurity represent working conditions that are associated with the health of young adults with rheumatic disease and should be examined as potential targets for intervention.

Exploring the disparity between inflammation and disability in the 10-year outcomes of people with rheumatoid arthritis

OBJECTIVES

To identify groups of people with RA with different disability trajectories over 10 years, despite comparable levels of inflammation.

METHODS

Data for this analysis came from three European prospective cohort studies of people with RA [Norfolk Arthritis Register (NOAR), Early RA Network (ERAN), Étude et Suivi des Polyarthrites Indifférenciées Récentes (ESPOIR)]. Participants were assessed regularly over 8 (ERAN) to 10 (NOAR/ESPOIR) years. Inclusion criteria were: recruited after 1 January 2000, <24 months baseline symptom duration, and disability (HAQ) and inflammation [two-component DAS28 (DAS28-2C)] recorded at baseline and at one other follow-up. People in each cohort also completed patient-reported outcome measures at each assessment (pain, fatigue, depressive symptoms). Group-based trajectory models were used to identify distinct groups of people with similar HAQ and DAS28-2C trajectories over follow-up.

RESULTS

This analysis included 2500 people with RA (NOAR: 1000, ESPOIR: 766, ERAN: 734). ESPOIR included more women and the participants were younger [mean (standard deviation) age: NOAR: 57.1 (14.6), ESPOIR: 47.6 (12.5), ERAN: 56.8 (13.8); women: NOAR: 63.9%, ESPOIR: 76.9%, ERAN: 69.1%). Within each cohort, two pairs of trajectories following the hypothesized pattern (comparable DAS28-2Cs but different HAQs) were identified. Higher pain, fatigue and depressive symptoms were associated with increased odds of being in the high HAQ trajectories.

CONCLUSION

Excess disability is persistent in RA. Controlling inflammation may not be sufficient to alleviate disability in all people with RA, and effective pain, fatigue and mood management may be needed in some groups to improve long-term function.

Smoking, alcohol consumption and disease-specific outcomes in rheumatic and musculoskeletal diseases (RMDs): systematic reviews informing the 2021 EULAR recommendations for lifestyle improvements in people with RMDs

BACKGROUND

A EULAR taskforce was convened to develop recommendations for lifestyle behaviours in rheumatic and musculoskeletal diseases (RMDs). The aim of this paper was to review the literature on the relationship between smoking and alcohol consumption with regard to RMD-specific outcomes.

METHODS

Two systematic reviews were conducted to identify systematic reviews and meta-analyses, published between 2013 and 2018, related to smoking and alcohol consumption in seven RMDs: osteoarthritis (OA), rheumatoid arthritis (RA), systemic lupus erythematosus, axial spondyloarthritis (axSpA), psoriatic arthritis (PsA), systemic sclerosis (SSc) and gout. Two additional systematic reviews were performed to identify original longitudinal studies on smoking and alcohol consumption and disease-specific outcomes.

RESULTS

Nine reviews and 65 original studies on smoking as well as two reviews and 14 original studies on alcohol consumption met the inclusion criteria. While most studies were moderate/poor quality, smoking was significantly associated with poorer outcomes: cardiovascular comorbidity; poorer response to RA treatment; higher disease activity and severity in early RA; axSpA radiographic progression. Results were heterogeneous for OA while there was limited evidence for PsA, SSc and gout. Available studies on alcohol mainly focused on RA, reporting a positive association between alcohol intake and radiographic progression. Five studies assessed alcohol consumption in gout, reporting a significant association between the number and type of alcoholic beverages and the occurrence of flares.

CONCLUSION

Current literature supports that smoking has a negative impact on several RMD-specific outcomes and that moderate or high alcohol consumption is associated with increased risk of flares in RA and gout.

