Predictors of change in bodily pain in early rheumatoid arthritis: an inception cohort study

Persistent pain and its predictors after starting anti-tumour necrosis factor therapy in psoriatic arthritis: what is the role of inflammation control?

OBJECTIVE

While considerable focus has been placed on pain due to inflammation in psoriatic arthritis (PsA), less is reported on pain despite inflammation control. Here, we aimed to investigate the occurrence/predictors of persistent pain, including non-inflammatory components, after starting anti-tumour necrosis factor (anti-TNF) therapy.

METHOD

Bionaïve PsA patients starting a first anti-TNF therapy 2004-2010 were identified (South Swedish Arthritis Treatment Group register; N = 351). Outcomes included unacceptable pain [visual analogue scale (VAS) pain > 40 mm], and unacceptable pain despite inflammation control (refractory pain; VAS pain > 40 mm + C-reactive protein < 10 mg/L + ≤ 1 swollen joint of 28), assessed at 0, 3, 6, and 12 months. Baseline predictors were estimated by logistic regression.

RESULTS

Upon starting anti-TNF therapy, 85% of patients reported unacceptable pain, falling to 43% at 3 months and then remaining stable. After 12 months, refractory pain constituted 63% of all unacceptable pain. Higher baseline VAS pain/global, worse physical function and lower health-related quality-of-life were associated with a higher risk of unacceptable/refractory pain at 12 months. More swollen joints and higher evaluator's global assessment were associated with a lower risk of 12-month refractory pain.

CONCLUSIONS

A substantial proportion of PsA patients reported unacceptable pain throughout the first anti-TNF treatment year. At 12 months, refractory pain constituted about two-thirds of this remaining pain load. More objective signs of inflammation at anti-TNF initiation were associated with less future refractory pain. This highlights insufficient effect of biologics in patients with inflammation-independent pain, warranting alternative treatments.

Disproportionate articular pain is a frequent phenomenon in rheumatoid arthritis and responds to treatment with sarilumab

OBJECTIVES

In some patients with RA, joint pain is more severe than expected based on the amount of joint swelling [referred to as disproportionate articular pain (DP)]. We assessed DP prevalence and the effects of sarilumab, an IL-6 inhibitor, on DP.

METHODS

Data from RA patients treated with placebo or 200 mg sarilumab in the phase 3 randomized controlled trials (RCTs) MOBILITY and TARGET, adalimumab 40 mg or sarilumab 200 mg in the phase 3 RCT MONARCH and sarilumab 200 mg in open-label extensions (OLEs) were used. DP was defined as an excess tender 28-joint count (TJC28) over swollen 28-joint count (SJC28) of ≥7 (TJC28 - SJC28 ≥ 7). Treatment response and disease activity were determined for patients with and without DP.

RESULTS

Of 1531 sarilumab 200 mg patients from RCTs, 353 (23%) had baseline DP. On average, patients with DP had higher 28-joint DAS using CRP (DAS28-CRP) and pain scores than patients without DP, whereas CRP levels were similar. After 12 and 24 weeks, patients with baseline DP treated with sarilumab were more likely to be DP-free than those treated with placebo or adalimumab. In RCTs, more sarilumab-treated patients achieved low disease activity vs comparators, regardless of baseline DP status. In OLEs, patients were more likely to lose rather than gain DP status.

CONCLUSION

About one-quarter of patients with RA experienced DP, which responded well to sarilumab. These data support the concept that other mechanisms (potentially mediated via IL-6) in addition to inflammation may contribute to DP in RA.

TRIAL REGISTRATIONS

NCT01061736, NCT02332590, NCT01709578, NCT01146652.

Trajectories of self-reported pain-related health outcomes and longitudinal effects on medication use in rheumatoid arthritis: a prospective cohort analysis using the Australian Rheumatology Association Database (ARAD)

OBJECTIVE

To determine distinct trajectories of self-reported pain-related health status in rheumatoid arthritis (RA), their relationship with sociodemographic factors and medication use.

METHODS

988 Australian Rheumatology Association Database participants with RA (71% female, mean age 54 years, mean disease duration 2.3 years) were included. Distinct multi-trajectories over 15-year follow-up for five different self-reported pain-related health outcome measures (Health Assessment Questionnaire Disability Index, visual analogue scores for pain, arthritis, global health and the Assessment of Quality of Life utility index) were identified using latent variable discrete mixture modelling. Random effects models were used to determine associations with medication use and biologic therapy modification during follow-up.

RESULTS

Four, approximately equally sized, pain/health status groups were identified, ranging from 'better' to 'poorer', within which changes over time were relatively small. Important determinants of those with poorer pain/health status included female gender, obesity, smoking, socioeconomic indicators and comorbidities. While biologic therapy use was similar between groups during follow-up, biologic therapy modifications (p_linear<0.001) and greater tendency of non-tumour necrosis factor inhibitor use (p_linear<0.001) were observed in those with poorer pain/health status. Similarly, greater use of opioids, prednisolone and non-steroidal anti-inflammatory drugs was seen in those with poorer pain/health status.

CONCLUSION

In the absence of disease activity information, distinct trajectories of varying pain/health status were seen from the outset and throughout the disease course in this RA cohort. More biologic therapy modifications and greater use in anti-inflammatories, opioids and prednisolone were seen in those with poorer pain/health status, reflecting undesirable lived experience of persistent pain in RA.

Using the derived 28-joint disease activity score patient-reported components (DAS28-P) index as a discriminatory measure of response to disease-modifying anti-rheumatic drug therapy in early rheumatoid arthritis

Background

The 28-joint disease activity score (DAS28) is a widely used measure to assess disease activity in rheumatoid arthritis (RA). The DAS28-P index, a derived proportion of the patient-reported components (joint tenderness and patient global assessment) within the DAS28, has been utilized as a discriminatory measure of non-inflammatory pain mechanisms in RA. This study aimed to evaluate the use of the DAS28-P index as a predictor of treatment response in early RA.

Methods

Patients with early RA enrolled in a supplemental fish oil clinical trial received a combination of disease-modifying anti-rheumatic drugs (DMARDs) according to a ‘treat-to-target’ protocol. First, consecutive measures of the DAS28-P index, derived from the DAS28-erythrocyte sedimentation rate (DAS28-ESR), at each visit over a 1-year period were estimated for each patient. Then, distinct subgroups of treatment responders based on the trajectories of the DAS28-P indices were identified using bivariate k-means cluster analysis. Data on baseline predictors as well as longitudinal outcomes of disease impact and DMARD use over a 1-year period and radiographic progression over a 3-year period were collected and analyzed using a random intercept, population-averaged generalized estimating equation model.

Results

121 patients were included (74% female; mean age of 57; median of 16 weeks of active disease) and a 3-cluster model was identified—the ‘Responders’ group (n = 58; 48%), the ‘Partial Responders’ group (n = 32; 26%), and the ‘Non-Responders’ group (n = 31; 26%). The ‘Partial Responders’ group had consistently higher proportions of the DAS28-P index throughout the study period and had minimal radiographic progression over time, with the lowest joint erosion score of 0.9 [95% confidence interval (CI) 0.2, 1.6], observed at the 3-year follow-up. At 52 weeks, the methotrexate dose was higher for both ‘Partial Responders’ and ‘Non-Responders’ groups (18.5 mg [95% CI 15.5, 21.5] and 18.6 mg [95% CI 15.3, 21.8] respectively), when compared with the ‘Responders’ group (12.8 mg [95% CI 14.7, 20.9]).

Conclusions

Persistently high DAS28-P index scores are useful to distinguish poor patient global assessment and excessive treatment escalation in early RA, suggestive of underlying non-inflammatory pain contributing to higher disease activity score. Early identification of patients with discordant subjective and objective components of composite disease activity measures may allow better tailoring of treatment in RA.

