OBJECTIVES:This observational study examined whether central pain sensitivity is associated with fatigue in RA and whether such associations are explained by pain severity or inflammation. METHODS:Participants with RA provided self-report fatigue (Bristol Rheumatoid Arthritis Fatigue Multidimensional Questionnaire-BRAF-MDQ), pain severity (summated numerical rating scales) and self-reported pain sensitivity (central aspects of pain-CAP) data at baseline (n = 194) and 3 months (n = 114) while under usual care. CAP was modified (M-CAP) by removing the fatigue-associated item. Pain sensitivity was also assessed by 'static' (pressure pain detection threshold) and 'dynamic' (temporal summation, conditioned pain modulation) quantitative sensory testing (QST). Inflammation was assessed using 28-joint disease activity score (DAS28) tender/swollen joint counts, CRP and US imaging (greyscale, power Doppler). Associations between fatigue and central pain sensitivity were explored with multivariable linear-regression modelling. RESULTS:Baseline M-CAP and pain severity were each associated with higher fatigue at baseline (M-CAP: rho = 0.77, P ≤ 0.001; pain: rho = 0.53, P ≤ 0.001) and at 3 months follow-up (M-CAP: rho = 0.72, P ≤ 0.001; pain: rho = 0.47, P ≤ 0.001). M-CAP and pain remained significantly associated with baseline fatigue when included in a single regression model (M-CAP: β = 0.65, P < 0.001; pain: β = 0.21, P < 0.001; R2 = 0.62, P < 0.001). In longitudinal regression models, a decrease in M-CAP was significantly associated with a reduction in fatigue. QST indices and markers of inflammation were not consistently associated with fatigue. CONCLUSION:Self-reported central pain sensitivity (M-CAP) is a strong driver of fatigue over and above inflammation and pain intensity. Treatments targeting central pain mechanisms may be effective at also reducing fatigue in individuals with RA.

OBJECTIVE:The objective of this study was to assess the role of comorbidities measurements in interstitial lung disease (ILD) in patients with RA. METHODS:The data were from two consecutive multicentre, prospective RA inception cohorts, including baseline socio-demographic, clinical, treatment, laboratory and functional features. Comorbidity burden was assessed using a count of major comorbidities, the Rheumatic Disease Comorbidity Index (RDCI) and the Charlson Comorbidity Index (CCI). Associations between comorbidities and the development of ILD were explored, adjusted for clinical factors using multivariable logistic regression analyses. RESULTS:The data from 2701 patients were included, and the median follow-up time was 6 years. In total, 101 patients (3.7%) were diagnosed with ILD. Twelve (0.44%) had the diagnosis at baseline, 46 were diagnosed during follow-up, and 43 were identified from death certificates. In multivariable analyses, age at onset [adjusted odds ratio (aOR) 1.03, 95% CI 1.01-1.05], seropositivity (aOR 2.58, 95% CI 1.38-4.81) and ever smoking (aOR 1.70, 95% CI 1.04-2.79) were associated with ILD diagnosis. Higher lung comorbidity burden measured using the lung disease component of the RDCI (aOR 4.59, 95% CI 2.68-7.88) was associated, as was using the entire index (aOR 1.32, 95% CI 1.07-1.63). The association did not remain when assessing comorbidity with alternative measures. CONCLUSION:The method chosen to assess the comorbidity burden affected whether baseline comorbidity was associated with subsequent ILD development. This study demonstrates that a specific Rheumatic Disease Comorbidity Index reveals associations not detected by generic tools or simple counts. Baseline lung comorbidities should be added to the known list of risk factors for ILD and aid targeted screening in the context of RA.