The autoimmune aetiology of unexplained chronic pain

Chronic pain is the leading cause of life years lived with disability worldwide. The aetiology of most chronic pain conditions has remained poorly understood and there is a dearth of effective therapies. The WHO ICD-11 has categorised unexplained chronic pain states as 'chronic primary pains' (CPP), which are further defined by their association with significant distress and/or dysfunction. The new mechanistic term, 'nociplasticic pain' has been developed to illustrate their presumed generation by a structurally intact, but abnormally functioning nociceptive system. Recently, researchers have unravelled the surprising, ubiquitous presence of pain-sensitising autoantibodies in four investigated CPP indicating autoimmune causation. In persistent complex regional pain syndrome, fibromyalgia syndrome, chronic post-traumatic limb pain, and non-inflammatory joint pain associated with rheumatoid arthritis, passive transfer experiments have shown that either IgG or IgM antibodies from patient-donors cause symptoms upon injection to rodents that closely resemble those of the clinical disorders. Targets of antibody-binding and downstream effects vary between conditions, and more research is needed to elucidate the molecular and cellular details. The central nervous system appears largely unaffected by antibody binding, suggesting that the clinically evident CNS symptoms associated with CPP might arise downstream of peripheral processes. In this narrative review pertinent findings are described, and it is suggested that additional symptom-based disorders might be examined for the contribution of antibody-mediated autoimmune mechanisms.

Identifying multiple knee pain trajectories and the prediction of opioid and NSAID medication used: A latent class growth approach

BACKGROUND

Knee pain is a major source of distress and disability, with pain progression highly variable between individuals. Previous studies defining pain trajectories have all used a single measure of pain, and these differ across studies. Different measures reflect diverse pain mechanisms. To ascertain the clinical utility of pain trajectories, we explored associations between opioid and non-steroidal anti-inflammatory drug (NSAID) use.

METHODS

We model pain trajectories using two measures-Intermittent and Constant Osteoarthritis Pain (ICOAP) and the painDETECT, in 2141 participants, across 3 waves (the baseline, 1- and 3-year assessments) of the Knee Pain In the Community (KPIC) cohort.

RESULTS

Latent class growth analysis identified six trajectories using ICOAP subscales (High-Stable, Low-Stable, Moderate Worsening, Moderate Recovering, Worsening, and Recovering) and four trajectories using painDETECT (High-stable, Low-stable, Moderate Worsening, and Moderate Recovering). There was a high degree of correspondence between people assigned to pain trajectories between ICOAP intermittent and constant subscales, but less so using painDETECT. Opioid use was associated with ICOAP trajectories only (e.g., High-Stable and Worsening intermittent ICOAP trajectories) and in women.

CONCLUSION

Different measures of pain produce different patterns of pain progression and these are differentially related to medication use. Opioid use is linked to trajectories of pain based on the impact of pain on behavior and not pain symptoms. Thus, managing pain's behavioral impact is more central to understanding opioid use than managing pain symptoms. These findings support more in-depth questioning about the type of pain and its progression in clinical practice.

Fatigue in Early Rheumatoid Arthritis: Data from the Early Rheumatoid Arthritis Network

OBJECTIVES

Fatigue is a disabling symptom in people with Rheumatoid Arthritis (RA). This study aims to describe the prevalence, risk factors and the longitudinal course of fatigue in early RA.

METHODS

Demographic, clinical, quality of life (QoL), comorbidities and laboratory data were from the Early Rheumatoid Arthritis Network (ERAN), a UK multicentre inception cohort of people with RA.Fatigue was measured using the Vitality subscale of SF36 where higher values represented better QoL. Baseline prevalences of fatigue classifications were age and sex standardised. Linear regression, hierarchical growth curve modelling and group-based trajectory modelling (GBTM) were utilized.

RESULTS

At baseline (n = 1236, 67% female, mean age 57), mean Vitality was 41 (SD ± 11), disease duration 11 months (IQR : 7-18). Age and sex standardized prevalence rates of fatigue and severe fatigue were 44% (CI: 39-50) and 19% (CI: 15-23) respectively.Fatigue changed little over 3 years and 5 measurement occasions, ß=-0.13 (-0.23 to -0.02). GBTM identified 2 sub-groups, which we named 'Fatigue' (53%) and 'No-fatigue' (47%) groups. Female sex, worse pain, mental health, and functional ability were associated with greater fatigue and predicted 'Fatigue' group membership (AUROC = 0.81). Objective measures of inflammation-swollen joint count (SJC) and erythrocyte sedimentation rate (ESR) were not significantly associated with fatigue.

CONCLUSIONS

Fatigue is prevalent and persistent in early RA. Diverse characteristics indicative of central mechanisms are associated with persistent fatigue. Management of fatigue might require interventions targeted at central mechanisms in addition to inflammatory disease modification. People who require such interventions might be identified at presentation with early RA.

Comparison of chronic widespread pain prevalence with different criteria in two cohorts of rheumatoid arthritis

Objective

This study aims to investigate chronic widespread pain with the 1990 (CWP1990) and 2019 (CWP2019) definitions 6 years after the onset of rheumatoid arthritis (RA), in one patient cohort with tight controls and one conventional cohort, and factors associated with reporting CWP1990 and CWP2019, respectively.