Predictive model to identify multiple failure to biological therapy in patients with rheumatoid arthritis

Background:

Despite advances in the treatment of rheumatoid arthritis (RA) and the wide range of therapies available, there is a percentage of patients whose treatment presents a challenge for clinicians due to lack of response to multiple biologic and target-specific disease-modifying antirheumatic drugs (b/tsDMARDs).

Objective:

To develop and validate an algorithm to predict multiple failure to biological therapy in patients with RA.

Design:

Observational retrospective study involving subjects from a cohort of patients with RA receiving b/tsDMARDs.

Methods:

Based on the number of prior failures to b/tsDMARDs, patients were classified as either multi-refractory (MR) or non-refractory (NR). Patient characteristics were considered in the statistical analysis to design the predictive model, selecting those variables with a predictive capability. A decision algorithm known as ‘classification and regression tree’ (CART) was developed to create a prediction model of multi-drug resistance. Performance of the prediction algorithm was evaluated in an external independent cohort using area under the curve (AUC).

Results:

A total of 136 patients were included: 51 MR and 85 NR. The CART model was able to predict multiple failures to b/tsDMARDs using disease activity score-28 (DAS-28) values at 6 months after the start time of the initial b/tsDMARD, as well as DAS-28 improvement in the first 6 months and baseline DAS-28. The CART model showed a capability to correctly classify 94.1% NR and 87.5% MR patients with a sensitivity = 0.88, a specificity = 0.94, and an AUC = 0.89 (95% CI: 0.74–1.00). In the external validation cohort, 35 MR and 47 NR patients were included. The AUC value for the CART model in this cohort was 0.82 (95% CI: 0.73–0.9).

Conclusion:

Our model correctly classified NR and MR patients based on simple measurements available in routine clinical practice, which provides the possibility to characterize and individualize patient treatments during early stages.

Defining the relationship between pain intensity and disease activity in patients with rheumatoid arthritis: a secondary analysis of six studies

Background

Pain is the main concern of patients with rheumatoid arthritis (RA) while reducing disease activity dominates specialist management. Disease activity assessments like the disease activity score for 28 joints with the erythrocyte sedimentation rate (DAS28-ESR) omit pain creating an apparent paradox between patients’ concerns and specialists’ treatment goals. We evaluated the relationship of pain intensity and disease activity in RA with three aims: defining associations between pain intensity and disease activity and its components, evaluating discordance between pain intensity and disease activity, and assessing temporal changes in pain intensity and disease activity.

Methods

We undertook secondary analyses of five trials and one observational study of RA patients followed for 12 months. The patients had early and established active disease or sustained low disease activity or remission. Pain was measured using 100-mm visual analogue scales. Individual patient data was pooled across all studies and by types of patients (early active, established active and established remission). Associations of pain intensity and disease activity were evaluated by correlations (Spearman’s), linear regression methods and Bland-Altman plots. Discordance was assessed by Kappa statistics (for patients grouped into high and low pain intensity and disease activity). Temporal changes were assessed 6 monthly in different patient groups.

Results

A total of 1132 patients were studied: 490 had early active RA, 469 had established active RA and 173 were in remission/low disease activity. Our analyses showed, firstly, that pain intensity is associated with disease activity in general, and particularly with patient global assessments, across all patient groups. Patient global assessments were a reasonable proxy for pain intensity. Secondly, there was some discordance between pain intensity and disease activity across all disease activity levels, reflecting similar discrepancies in patient global assessments. Thirdly, there were strong temporal relationships between changes in disease activity and pain intensity. When mean disease activity fell, mean pain intensity scores also fell; when mean disease activity increased, there were comparable increases in pain intensity.

Conclusions

These findings show pain intensity is an integral part of disease activity, though it is not measured directly in DAS28-ESR. Reducing disease activity is crucial for reducing pain intensity in RA.

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.

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.

Contribution of P2X4 receptor in pain associated with rheumatoid arthritis: a review

Pain is the most common symptom reported by patients with rheumatoid arthritis (RA) even after the resolution of chronic joint inflammation. It is believed that RA-associated pain is not solely due to inflammation, but could also be attributed to aberrant modifications to the central nervous system. The P2X4 receptor (P2X4R) is an ATP-activated purinergic receptor that plays a significant role in the transmission of information in the nervous system and pain. The involvement of P2X4R during the pathogenesis of chronic inflammatory pain and neuropathic pain is well-established. The attenuation of this receptor alleviates disease pathogenesis and related symptoms, including hyperalgesia and allodynia. Although some studies have revealed the contribution of P2X4R in promoting joint inflammation in RA, how it implicates pain associated with RA at peripheral and central nervous systems is still lacking. In this review, the possible contributions of P2X4R in the nervous system and how it implicates pain transmission and responses were examined.

The association between increased body mass index and response to conventional synthetic DMARD treatment in rheumatoid arthritis: Results from the METEOR database

BACKGROUND

Few data exist on the association between increased BMI and response to conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) in rheumatoid arthritis (RA).We aimed to explore the association between increased (overweight or obese) BMI on csDMARD-prescribing, methotrexate-dose and disease activity over 12-months.

METHODS

Participants in an international RA database were stratified into early (<1year post-diagnosis) and established RA. EULAR response, DAS28 remission and treatments were recorded at baseline, 6-months and 12-months. Increased BMI was explored in early and established RA, as predictors of good EULAR response, DAS28 remission, number of csDMARDs and methotrexate-dose, using logistic and linear regression.

RESULTS

Data from 1313 patients, 44.3% with early RA, were examined. In early RA, increased BMI was not significantly associated with remission. In established RA, obese patients on monotherapy were significantly less likely to achieve good EULAR response or DAS28 remission at 6 months and more likely to be treated with combination csDMARDs, compared with normal BMI. In patients taking methotrexate, overweight and obese patients with early and established RA were exposed to higher methotrexate doses (mono- and combination-therapy), with a mean dose of 20mg/week, compared to 15mg/week in those of normal BMI.

CONCLUSION

We observed, compared to patients with normal BMI, overweight and obese individuals experienced more intensive csDMARD exposures. Similar response rates were observed in early RA but increased BMI was associated with reduced response in established RA. Optimisation of targeted RA treatment remains important, particularly in those with increased BMI where response in established disease may be attenuated.

Why It Hurts: The Mechanisms of Pain in Rheumatoid Arthritis

Pain is a near-universal feature of rheumatoid arthritis, but peripheral joint inflammation may not suffice to explain the etiology of pain in all patients with rheumatoid arthritis. Inflammation in rheumatoid arthritis releases several algogens that may generate pain. Also, central nervous system processes may play a crucial role in the regulation and perpetuation of pain. Several methods for assessing pain in rheumatoid arthritis exist, and recently the role of assessing therapeutics in treating specific etiologies of pain has gained interest.

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.

Association of body composition with disease activity and disability in rheumatoid arthritis

BACKGROUND/AIMS

To explore the associations between body composition and pain, disease activity, and disability in rheumatoid arthritis (RA).

METHODS

The study enrolled 335 patients with RA and underwent body composition measurement with an InBody analyzer. The associations of body mass index (BMI), body fat mass, and skeletal muscle mass with disease activity score in 28 joints (DAS28), an index derived to measure the subjective component of DAS28 (DAS28-P), a pain visual analogue scale (VAS), and disability measured with the health assessment questionnaire (HAQ) were explored. Obesity was defined as BMI ≥ 25 kg/m2.

RESULTS

The median (interquartile range) disease duration was 6 years (3.5 to 9) and the mean DAS28 score was 3.6 ± 1.1. The mean BMI was 23.6 ± 3.6 kg/m2 and 109 patients (32.5%) were obese. Compared with non-obese patients, obese patients had a higher C-reactive protein (1.68 mg/dL vs. < 0.1 mg/dL, p = 0.013), higher pain VAS score (40 vs. 35, p = 0.031), and higher DAS28-erythrocyte sedimentation rate score (3.75 ± 1.18 vs. 3.46 ± 1.11, p = 0.031). In multivariate regression analysis, the DAS28 score in females was positively associated with the current steroid dose, body fat mass, and HAQ score, while the HAQ score in females was associated with older age, DAS28, lower skeletal muscle mass, and higher body fat/skeletal muscle ratio. In the multivariate regression analysis, the DAS28-P score in females was positively associated with body fat/skeletal muscle ratio and HAQ.