Chronic or persistent pain can limit an individual’s ability to work or be productive at work, creating substantial societal and economic burden. Despite this, evidence-based work‑related advice and support for people with chronic pain is inconsistent. The Pain‑at‑Work Toolkit was co‑created with people living with pain, health care professionals, and employers to increase knowledge of employee rights, improve access to workplace support, and provide guidance on lifestyle behaviors that facilitate pain self‑management. This study aimed to establish the feasibility of conducting a definitive cluster randomized controlled trial comparing access to the Pain‑at‑Work Toolkit plus optional occupational therapist telephone support (intervention) with support-as-usual (SAU) from the employer (control). Primary outcomes were feasibility, acceptability, usability, and safety of the digital intervention. We also assessed the feasibility of candidate primary and secondary outcomes and tested research processes required for a definitive trial. We conducted an open‑label, parallel, two‑arm pragmatic feasibility cluster randomized controlled trial with exploratory health‑economics analysis and a nested qualitative study. Eligible organizations were based in England, had ≥10 employees, and were recruited through professional networks and direct approach. Individual participants were working adults aged ≥18 years, with internet access and self‑reported chronic pain interfering with their ability to undertake or enjoy productive work. A restricted 1:1 cluster‑level randomization allocated organizations to the intervention or control arms. After organizational and individual consent, participants completed a web‑based baseline survey (T0) assessing work capacity, health and wellbeing, and health‑care resource use. Follow‑up occurred at 3 months (T1) and 6 months (T2). Feasibility outcomes included recruitment, intervention fidelity (delivery, reach, uptake, engagement), retention, and follow‑up completion. Qualitative interviews with employees and stakeholders at T2 explored acceptability and contextual factors influencing delivery and uptake. A total of 380 employees from 18 organizations participated. Recruitment exceeded targets at both organizational and individual levels, demonstrating strong feasibility and engagement. Follow‑up completion met predefined feasibility criteria but showed variability, largely due to employee turnover, providing realistic attrition estimates for a future trial. Outcome measures showed acceptable completion rates and variability, supporting their suitability for use in a future definitive trial. Employees and stakeholders reported high acceptability of the Pain‑at‑Work Toolkit, and qualitative findings highlighted improved knowledge, confidence, and self‑management among employees. Stakeholders endorsed the Toolkit’s relevance and practicality within workplace settings. The feasibility trial demonstrated that the Pain‑at‑Work Toolkit and trial procedures are acceptable, scalable, and deliverable across diverse workplaces. Findings identify responsive outcome measures, emphasize the need for strengthened retention strategies, and support the Toolkit’s use as a standalone intervention. Overall, the study provides a strong foundation for progressing to a fully powered definitive trial. ClinicalTrials.gov NCT05838677; https://clinicaltrials.gov/study/NCT05838677 International Registered Report Identifier (IRRID): DERR1-10.2196/51474 RR2-10.2196/51474

Public involvement is standard practice to enhance the quality, equity and impact of musculoskeletal pain research. In this review, we aimed to reflect on our own learning journey across multiple musculoskeletal projects and identify lessons learned from meaningful involvement. We then consider the changes needed at the researcher, funder and institutional levels to support involvement as a driver of relevance and impact. This is a narrative position paper drawing on experiential learning from three musculoskeletal pain studies and ongoing community engagement. We reflected on what we have learned from public contributors in our research, focusing on how involvement reshaped study priorities and tools. Lessons were synthesised to highlight recurring themes, supported by reference to reviews, guidance and empirical studies. Across all projects, several key themes emerged: (1) emphasis on purpose rather than process; (2) co-production and partnership rather than review; (3) flexibility and adaptation rather than predetermined steps; (4) relevant public contributors and partners; (5) focus on ‘learning’ rather than ‘doing’; and (6) approaches to diversity and inclusion. Public partnerships should be a collaborative, transformative, relational and learning-based process that reshapes all aspects of research. Realising this potential might require flexible funding for early engagement, training in facilitation and reflexivity, sustained support beyond the research project to promote impact, and taking steps beyond building more infrastructure towards strengthening the systems that enable involvement to work effectively.

Purpose The study explored the views of organisational stakeholders who participated in the feasibility trial of the Pain-at-Work Toolkit towards the implementation of the toolkit in ‘real-world’ workplace settings. This digital toolkit was co-created with healthcare professionals, employers, and people with chronic pain and aimed to inform and enable individuals to self-manage their chronic pain at work. Design/methodology/approach A qualitative study using semi-structured interviews with 15 stakeholders from 12 organisations that participated in a feasibility trial of the Pain-at-Work Toolkit. Purposive sampling was used to ensure the inclusion of stakeholders with management or supportive roles who have responsibility for the health and wellbeing of employees. Findings The findings illuminate three key themes: not all disabilities are visible; not all line managers are equal; and who has control? These surmise that invisible disabilities such as chronic pain are underestimated, poorly understood, and inconsistently provisioned for in organisational policies. It highlights the key role that line managers play in employee disclosure and access to support but demonstrates that line managers vary in their delivery of support to employees. Lastly, it explores stakeholder perceptions of the roles of the employer relative to the employee with chronic pain. It confirms the need for additional resources to plug organisational gaps and give workers tools to self-manage their pain at work. Originality This study indicates the need for resources / supports to upskill line managers so they can intervene to proactively support employees with chronic pain to reduce sickness absence and presenteeism (working when unwell). The research demonstrates organisational stakeholders’ interest in a multi-faceted approach to help employees self-manage chronic pain in all types at work, such as that provided by the Pain-at-Work Toolkit. In addition, it clearly identifies the potential for complementary resources to educate and facilitate line managers to better support their staff.