Methods

A cohort of 80 RA patients with monthly visits to the physician the first 6 months was compared to a cohort of 101 patients from the same clinic with conventional follow-up. Both cohorts had early RA (< 13 months). The prevalence of CWP1990 and the more stringent CWP2019 were in a 6-year follow-up investigated with a questionnaire, including a pain mannequin and a fear-avoidance beliefs questionnaire.

Results

In the tight control cohort, 10% reported CWP2019 after 6 years compared to 23% in the conventional cohort (p = 0.026). There was no difference when using the CWP1990 definition (27% vs 31%, p = 0.546). When adjusted for important baseline data, the odds ratio for having CWP2019 was 2.57 (95% CI 1.02–6.50), in the conventional group compared to the tight control group (p = 0.046). A high level of fear-avoidance behaviour towards physical activity was associated with CWP2019, OR 10.66 (95% CI 1.01–112.14), but not with CWP1990 in the tight control cohort.

Conclusion

A more stringent definition of CWP identifies patients with a more serious pain condition, which potentially could be prevented by an initial tight control management. Besides tight control, caregivers should pay attention to fear-avoidance behaviour and tailor treatment.

Key Points

• CWP2019 is a more stringent definition of chronic widespread pain and identifies patients with a more serious pain condition.

• Patients with a serious pain condition could be helped by frequent follow-ups.

• This study suggests that a special attention of fear-avoidance behaviour towards physical activity in patients with RA is needed.

Sociodemographic determinants in the evolution of pain in inflammatory rheumatic diseases: results from ESPOIR and DESIR cohorts

Objective

To determine whether socio-demographic factors are associated with heterogeneity in pain evolution in inflammatory rheumatic diseases (IRDs) after accounting for disease-specific characteristics in a system with universal health care.

Methods

This analysis included the data from two prospective observational cohorts of early IRDs (ESPOIR for early RA and DESIR for early SpA). Data on pain was measured, respectively, on 13 and 9 occasions spanning 10 and 6 years of follow-up using the Short-Form 36 bodily pain score for 810 participants of ESPOIR, and 679 participants of DESIR. Linear mixed models were used to characterize differences in pain evolution as a function of age (tertiles), sex, ethnicity, education, marital, and professional status, after accounting for disease-related, treatment, lifestyle, and health factors.

Results

While transitioning from early (disease duration ≤6 months for RA and ≤3 years for SpA) to long-standing disease, differences in pain evolution emerged as a function of age (P < 0.001), sex (P = 0.050), and ethnicity (P = 0.001) in RA, and as a function of age (P = 0.048) in SpA; younger age, males, and Caucasians exhibited lower pain in the latter phases of both diseases. Highly educated participants (RA, β = −3.8, P = 0.007; SpA, β = −6.0, P < 0.001) for both diseases, and Caucasians (β = −5.6, P = 0.021) for SpA presented with low pain early in the disease, with no changes throughout disease course.

Conclusion

Being older, female, non-Caucasian and having lower education was found to be associated with worse pain in early and/or long-standing IRDs, despite universally accessible health-care. Early identification of at-risk populations and implementation of multidisciplinary strategies may reduce patient-reported health outcome disparities.

Trial registration registrations

ESPOIR: ClinicalTrials.gov, www.clinicaltrials.gov, NCT03666091. DESIR: ClinicalTrials.gov, www.clinicaltrials.gov, NCT01648907.

Central Aspects of Pain in Rheumatoid Arthritis (CAP-RA): protocol for a prospective observational study

BACKGROUND

Pain and fatigue are persistent problems in people with rheumatoid arthritis. Central sensitisation (CS) may contribute to pain and fatigue, even when treatment has controlled inflammatory disease. This study aims to validate a self-report 8-item questionnaire, the Central Aspects of Pain in Rheumatoid Arthritis (CAP-RA) questionnaire, developed to measure central pain mechanisms in RA, and to predict patient outcomes and response to treatment. A secondary objective is to explore mechanisms linking CS, pain and fatigue in people with RA.