CONCLUSION

Body composition, such as the body fat mass and body fat/skeletal muscle ratio, is significantly associated with disease activity and disability in female RA patients.

The neuropathic phenotype of the K/BxN transgenic mouse with spontaneous arthritis: pain, nerve sprouting and joint remodeling

The adult K/BxN transgenic mouse develops spontaneous autoimmune arthritis with joint remodeling and profound bone loss. We report that both males and females display a severe sustained tactile allodynia which is reduced by gabapentin but not the potent cyclooxygenase inhibitor ketorolac. In dorsal horn, males and females show increased GFAP⁺ astrocytic cells; however, only males demonstrate an increase in Iba1⁺ microglia. In dorsal root ganglia (DRG), there is an increase in CGRP⁺, TH⁺, and Iba1⁺ (macrophage) labeling, but no increase in ATF3⁺ cells. At the ankle there is increased CGRP⁺, TH⁺, and GAP-43⁺ fiber synovial innervation. Thus, based on the changes in dorsal horn, DRG and peripheral innervation, we suggest that the adult K/BxN transgenic arthritic mice display a neuropathic phenotype, an assertion consistent with the analgesic pharmacology seen in this animal. These results indicate the relevance of this model to our understanding of the nociceptive processing which underlies the chronic pain state that evolves secondary to persistent joint inflammation.

High Proportion of Subjective Component to the Disease Activity Score is Associated with Favorable Response to Abatacept in Rheumatoid Arthritis

BACKGROUND

Response prediction of certain biologic agents for the treatment of rheumatoid arthritis (RA) remains an unmet need in real-world clinical practice. The contribution of patient-reported components to the 28-joint Disease Activity Score (DAS28) was termed DAS28-P and investigated as a predictor of response to biologic agents, mostly tumor necrosis factor inhibitors. We aimed to evaluate DAS28-P as a predictor of the European League Against Rheumatism (EULAR) response to abatacept in patients with RA.

METHODS

The study population was a prospective, observational, multicenter cohort of Korean patients with RA, who were followed up for a nationwide post-marketing surveillance study of abatacept. Correlation of DAS28-P with DAS28, change of DAS28, and EULAR response groups were evaluated. Logistic regression analysis was used to predict good-to-moderate EULAR response to abatacept in the study population.

RESULTS

A total of 341 patients were involved in the analysis stratified on the EULAR response criteria. Presence of comorbidities, previous exposure to biologic agents, baseline DAS28, three of its components (tender joint counts, global health visual analog scale, erythrocyte sedimentation rate), and baseline DAS28-P were significantly associated with EULAR response to abatacept at 6 months. Stratified upon EULAR response, a group with good-to-moderate response had a higher baseline value and lower interval change for DAS28-P. Logistic regression analysis showed that a DAS28-P cut-off of > 0.44 was more positively associated with good-to-moderate EULAR response with abatacept treatment than naivety to biologic agents.

CONCLUSIONS

The DAS28-P could be predictive of response to abatacept. A higher baseline DAS28-P is associated with a favorable therapeutic response to abatacept.

TRIAL REGISTRATION

Trial name, Korean Post-marketing Surveillance for Orencia^®. Trial registration number, NCT01583244. Registered on April 20, 2012.

A Review on Chronic Pain in Rheumatoid Arthritis: A Focus on Activation of NR2B Subunit of N-Methyl-D-Aspartate Receptors

Chronic pain is a debilitating condition that occurs after tissue damage, which substantially affects the patient's emotional state and physical activity. The chronic pain in rheumatoid arthritis (RA) is the result of various autoimmune-induced inflammatory reactions in the joints. Both types of peripheral and central pain processing can lead to sensitisation. Non-steroidal anti-inflammatory drugs (NSAIDs) and disease-modifying anti-rheumatic drugs (DMARDs) can result in potent anti-inflammatory effect. However, these drugs are not able to suppress the pain from RA for a prolonged period. For years, researchers have examined the role of the N-methyl-D-aspartic acid receptor 2B (NR2B) subunit of N-methyl-D-aspartate receptors (NMDAR) in chronic and neuropathic pain models. This NMDAR subtype can be found in at the peripheral and central nervous system and it represents an effective therapy for RA pain management. This review focuses on the NR2B subunit of NMDAR and the different pathways leading to its activation. Furthermore, specific attention is given to the possible involvement of NR2B subunit in the peripheral and central pathogenesis of RA.

Disease activity flares and pain flares in an early rheumatoid arthritis inception cohort; characteristics, antecedents and sequelae

Background

RA flares are common and disabling. They are described in terms of worsening inflammation but pain and inflammation are often discordant. To inform treatment decisions, we investigated whether inflammatory and pain flares are discrete entities.

Methods

People from the Early RA Network (ERAN) cohort were assessed annually up to 11 years after presentation (n = 719, 3703 person-years of follow up). Flare events were defined in 2 different ways that were analysed in parallel; DAS28 or Pain Flares. DAS28 Flares satisfied OMERACT flare criteria of increases in DAS28 since the previous assessment (≥1.2 points if active RA or ≥ 0.6 points if inactive RA). A ≥ 4.8-point worsening of SF36-Bodily Pain score defined Pain Flares. The first documented episode of each of DAS28 and Pain Flare in each person was analysed. Subgroups within DAS28 and Pain Flares were determined using Latent Class Analysis. Clinical course was compared between flare subgroups.

Results

DAS28 (45%) and Pain Flares (52%) were each common but usually discordant, with 60% of participants in DAS28 Flare not concurrently in Pain Flare, and 64% of those in Pain Flare not concurrently in DAS28 Flare. Three discrete DAS28 Flare subgroups were identified. One was characterised by increases in tender/swollen joint counts (14.4%), a second by increases in symptoms (13.1%), and a third displayed lower flare severity (72.5%). Two discrete Pain Flare subgroups were identified. One occurred following low disease activity and symptoms (88.6%), and the other occurred on the background of ongoing active disease and pain (11.4%). Despite the observed differences between DAS28 and Pain Flares, each was associated with increased disability which persisted beyond the flare episode.

Conclusion

Flares are both common and heterogeneous in people with RA. Furthermore our findings indicate that for some patients there is a discordance between inflammation and pain in flare events. This discrete flare subgroups might reflect different underlying inflammation and pain mechanisms. Treatments addressing different mechanisms might be required to reduce persistent disability after DAS28 and Pain Flares.

The Effect of Neuropathic Pain Symptoms on Remission in Patients with Early Rheumatoid Arthritis

BACKGROUND

The presence of neuropatic pain (NeP) is common in subjects with established Rheumatoid Arthritis (RA), and it can influence the disease remission. These aspects have not been investigated in patients with Early Rheumatoid Arthritis (ERA).

OBJECTIVE

To investigate the effect of NeP on the achievement of remission in patients with ERA.

METHOD

The study involved consecutive ERA patients with moderate or high disease activity. The painDETECT Questionnaire (PDQ), the 36-item Short Form Health Survey (SF-36), and the Euro- QoL-5 Dimensions (EQ-5D) were administered to all the patients, and their co-morbidity data were used to calculate their modified Rheumatic Disease Comorbidity Index (mRDCI). After six months' follow-up, the presence or otherwise of NeP in each individual patient was calculated, and whether or not the Boolean remission criteria were satisfied.

RESULTS

The study was completed by 115 patients (76% females) whose PDQ scores indicated that 13% had probable NeP. At the end of the follow-up period, 25 patients (21.7%) met the Boolean remission criteria. Logistic regression analysis showed that baseline PDQ scores (p=0.0023) and the mRDCI (p=0.0054) were the strongest predictors of not being in Boolean remission. Only one of the 15 patients with concomitant NeP achieved Boolean remission.

CONCLUSION

The presence of NeP may affect the achievement of remission in ERA patients. The PDQ can be a useful tool to measure central pain sensitisation in such patients.

[Chronic pain and depression in patients with rheumatoid arthritis: results of five - year follow - up]

The aim of the study was to analyze the factors affecting chronic pain in patients with rheumatoid arthritis (RA).

MATERIALS AND METHODS

128 patients with reliable diagnosis of RA [111 (86.7%) women and 17 (13.3%) men] were examined. The mean age of patients was 47.4±11.3 years, the median duration of the disease was 96 [48; 228] months. When included in the study in most patients, the activity of RA in DAS28 was moderate (n=56; 43.7%) or high (n=48; 37.5%). BPI (Brief Pain Inventory) scale was used to determine the severity of pain and its impact on various aspects of life. The anxiety - depressive spectrum disorders (ADDs) were diagnosed by psychiatrist during a semistructured interview according to ICD-10 criteria in 123 (96.1%) patients. The severity of depression was determined by the Montgomery-Asberg depression rating scale, anxiety - by Hamilton anxiety scale. For the diagnosis of cognitive impairment used clinical and psychological techniques. Psychopharmacotherapy (PPhT) by antidepressants or anxiolytics is offered to all patients with ADDs, 52 of them agreed to treatment, 71 patients refused. The next groups selected depending on the therapy: 1st - with conventional disease - modifying antirheumatic drugs (cDMARDs; n=39), 2nd - with cDMARDs+PPhT (n=43), 3d - with cDMARDs + biologic (b) DMARDs (n=32), 4th - with cDMARD+bDMARDs+PPhT (n=9). The dynamics of ADDs and outcomes of RA in 5 years were evaluated in 83 (67.5%) patients.

RESULTS

When included in the study, 94 (75.2%) patients with RA had moderate and severe pain. According to the regression analysis, the maximum intensity pain in BPImax after 5 years of follow - up associated not the only factors connected with RA - high DAS28, the serum level of C-reactive protein, the degree of radiological stage and functional insufficiency, duration of RA and a lesser duration of glucocorticoids intake, but also with continuing depressive episodes in the framework of recurrent depression and the initial presence of cognitive impairment. The severity of pain after 5 years of follow - up was higher in RA patients receiving only сDMARDs, without the use of bDMARDs and in the absence of PPhT associated with ADDs.

CONCLUSION

Depressive episode within recurrent major depression is a significant factor in the chronicity of pain in patients with RA. Timely effective PPhT of depression, selected taking into account depression structure and personal characteristics of the patient, leads to a steady decrease in the severity of pain in patients with RA.

Validity of a two-component imaging-derived disease activity score for improved assessment of synovitis in early rheumatoid arthritis

OBJECTIVES

Imaging of joint inflammation provides a standard against which to derive an updated DAS for RA. Our objectives were to develop and validate a DAS based on reweighting the DAS28 components to maximize association with US-assessed synovitis.

METHODS

Early RA patients from two observational cohorts (n = 434 and n = 117) and a clinical trial (n = 59) were assessed at intervals up to 104 weeks from baseline; all US scans were within 1 week of clinical exam. There were 899, 163 and 183 visits in each cohort. Associations of combined US grey scale and power Doppler scores (GSPD) with 28 tender joint count and 28 swollen joint count (SJC28), CRP, ESR and general health visual analogue scale were examined in linear mixed model regressions. Cross-validation evaluated model predictive ability. Coefficients learned from training data defined a re-weighted DAS28 that was validated against radiographic progression in independent data (3037 observations; 717 patients).

RESULTS

Of the conventional DAS28 components only SJC28 and CRP were associated with GSPD in all three development cohorts. A two-component model including SJC28 and CRP outperformed a four-component model (R2 = 0.235, 0.392, 0.380 vs 0.232, 0.380, 0.375, respectively). The re-weighted two-component DAS28CRP outperformed conventional DAS28 definitions in predicting GSPD (Δtest log-likelihood <-2.6, P < 0.01), Larsen score and presence of erosions.

CONCLUSION

A score based on SJC28 and CRP alone demonstrated stronger associations with synovitis and radiographic progression than the original DAS28 and should be considered in research on pathophysiological manifestations of early RA. Implications for clinical management of RA remain to be established.

Pain and affective distress in arthritis: relationship to immunity and inflammation

INTRODUCTION

Most arthritides are associated with pain and psychological distress (clinically significant depression and anxiety). Pain and depression are mutually exacerbating; both may continue even when joint involvement appears well controlled. Area covered: There is strong evidence that arthritis-related stress impacts the central nervous system and, together with peripheral inflammatory changes, can cause central sensitization that can lead to chronic pain and worsening of affective distress. Cytokines and chemokines participate both in joint inflammation and in central sensitization. We review evidence of these relationships in five arthritides, namely rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, gout, and in osteoarthritis of the hips and knees. Central sensitization in these conditions results in long-lasting pain and psychological distress. Expert commentary: Chronic pain and depression are important but often neglected in the clinical assessment and treatment of arthritis. The potential role of biologic cytokines and Janus kinase inhibitors in dealing with these symptoms needs further study.

Neuraxial TNF and IFN-beta co-modulate persistent allodynia in arthritic mice

In rheumatoid arthritis, joint pain can persist despite resolution of swelling. Similarly, in the murine K/BxN serum transfer model, a persistent tactile allodynia is observed after the resolution of joint inflammation (post-inflammatory pain) in male mice. Here, we found female wild type (WT) mice show inflammatory, but reduced post-inflammatory tactile allodynia. The transition to the post-inflammatory phenotype is dependent on TLR4 signaling. At the spinal level, we found differences in TNF and IFNβ mRNA expression in WT and TLR4 deficient males. In wild type male and female mice, there is differential temporal spinal expression of TNF and IFNβ. In WT males, blockade of TNF or administration of IFNβ was insufficient to affect the persistent allodynia. However, co-administration of intrathecal (IT) IFNβ and anti-TNF antibodies in male WT mice permanently reversed tactile allodynia. IT IFNβ treatment induces expression of anti-inflammatory proteins, contributing to the beneficial effect. Together, these experiments illustrated differences in the transition to chronic tactile allodynia in male and female animals and the complexities of effective pharmacologic interventions.

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

Rheumatoid arthritis (RA) is an example of human chronic inflammatory pain. Modern treatments suppress inflammation, yet pain remains a major problem for many people with RA. We hypothesized that discrete RA subgroups might display favorable or unfavorable pain trajectories when receiving treatment, and that baseline characteristics will predict trajectory allocation. Growth mixture modelling was used to identify discrete trajectories of Short Form-36 bodily pain scores during 3 years in 3 RA cohorts (Early RA Network (n = 683), British Society for Rheumatology Biologics Register Biologics (n = 7,090) and nonbiologics (n = 1,720) cohorts. Logistic regression compared baseline predictor variables between trajectories. The role of inflammation was examined in a subgroup analysis of people with normal levels of inflammatory markers after 3 years. The mean Short Form-36 bodily pain scores in each cohort improved but remained throughout 3 years of follow-up of >1 standard deviation worse than the UK general population average. Discrete persistent pain (59-79% of cohort participants) and resolving pain (19-27%) trajectories were identified in each cohort. In Early RA Network, a third trajectory displaying persistently low pain (23%) was also identified. In people with normal levels of inflammatory markers after 3 years, 65% were found to follow a persistent pain trajectory. When trajectories were compared, greater disability (adjusted odds ratio = 2.3-2.5 per unit baseline Health Assessment Questionnaire score) and smoking history (adjusted odds ratio = 1.6-1.8) were risk factors for persistent pain trajectories in each cohort. In conclusion, distinct trajectories indicate patient subgroups with very different pain prognosis during treatment for RA. Inflammation does not fully explain the pain trajectories, and noninflammatory factors as well as acute phase response predict which trajectory an individual will follow. Targeted treatments additional to those which suppress inflammation might reduce the long-term burden of arthritis pain. PERSPECTIVE: Immunosuppression decreases inflammation in RA, but pain outcomes are less favorable. Discrete persistent and resolving pain trajectories were identified after treatment, both in early and established RA. Smoking and greater disability at baseline predicted persistent pain. Identifying patient subgroups with a poor pain prognosis could enable adjunctive treatment to improve outcomes.