METHODS/DESIGN

This is a prospective observational cohort study recruiting 250 adults with active RA in secondary care. The CAP-RA questionnaire, demographic data, medical history, and patient reported outcome measures (PROMs) of traits associated with central sensitization will be collected using validated questionnaires. Quantitative sensory testing modalities of pressure pain detection thresholds, temporal summation and conditioned pain modulation will be indices of central sensitization, and blood markers, swollen joints and ultrasound scans will be indices of inflammation. Primary data collection will be at baseline and 12 weeks. The test-retest reliability of CAP-RA questionnaire will be determined 1 week after the baseline visit. Pain and fatigue data will be collected weekly via text messages for 12 weeks. CAP-RA psychometric properties, and predictive validity for outcomes at 3 months will be evaluated.

DISCUSSION

This study will validate a simple self-report questionnaire against psychophysical indices of central sensitization and patient reported outcome measures of traits associated with CS in a population of individuals with active RA. The application of this instrument in the clinical environment could provide a mechanism-based stratification tool to facilitate the provision of targeted therapy to individuals with pain and fatigue in RA, alongside treatments that target joint inflammation.

TRIAL REGISTRATION

Clinicaltrials.gov NCT04515589 . Date of registration 17 August 2020.

Predictors of unacceptable pain with and without low inflammation over 5 years in early rheumatoid arthritis-an inception cohort study

Objectives

Pain is a major symptom in patients with rheumatoid arthritis (RA). In early RA, pain is usually due to synovitis, but can also persist despite effective anti-inflammatory treatment. The objective of this study was to investigate the pain course over time and predictors of unacceptable pain and unacceptable pain with low inflammation, in patients with early RA.

Methods

An inception cohort of 232 patients with early RA, recruited in 1995–2005, was followed in a structured programme for 5 years. Pain was assessed using a visual analogue scale (VAS; 0–100). Unacceptable pain was defined as VAS pain > 40 based on the patient acceptable symptom state (PASS) and low inflammation as CRP < 10 mg/l. Baseline predictors of unacceptable pain were evaluated using logistic regression analysis.

Results

Pain improved significantly during the first 6 months, but then remained basically unchanged. Thirty-four per cent of the patients had unacceptable pain 5 years after inclusion. Baseline predictors of unacceptable pain after 5 years were lower swollen joint counts [odds ratio (OR) 0.71 per standard deviation (95% confidence interval (CI) 0.51–0.99)] and higher VAS for pain and global assessment of disease activity. Unacceptable pain with low inflammation after 5 years was negatively associated with anti-CCP antibodies [OR 0.50 (95% CI 0.22–0.98)].

Conclusion

Over one third of the patients had unacceptable pain 5 years after inclusion. Lower swollen joint count was associated with unacceptable pain at 5 years. The results may be explained by the positive effects of treatment on pain related to inflammation. Non-inflammatory long-lasting pain appears to be a greater problem in anti-CCP-negative patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02550-7.

Peripheral and central nervous system alterations in a rat model of inflammatory arthritis

It is consistently reported that in inflammatory arthritis (IA), pain may continue despite well-controlled inflammation, most likely due to interactions between joint pathology and pain pathway alterations. Nervous system alterations have been described, but much remains to be understood about neuronal and central non-neuronal changes in IA. Using a rat model of IA induced by intra-articular complete Freund's adjuvant injection, this study includes a thorough characterization of joint pathology and objectives to identify peripheral innervation changes and alterations in the spinal dorsal horn (DH) that could alter DH excitatory balancing. Male and female rats displayed long-lasting pain-related behavior, but, in agreement with our previous studies, other pathological alterations emerged only at later times. Cartilage vascularization, thinning, and decreased proteoglycan content were not detectable in the ipsilateral cartilage until 4 weeks after complete Freund's adjuvant. Sympathetic and peptidergic nociceptive fibers invaded the ipsilateral cartilage alongside blood vessels, complex innervation changes were observed in the surrounding skin, and ipsilateral nerve growth factor protein expression was increased. In the DH, we examined innervation by peptidergic and nonpeptidergic nociceptors, inhibitory terminal density, the KCl cotransporter KCC2, microgliosis, and astrocytosis. Here, we detected the presence of microgliosis and, interestingly, an apparent loss of inhibitory terminals and decreased expression of KCC2. In conclusion, we found evidence of anatomical, inflammatory, and neuronal alterations in the peripheral and central nervous systems in a model of IA. Together, these suggest that there may be a shift in the balance between incoming and outgoing excitation, and modulatory inhibitory tone in the DH.