Is a Fundamental Change in the Interpretation of Rheumatoid Arthritis Disease Activity Necessary?

Disease Activity Score (DAS) composite models are moderately precise and robust measures of disease severity when they are used in rheumatoid arthritis (RA) cohorts. They are less so when used for individual patients. This is because subjective components, patient global assessment of well-being and tender joint count, modified by factors other than RA biological disease activity, often obfuscate interpretation of disease activity. Comorbidities, especially distress, can disproportionately inflate these components. Fibromyalgia, essentially synonymous with distress, pain augmentation, and depression, is a common comorbidity. Its presence and severity can be determined by the Polysymptomatic Distress Scale (PSD). The differential effects of distress and fibromyalgia syndrome on the DAS can be demonstrated by manipulating information already there: the arithmetic differences or ratios of the tender joint count and swollen joint count and comparison of the modified disease activity score with 28 joints to the disease activity score with 28 joints-patient (DAS28-derived indices that measure the contribution of the relatively objective or relatively subjective components, respectively). The potentially more objective multibiomarker disease activity might also be used to test the severity of biological RA disease activity. These tools may be used to elucidate disproportionate values for subjective DAS model components, which then should facilitate identification of the underlying process factors, including depression, for potential treatment.

Mansoa alliacea extract presents antinociceptive effect in a chronic inflammatory pain model in mice through opioid mechanisms

In some chronic disorders, as in arthritis, the inflammatory pain persists beyond the inflammation control becoming pathological. Its treatment shows limited efficacy and adverse effects which compromises patients' quality of life. Mansoa alliacea, known as 'cipo alho', is popularly used as analgesic and others species of this genus show anti-inflammatory actions. We investigated the anti-inflammatory and antinociceptive potential of M. alliacea extract in an inflammatory pain model which presents inflammatory characteristics similar to those caused by arthritis, through of the intraplantar injection of complete Freund's adjuvant (CFA) in mice. The extract chromatographic analysis revealed the presence of ρ-coumaric, ferulic and chlorogenic acids, luteolin, and apigenin. The treatment with M. alliacea prevented and reversed the CFA-induced mechanical allodynia with maximum inhibition (I_max) of 100% and 90 ± 10%, respectively. The co-administration of M. alliacea extract plus morphine enhanced the anti-allodynic effect with I_max of 100%. The M. alliacea extract also reverted the CFA-induced thermal hyperalgesia with I_max of 3.6 times greater compared to the vehicle and reduced the thermal threshold under physiological conditions. However, M. alliacea extract did not reduce the CFA-induced edema and myeloperoxidase activity. Additionally, non-selective and δ-selective opioid receptor antagonists, but not κ-opioid, prevented extract anti-allodynic effect with I_max of 98 ± 2% and 93 ± 2%, respectively. Moreover, M. alliacea extract did not induce adverse effects commonly caused by opioids and other analgesic drugs, at least in the tested pharmacological doses after the acute treatment. M. alliacea extract presents antinociceptive activity in an inflammatory pain model, which presents inflammatory characteristics similar to those arthritis-induced, without causing adverse effects in tested pharmacological doses. These effects seem to be mediated mainly via δ-opioid receptors.

Mechanisms for Joint Pain in Rheumatoid Arthritis (RA): from Cytokines to Central Sensitization

PURPOSE OF REVIEW

Pain in rheumatoid arthritis (RA) may be due to different etiologies, ranging from peripheral inflammation to dysregulation of central nervous system (CNS) processing. This review evaluates relevant literature published on RA pain mechanisms in recent years.

RECENT FINDINGS

Despite successes of disease-modifying antirheumatic drugs (DMARDs), pain persists for many RA patients. Studies involving patient-reported outcomes, quantitative sensory testing, and neuroimaging indicate that, in addition to joint inflammation, abnormalities in CNS pain processing may contribute to pain. Some DMARDs (e.g., janus kinus inhibitors) may work via multiple pathways to decrease pain. Adjunctive treatments (e.g., antidepressants, antiepileptics) may also be useful in managing pain in RA patients with well-controlled disease. Both peripheral and central mechanisms play key roles in the expression of pain in RA. To effectively manage pain, physicians need accurate assessment tools to identify the pathways involved in each patient so that treatments may be appropriately targeted.

MicroRNA‑143‑3p contributes to the regulation of pain responses in collagen‑induced arthritis

Patients with rheumatoid arthritis (RA) suffer from pain, which is associated with inflammation, peripheral and central pain processing, and joint structure damage. The aim of the present study was to investigate a key microRNA (miR) and its target genes that are involved in the pain responses of RA, and to clarify the mechanism of pain regulation. Collagen‑induced arthritis (CIA) was induced in DBA/1 and C57BL/6 mice. The paw swelling, mechanical withdrawal threshold (MWT), thermal withdrawal latency (TWL), and expression levels of tumor necrosis factor (TNF)‑α and prostaglandin (PG)E2 in the sera were investigated. Decreased MWT and TWL, and increased TNF‑α and PGE2, in the CIA model group were observed in DBA/1 and C57BL/6 mice. DBA/1 mice exhibited greater hyperalgesia and higher levels of inflammatory mediators. miR‑143‑3p expression in the blood and the dorsal root ganglion (DRG) were detected, and low miR‑143‑3p expression was demonstrated in the blood and DRG tissue of CIA mice. The target genes of miR‑143 were predicted and analyzed. A total of 1,305 genes were predicted and 55 pain‑associated genes were obtained. Prostaglandin‑endoperoxide synthase 2 (Ptgs2), MAS related GPR family member E (Mrgpre), prostaglandin D2 receptor and Tnf were selected as target genes of miR‑143. DRG cells were cultured and transfected with miR‑143‑3p inhibitor or mimic. The expression of Mrgpre, Ptgs2 and Tnf was significantly inhibited following miR‑143‑3p mimic transfection, while the expression of Mrgpre, Ptgs2 and Tnf was increased following inhibitor transfection. Additionally, the expression of pain‑associated genes in the DRG of mice was investigated and the expression of Ptgs2, Mrgpre and Tnf in the DRG of CIA mice was also significantly upregulated. These results revealed that CIA mice exhibited marked hyperalgesia and high levels of inflammatory pain mediators. Low expression of miR‑143‑3p negatively regulated the pain‑associated target genes, including Mrgpre, Ptgs2 and Tnf, thereby affecting chronic inflammatory pain and neuropathic pain in RA.

Inflammation, obesity and rheumatic disease: common mechanistic links. A narrative review

Obesity represents a rising global health concern, linked to significant social, psychological and physical burden to the individual affected, people around them and the society as a whole. Obesity has been described as a low-grade inflammatory condition, associated with increased production of pro-inflammatory mediators like tumor necrosis factor alpha or interleukin 6 and altered expression of adipokines. Adipokines, mainly produced by adipose tissue, have mixed pro- and anti-inflammatory properties. Obesity rarely exists on its own; instead, it tends to coexist with (often multiple) other comorbidities, including metabolic, cardiovascular, and rheumatic and musculoskeletal diseases (RMDs). In the case of RMDs, evidence is rapidly accumulating on common mechanistic pathways implicated in the inflammatory states seen between RMDs and obesity. Although there remain unanswered questions on the exact mechanisms of inflammation that link obesity to RMDs, what is becoming increasingly known is the association between obesity and adverse clinical outcomes in RMDs. This narrative review discusses insights into mechanisms of inflammation linking obesity and RMDs and evidence on the impact of obesity on treatment response and important disease outcomes. We highlight the importance of targeting obesity, a common and modifiable comorbidity, as part of the routine care of people with RMDs.

High prevalence of widespread pain in women with early rheumatoid arthritis

OBJECTIVES

The aim of the study was to determine the prevalence of widespread pain (WP) in women with early rheumatoid arthritis (RA) and to compare physical function, activity limitations, health-related quality of life, mental distress, and disease activity between women with WP and non-widespread pain (NWP).

METHOD

This cross-sectional study included 102 women with early RA. Participants were provided with self-reported questionnaires quantifying activity limitations, physical activity, pain intensity, health-related quality of life, and fatigue. Hand-grip force, muscle function test of the lower extremities, erythrocyte sedimentation rate, and number of tender and swollen joints were assessed.

RESULTS

One-third (35.9%) of the women fulfilled the American College of Rheumatology criteria for WP 20 months after disease onset. Women with RA + WP had significantly higher 28-joint Disease Activity Score (DAS28) (p = 0.004), number of tender joints (p = 0.001), pain intensity (p < 0.001), fatigue (p < 0.001), Health Assessment Questionnaire score (p < 0.001), and Hospital Anxiety and Depression Scale - Depression (p = 0.001). Furthermore, women with RA + WP showed significantly worse global health (p < 0.001) and physical health (36-item Short Form Health Survey - Physical Component Summary) (p < 0.001). The hand-grip force was found to be significantly reduced (p = 0.001), as was the muscle function of the lower extremities (p < 0.001), for women with RA + WP compared to women with RA + NWP. After adjustment for inflammatory joint disease, the significant differences between the groups remained.

CONCLUSION

A significant group of women with early RA experience WP with a high DAS28 and increased pain intensity level. These women display severe muscle function deficiency in clinical examinations, and report general activity limitations and low psychological and physical health, despite an absence of or low objective signs of inflammation.

The subjective components of the Disease Activity Score 28-joints (DAS28) in rheumatoid arthritis patients and coexisting fibromyalgia

To determine the contribution of fibromyalgia (FM) to the subjective components of the Disease Activity Score 28-joints (DAS28) in patients with rheumatoid arthritis (RA), and to analyse the discriminatory performance of the derived DAS28 patient-reported components (DAS28-P) to identify patients with fibromyalgic RA. Consecutive RA patients underwent clinical and clinimetric assessment. The DAS28-P index was derived from the components of the DAS28 scores by rearranging the DAS28-ESR formula. Patients were distinguished by the presence of FM. Student parametric t tests or Mann-Whitney non-parametric U tests were used to determine any between-group differences. Receiver operating characteristic (ROC) curve analysis was used to test the ability of the DAS28-P index to distinguish patients with RA and those with fibromyalgic RA. The study involved 292 RA patients (80.5% females, mean age 63 years) with a mean disease duration of 11.6 ± 8.5 years. Forty-three patients (14.7%) had concomitant FM, and significantly higher tender joint count (p < 0.001), pain numerical rating scale, global health status (p = 0.007), and DAS28 scores (p = 0.006) than those without FM. The DAS28-P values were also significantly higher in the patients with FM (0.68 ± 0.09 vs 0.58 ± 0.06; p < 0.001). The discriminatory power of the DAS28-P was very good (area under the ROC of 0.858, optimal cut-off value of 0.631). The presence of FM strongly influences the DAS28 results. The assessment of patient-reported components to the DAS28 through the DAS28-P can be a useful way to identify patients with fibromyalgic RA.

The association of obesity with disease activity, functional ability and quality of life in early rheumatoid arthritis: data from the Early Rheumatoid Arthritis Study/Early Rheumatoid Arthritis Network UK prospective cohorts

OBJECTIVES

To examine associations between BMI and disease activity, functional ability and quality of life in RA.

METHODS

Data from two consecutive, similarly designed UK multicentre RA inception cohorts were used: the Early RA Study (ERAS) and the Early RA Network (ERAN). Recruitment figures/median follow-up for the ERAS and ERAN were 1465/10 years (maximum 25 years), and 1236/6 years (maximum 10 years), respectively. Standard demographic and clinical variables were recorded at baseline and annually. Multilevel piecewise longitudinal models with a change point at 2 years were used with the 28-joint DAS (DAS28), ESR, HAQ and 36-item Short Form Health Survey (SF-36) physical (PCS) and mental (MCS) components as dependent variables. BMI was examined in separate models as both continuous and categorical variables (based on World Health Organization definitions) and up to 5 years from disease onset.

RESULTS

BMI data from 2386 newly diagnosed RA patients (11 348 measures) showed an increase in BMI of 0.27 U annually (95% CI 0.21, 0.33). Baseline obesity was associated with a significant reduction in the odds of achieving a low year 2 DAS28 [OR 0.52 (95% CI 0.41, 0.650)]. At year 2, HAQ and SF-36 PCS scores were significantly worse but not at year 5 in patients obese at baseline. Obesity at year 2 was associated with higher DAS28 scores at year 2, but not at year 5, and also associated with significantly higher HAQ and SF-36 PCS scores at years 2 and 5.

CONCLUSION

Obesity prevalence is rising in early RA and associates with worse disease activity, function and health-related quality of life, with a significant negative impact on achieving a low DAS28. The data argue strongly for obesity management to become central to treatment strategies in RA.

Tackling Pain Associated with Rheumatoid Arthritis: Proton-Sensing Receptors

Rheumatoid arthritis (RA), characterized by chronic inflammation of synovial joints, is often associated with ongoing pain and increased pain sensitivity. Chronic pain that comes with RA turns independent, essentially becoming its own disease. It could partly explain that a significant number (50%) of RA patients fail to respond to current RA therapies that focus mainly on suppression of joint inflammation. The acute phase of pain seems to associate with joint inflammation in early RA. In established RA, the chronic phase of pain could be linked to inflammatory components of neuron-immune interactions and noninflammatory components. Accumulating evidence suggests that the initial inflammation and autoimmunity in RA (preclinical RA) begin outside of the joint and may originate at mucosal sites and alterations in the composition of microbiota located at mucosal sites could be essential for mucosal inflammation, triggering joint inflammation. Fibroblast-like synoviocytes in the inflamed joint respond to cytokines to release acidic components, lowering pH in synovial fluid. Extracellular proton binds to proton-sensing ion channels, and G-protein-coupled receptors in joint nociceptive fibers may contribute to sensory transduction and release of neurotransmitters, leading to pain and hyperalgesia. Activation of peripheral sensory neurons or nociceptors further modulates inflammation, resulting in neuroinflammation or neurogenic inflammation. Peripheral and central nerves work with non-neuronal cells (such as immune cells, glial cells) in concert to contribute to the chronic phase of RA-associated pain. This review will discuss actions of proton-sensing receptors on neurons or non-neuronal cells that modulate RA pathology and associated chronic pain, and it will be beneficial for the development of future therapeutic treatments.

Profiling Arthritis Pain with a Decision Tree

BACKGROUND

Arthritis is the leading cause of work disability and contributes to lost productivity. Previous studies showed that various factors predict pain, but they were limited in sample size and scope from a data analytics perspective.

OBJECTIVES

The current study applied machine learning algorithms to identify predictors of pain associated with arthritis in a large national sample.

METHODS

Using data from the 2011 to 2012 Medical Expenditure Panel Survey, data mining was performed to develop algorithms to identify factors and patterns that contribute to risk of pain. The model incorporated over 200 variables within the algorithm development, including demographic data, medical claims, laboratory tests, patient-reported outcomes, and sociobehavioral characteristics.