Autoimmune regulation of chronic pain

Chronic pain is an unpleasant and debilitating condition that is often poorly managed by existing therapeutics. Reciprocal interactions between the nervous system and the immune system have been recognized as playing an essential role in the initiation and maintenance of pain. In this review, we discuss how neuroimmune signaling can contribute to peripheral and central sensitization and promote chronic pain through various autoimmune mechanisms. These pathogenic autoimmune mechanisms involve the production and release of autoreactive antibodies from B cells. Autoantibodies-ie, antibodies that recognize self-antigens-have been identified as potential molecules that can modulate the function of nociceptive neurons and thereby induce persistent pain. Autoantibodies can influence neuronal excitability by activating the complement pathway; by directly signaling at sensory neurons expressing Fc gamma receptors, the receptors for the Fc fragment of immunoglobulin G immune complexes; or by binding and disrupting ion channels expressed by nociceptors. Using examples primarily from rheumatoid arthritis, complex regional pain syndrome, and channelopathies from potassium channel complex autoimmunity, we suggest that autoantibody signaling at the central nervous system has therapeutic implications for designing novel disease-modifying treatments for chronic pain.

Dorsal horn disinhibition and movement-induced behaviour in a rat model of inflammatory arthritis

OBJECTIVES

Alterations beyond joint inflammation such as changes in dorsal horn (DH) excitability contribute to pain in inflammatory arthritis (IA). More complete understanding of specific underlying mechanisms will be important to define novel targets for the treatment of IA pain. Pre-clinical models are useful, but relevant pain assays are vital for successful clinical translation. For this purpose, a method is presented to assess movement-induced pain-related behaviour changes that was subsequently used to investigate DH disinhibition in IA.

METHODS

IA was induced by intra-articular injection of complete Freund's adjuvant (CFA) in male rats, and weight distribution was assessed before and after walking on a treadmill. To confirm increased activity in nociception-related pathways, fos expression was assessed in the superficial DH, including in nociceptive neurons, identified by neurokinin 1 (NK1) immunoreactivity, and interneurons. Inhibitory terminal density onto NK1+ neurons was assessed and lastly, a cohort of animals was treated for 3 days with gabapentin.

RESULTS

At 4 weeks post-CFA, walking reduced weight distribution to the affected joint and increased DH fos expression, including in NK1+ neurons. Neuronal activity in inhibitory cells and inhibitory terminal density on NK1+ neurons were decreased in CFA-treated animals compared with controls. Treatment with gabapentin led to recovered behaviour and DH neuronal activity pattern in CFA-treated animals.

CONCLUSION

We describe an assay to assess movement-induced pain-related behaviour changes in a rodent IA model. Furthermore, our results suggest that disinhibition may contribute to pain related to movement in IA.

Investigating musculoskeletal health and wellbeing; a cohort study protocol

Background

In an ageing population, pain, frailty and disability frequently coexist across a wide range of musculoskeletal diagnoses, but their associations remain incompletely understood. The Investigating Musculoskeletal Health and Wellbeing (IMH&W) study aims to measure and characterise the development and progression of pain, frailty and disability, and to identify discrete subgroups and their associations. The survey will form a longitudinal context for nested research, permitting targeted recruitment of participants for qualitative, observational and interventional studies; helping to understand recruitment bias in clinical studies; and providing a source cohort for cohort randomised controlled trials.

Methods

IMH&W will comprise a prospective cohort of 10,000 adults recruited through primary and secondary care, and through non-clinical settings. Data collection will be at baseline, and then through annual follow-ups for 4 years. Questionnaires will address demographic characteristics, pain severity (0–10 Numerical Rating Scale), pain distribution (reported on a body Manikin), pain quality (McGill Pain Questionnaire), central aspects of pain (CAP-Knee), frailty and disability (based on Fried criteria and the FRAIL questionnaire), and fracture risk. Baseline characteristics, progression and associations of frailty, pain and disability will be determined. Discrete subgroups and trajectories will be sought by latent class analysis. Recruitment bias will be explored by comparing participants in nested studies with the eligible IMH&W population.

Discussion

IMH&W will elucidate associations and progression of pain, frailty and disability. It will enable identification of people at risk of poor musculoskeletal health and wellbeing outcomes who might be suitable for specific interventions, and facilitate generalisation and comparison of research outcomes between target populations. The study will benefit from a large sample size and will recruit from diverse regions across the UK. Purposive recruitment will enrich the cohort with people with MSK problems with high representation of elderly and unwell people.

Trial registration

Clinicaltrials.gov NCT03696134. Date of Registration: 04 October 2018.