RESULTS

The developed algorithms to predict pain utilize variables readily available in patient medical records. Using the machine learning classification algorithm J48 with 50-fold cross-validations, we found that the model can significantly distinguish those with and without pain (c-statistics = 0.9108). The F measure was 0.856, accuracy rate was 85.68%, sensitivity was 0.862, specificity was 0.852, and precision was 0.849.

CONCLUSION

Physical and mental function scores, the ability to climb stairs, and overall assessment of feeling were the most discriminative predictors from the 12 identified variables, predicting pain with 86% accuracy for individuals with arthritis. In this era of rapid expansion of big data application, the nature of healthcare research is moving from hypothesis-driven to data-driven solutions. The algorithms generated in this study offer new insights on individualized pain prediction, allowing the development of cost-effective care management programs for those experiencing arthritis pain.

Remaining Pain in Early Rheumatoid Arthritis Patients Treated With Methotrexate

Objective

To investigate the frequency of remaining pain in early rheumatoid arthritis (RA) after 3 months of treatment with methotrexate as the only disease modifying antirheumatic drug, with a special focus on patients with a good clinical response.

Methods

The study base was cases reported to a population‐based early RA cohort who had followup data from the Swedish Rheumatology Quality Register (n = 1,241). The Disease Activity Score in 28 joints European League Against Rheumatism (EULAR) response criteria were used to evaluate clinical response to treatment as good, moderate, and no response. The primary end point was remaining pain at the 3‐months followup visit, defined as pain >20 mm on a 100‐mm visual analog scale (VAS).

Results

Remaining pain in spite of a EULAR good response at followup was associated with higher baseline disability, using the Health Assessment Questionnaire (adjusted odds ratio [OR] 2.2 [95% confidence interval (95% CI) 1.4–3.4] per unit increase), and less baseline inflammation, using the erythrocyte sedimentation rate (adjusted OR 0.81 [95% CI 0.70–0.93] per 10‐mm increase). Similar associations were detected for remaining pain at followup in spite of low inflammatory activity, defined as a C‐reactive protein level <10. Increase in VAS pain during the treatment period was observed in 19% of the whole cohort, with frequencies in the EULAR response groups of 9% (good response), 15% (moderate response), and 45% (no response).

Conclusion

These results are in line with the hypothesis that a subgroup of early RA patients exhibits pain that is not inflammatory mediated, where alternative treatment strategies to traditional antiinflammatory medications need to be considered.

Patient-reported Outcomes as Predictors of Change in Disease Activity and Disability in Early Rheumatoid Arthritis: Results from the Yorkshire Early Arthritis Register

OBJECTIVE

To assess patient-reported variables as predictors of change in disease activity and disability in early rheumatoid arthritis (RA).

METHODS

Cases were recruited to the Yorkshire Early Arthritis Register (YEAR) between 1997 and 2009 (n = 1415). Predictors of the 28-joint Disease Activity Score (DAS28) and the Health Assessment Questionnaire-Disability Index (HAQ-DI) at baseline and change over 12 months were identified using multilevel models. Baseline predictors were sex, age, symptom duration, autoantibody status, pain and fatigue visual analog scales (VAS), duration of early morning stiffness (EMS), DAS28, and HAQ-DI.

RESULTS

Rates of change were slower in women than men: DAS28 fell by 0.19 and 0.17 units/month, and HAQ-DI by 0.028 and 0.023 units/month in men and women, respectively. Baseline pain and EMS had small effects on rates of change, whereas fatigue VAS was only associated with DAS28 and HAQ-DI at baseline. In patients recruited up to 2002, DAS28 reduced more quickly in those with greater pain at baseline (by 0.01 units/mo of DAS28 per cm pain VAS, p = 0.024); in patients recruited after 2002, the effect for pain was stronger (by 0.01 units/mo, p = 0.087). DAS28 reduction was greater with longer EMS. In both cohorts, fall in HAQ-DI (p = 0.006) was greater in patients with longer EMS duration, but pain and fatigue were not significant predictors of change in HAQ-DI.

CONCLUSION

Patient-reported fatigue, pain, and stiffness at baseline are of limited value for the prediction of RA change in disease activity (DAS28) and activity limitation (HAQ-DI).

Contribution of subjective Disease Activity Score 28 (DAS28) components to the response to treatment of rheumatoid arthritis

We investigated the contributions made by the subjective components of the Disease Activity Score 28 (DAS28) to the treatment response of rheumatoid arthritis (RA). In addition, factors associated with poor response to treatment at 6 months, despite normalization of objective measures, were examined. A total of 426 newly diagnosed RA patients were included. The DAS28-P score (the subjective components of the DAS28 relative to the total components) was calculated as DAS28-P = 0.56 ∗ sqrt(TJC28) + 0.014 ∗ (VAS-GH) /0.56 ∗ sqrt(TJC28) + 0.28 ∗ sqrt(SJC28) + 0.7 ∗ In(erythrocyte sedimentation rate (ESR)) + 0.014 ∗ (VAS-GH). The European League Against Rheumatism (EULAR) response was assessed after 6 months of treatment. Of those who failed to attain good EULAR responses, those for whom the objective measures (the ESR, the C-reactive protein level, and swollen joints) were normalized were defined as having failed treatment because of subjective measures. The median (IQR) DAS28 score at baseline was 4.8 (4.04-5.49) and that after 6 months of treatment 3.21 (2.41-3.95). The DAS28-P score fell significantly from baseline to 6 months in good (0.43 versus 0.28, p < 0.001) and moderate responders (0.44 versus 0.4, p = 0.003), but not in non-responders (0.43 versus 0.45, p = 0.727). Younger age, a lower DAS28 score, and a lower DAS28-P score at baseline were related to a good EULAR response. Subjects who failed to respond because of subjective measures tended to have higher DAS28-P scores at baseline. We found that RA patients with high DAS28-P scores, reflecting subjective measures, were less likely to achieve good EULAR responses 6 months after treatment initiation and tended not to be classified as good responders despite normalization of objective measures.

Discordant inflammation and pain in early and established rheumatoid arthritis: Latent Class Analysis of Early Rheumatoid Arthritis Network and British Society for Rheumatology Biologics Register data

Background

Rheumatoid arthritis (RA) disease activity is often measured using the 28-joint Disease Activity Score (DAS28). We aimed to identify and independently verify subgroups of people with RA that may be discordant with respect to self-reported and objective disease state, with potentially different clinical needs.

Methods

Data were derived from three cohorts: (1) the Early Rheumatoid Arthritis Network (ERAN) and the British Society for Rheumatology Biologics Register (BSRBR), (2) those commencing tumour necrosis factor (TNF)-α inhibitors and (3) those using non-biologic drugs. In latent class analysis, we used variables related to pain, central pain mechanisms or inflammation (pain, vitality, mental health, erythrocyte sedimentation rate, swollen joint count, tender joint count, visual analogue scale of general health). Clinically relevant outcomes were examined.

Results

Five, four and four latent classes were found in the ERAN, BSRBR TNF inhibitor and non-biologic cohorts, respectively. The proportions of people assigned with >80% probability into latent classes were 76%, 58% and 72% in the ERAN, TNF inhibitor and non-biologic cohorts, respectively. The latent classes displayed either concordance between measures indicative of mild, moderate or severe disease activity; discordantly worse patient-reported measures despite less markedly elevated inflammation; or discordantly less severe patient-reported measures despite elevated inflammation. Latent classes with discordantly worse patient-reported measures represented 12%, 40% and 21% of the ERAN, TNF inhibitor and non-biologic cohorts, respectively; contained more females; and showed worse function. In those latent classes with worse scores at baseline, DAS28 and function improved over 1 year (p < 0.001 for all comparisons), and scores differed less at follow-up than at baseline.

Conclusions

Discordant latent classes can be identified in people with RA, and these findings are robust across three cohorts with varying disease duration and activity. These findings could be used to identify a sizeable subgroup of people with RA who might gain added benefit from pain management strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1186-8) contains supplementary material, which is available to authorized users.

Factors predicting pain and early discontinuation of tumour necrosis factor-α-inhibitors in people with rheumatoid arthritis: results from the British society for rheumatology biologics register

Background

We examined pain levels in 2 cohorts assembled from the British Society for Rheumatology Biologics Register (BSRBR), and investigated which factors predicted Bodily Pain scores and discontinuation of TNFα-inhibitors.

Method

Data were retrieved from BSRBR-RA databases for up to 1 year after commencing TNFα-inhibitors (n = 11995) or being treated with non-biologic therapies (n = 3632). Bodily Pain scores were derived from the Short Form-36 (SF36) questionnaire and norm-transformed to allow comparison with UK population averages. Discontinuation data were from physician reports. Other data, including 28-joint disease activity score (DAS28) measurements, were from clinical examination, interview, medical records and self-report questionnaires. DAS28-P was derived as the proportion of DAS28 attributed to patient-reported factors (tender joint count and visual analogue score). Missing baseline variables from both cohorts were imputed into 20 replicate datasets. Odds ratios (OR) and adjusted OR were calculated for higher than median pain within each cohort.

Results

Participants reported moderate to severe pain at baseline, and pain scores remained >1SD worse than normal population standards at 1 year, even when disease activity responded to treatment. Baseline pain was associated with DAS28-P, worse physical function, worse mental health, and DAS28. After logistic regression, independent predictors of higher than median pain at follow up were baseline Bodily Pain score, higher DAS28-P, worse physical function or mental health and co-morbidities. Higher age, male gender, and higher BMI were additional independent predictors of higher pain in participants who received TNFα-inhibitors. Baseline pain was also one of the predictors of discontinuation of the first TNFα-inhibitor within 1 year, as were female gender, current smoking, co-morbidities, extra-articular manifestations and worse function.

Conclusion

Pain persists in people with treated RA, even in those for whom inflammation responds to treatment. Worse pain outcomes are predicted by factors different to those typically found to predict inflammatory disease activity in other studies. Worse pain at baseline also predicts discontinuation of TNFα-inhibitors. Improved pain management should complement inflammatory disease suppression in RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1192-7) contains supplementary material, which is available to authorized users.

[Central regulation of pain in patients with joint disease and approaches to therapy]

The paper reviews investigations studies that have demonstrated that chronic pain syndrome is mixed in rheumatic diseases. The nervous system is involved in its pathogenesis with different frequency and different mechanisms. Under the influence of afferent pain impulses from damaged joints, there are changes in the excitability of spinal cord neurons, which is called central sensitization (CS). A number of patients have enhanced CS and clinical manifestations as neuropathic sensitive phenomena. The mixed model of the development of chronic pain in joint diseases and its presence along with nociceptive (inflammatory) and neuropathic pain components may explain the discrepancy between joint inflammatory and structural changes and pain intensity, the presence of distant pain and sensitive disorders in the areas outside the joint, and sometimes the efficiency of anti-inflammatory therapy. The presence of the neuropathic pain component serves as a rationale for combined therapy by adding centrally acting drugs, such as anticonvulsants.

Effect of Milnacipran on Pain in Patients with Rheumatoid Arthritis with Widespread Pain: A Randomized Blinded Crossover Trial

OBJECTIVE

Clinical trials have shown that serotonin norepinephrine reuptake inhibitors, such as milnacipran, decrease pain in noninflammatory pain conditions such as fibromyalgia and osteoarthritis. We examined the effect of milnacipran on self-reported pain intensity and experimental pain sensitivity among patients with rheumatoid arthritis (RA) with widespread pain and stable RA disease activity.

METHODS

In this double-blind, crossover study, patients with RA with widespread pain, receiving a stable treatment regimen, were randomized (by a random number generator) to receive milnacipran 50 mg twice daily or placebo for 6 weeks, followed by a 3-week washout and crossed over to the other arm for the remaining 6 weeks. The primary outcome was change in average pain intensity, assessed by the Brief Pain Inventory short form. The sample size was calculated to detect a 30% improvement in pain with power = 0.80 and α = 0.05.

RESULTS

Of the 43 randomized subjects, 41 received the study drug, and 32 completed the 15-week study per protocol. On a 0-10 scale, average pain intensity decreased by 0.39 (95% CI -1.27 to 0.49, p = 0.37) more points during 6 weeks of milnacipran treatment compared with placebo. In the subgroup of subjects with swollen joint count ≤ 1, average pain intensity decreased by 1.14 more points during 6 weeks of milnacipran compared with placebo (95% CI -2.26 to -0.01, p = 0.04). Common adverse events included nausea (26.8%) and loss of appetite (9.7%).

CONCLUSION

Compared with placebo, milnacipran did not improve overall, self-reported pain intensity among subjects with widespread pain receiving stable RA medications.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01207453.

Autoantibodies to citrullinated proteins induce joint pain independent of inflammation via a chemokine-dependent mechanism

Objective

An interesting and so far unexplained feature of chronic pain in autoimmune disease is the frequent disconnect between pain and inflammation. This is illustrated well in rheumatoid arthritis (RA) where pain in joints (arthralgia) may precede joint inflammation and persist even after successful anti-inflammatory treatment. In the present study, we have addressed the possibility that autoantibodies against citrullinated proteins (ACPA), present in RA, may be directly responsible for the induction of pain, independent of inflammation.

Methods

Antibodies purified from human patients with RA, healthy donors and murinised monoclonal ACPA were injected into mice. Pain-like behaviour was monitored for up to 28 days, and tissues were analysed for signs of pathology. Mouse osteoclasts were cultured and stimulated with antibodies, and supernatants analysed for release of factors. Mice were treated with CXCR1/2 (interleukin (IL) 8 receptor) antagonist reparixin.

Results

Mice injected with either human or murinised ACPA developed long-lasting pronounced pain-like behaviour in the absence of inflammation, while non-ACPA IgG from patients with RA or control monoclonal IgG were without pronociceptive effect. This effect was coupled to ACPA-mediated activation of osteoclasts and release of the nociceptive chemokine CXCL1 (analogue to human IL-8). ACPA-induced pain-like behaviour was reversed with reparixin.

Conclusions

The data suggest that CXCL1/IL-8, released from osteoclasts in an autoantibody-dependent manner, produces pain by activating sensory neurons. The identification of this new pain pathway may open new avenues for pain treatment in RA and also in other painful diseases associated with autoantibody production and/or osteoclast activation.

Contribution of the subjective components of the disease activity score to the response to biologic treatment in rheumatoid arthritis

OBJECTIVE

A significant proportion of patients with rheumatoid arthritis do not respond adequately to biologic treatment. We hypothesized that lack of response to (biologic) disease-modifying antirheumatic drugs (DMARDs) is high in patients in whom the subjective, patient-reported component of the Disease Activity Score 28 (DAS28) is high at baseline. The primary aim of our present study was to investigate the contribution of the more subjective versus the objective components of the DAS28 to response to biologic agents in RA patients, as well as the changes in this contribution over time. The secondary aim was to examine whether the value of this subjective contribution at baseline affects the response to treatment.

METHODS

The DAS28-P (the subjective components of the DAS28 relative to the total DAS28) was calculated. Patients were derived from the computer-assisted Management in Early Rheumatoid Arthritis Trial-II and the Biologicals and Outcome Compared and Predicted in Utrecht Region in Rheumatoid Arthritis Study. Ordinal logistic regression analyses were performed.

RESULTS

The DAS28-P score at baseline was not associated with the level of response according to European League Against Rheumatism criteria at 3 months. Overall, a significant reduction in the DAS28-P score was observed 3 months after start of treatment, showing a greater reduction of the combined subjective components in good responders.

CONCLUSION

The results reject the hypothesis that the lack of response to biologic DMARDs is especially high in patients in whom the patient-reported component of the DAS28 is high at baseline; these subjective components are not linked to treatment response.