Background:Knee pain reduces activity, while inactivity can increase pain. The central nervous system modulates both pain and activity. The 8-item Central Aspects of Pain (CAP) questionnaire measures self-reported symptoms associated with current and future knee pain severity and psychophysical evidence of central pain sensitivity. The objective was to explore associations between CAP and physical inactivity in people with knee pain. Methods:Participants from the Investigating Musculoskeletal Health and Wellbeing cohort who reported their knee as their most troublesome joint with numerical rating scale pain severity ≥1/10 completed questionnaires at baseline and 12 months addressing demographic and clinical characteristics, CAP questionnaire, and physical inactivity (Frail Non-Disabled questionnaire item). Chi-squared, correlations and multivariable logistic regression were performed. Results:Seven hundred twenty-two participants provided baseline data and 404 longitudinal data. Higher baseline CAP scores were associated with higher baseline pain severity {OR: 1.25 (95% confidence interval [CI]: 1.02-1.53); P = 0.032} and physical inactivity (OR: 1.18 [95% CI: 1.11-1.25]; P < 0.001). Increasing CAP scores over 12 months were associated with becoming physically inactive (OR: 1.16 [95% CI: 1.01-1.32]; P = 0.032). The effects of CAP on physical inactivity were not fully explained by pain severity nor by any single characteristic of widespread pain distribution, emotional or cognitive factors, sleep disturbance, or fatigue. Conclusion:Central aspects of pain questionnaire displays cross-sectional and longitudinal associations with physical inactivity. Central nervous system manifestations of pain appear to link pain with physical activity and may be more important than pain severity.

Objectives: Histological osteochondral characteristics of inflammation, fibrosis, vascularity, cartilage islands, vessels entering cartilage, thickened trabeculae and cysts are associated with bone marrow lesions (BMLs) in human knee osteoarthritis (OA). We identified and developed a method for scoring comparable pathology in two rat OA knee pain models. Methods: Rats (n = 8-10 per group) were injected with monoiodoacetate (MIA) or saline, or underwent meniscal transection (MNX) or sham surgery. Pain behaviour (weight bearing asymmetry and mechanical hindpaw withdrawal thresholds (PWTs)) were measured and knee samples obtained. Features associated with BMLs were evaluated using haematoxylin and eosin or Safranin-O stained knee sections. Sections were scored for chondropathy, osteophytes, synovitis and with the human OA Bone Score modified for rats (rOABS). rOABS reliability was assessed with intraclass correlation coefficient (ICC), groups were compared using Mann-Whitney U-tests, and associations examined with Spearman's rho. Results: OABS features were more prevalent in each OA pain group than in controls. rOABS displayed good interrater reliability (ICC = 0.79). rOABS was higher in each model than controls; MIA 3.0 (2.3-4.0) vs vehicle 0.0 (0.0-0.0), and MNX 4.0 (2.3-4.8) vs sham 0.0 (0.0-0.0), each p <0.003. rOABS was associated with OA cartilage involvement (rho = 0.69, p < 0.001), osteophyte (rho = 0.61, p < 0.001) and synovial inflammation (rho = 0.76, p < 0.001). Higher rOABS was associated with pain behaviour: weight bearing asymmetry (rho = 0.65, p < 0.001) and PWT (rho = -0.47, p = 0.003). Conclusions: Subchondral pathology in rat OA models resembles human subchondral BMLs. rOABS reliably measured subchondral pathology and was associated with OA structure and pain behaviour.

Osteoarthritis (OA) pain is associated with structural changes in the joint, which are usually quantified by imaging techniques. It is anticipated that structural disease modifying OA drugs (DMOADs) would reduce the burden of OA pain. However, nociceptive pain is moderated by the central nervous system. Central sensitization, increased activity in central nervous system neurones in response to a standard nociceptive input, is one reason why disease modification might not effectively relieve OA pain. Central sensitization may result from facilitated central neuronal activity, or inadequate inhibition by endogenous analgesic mechanisms. It changes the experience of pain: its severity, distribution and qualities, and its emotional and cognitive dimensions. Central sensitization can be a barrier to analgesic benefit from treatments directed at joint structure, and central pain processing can obscure analgesic benefit from structural modification in randomised controlled trials. Indices of central pain hypersensitivity might reflect central sensitization in humans. They include self-report questionnaires such as the Central Aspects of Pain (CAP) and short form Central Sensitization Inventory (CSI-9), and quantitative sensory testing (QST) modalities of Pressure Pain detection Thresholds distant to the affected joint, Temporal Summation, and Conditioned Pain Modulation. Understanding, measuring, managing and adjusting for central pain hypersensitivity should increase the power of clinical trials to demonstrate that DMOADs not only improve joint imaging outcomes, but also improve pain, the predominant clinical problem of OA.

Rheumatoid arthritis (RA) is a chronic condition where pain often persists despite controlled inflammation. Central sensitisation (CS), characterised by an amplified response of the central nervous system to nociceptive inputs, drives this persistent pain. While physical activity is important for health, its effectiveness in reducing pain and CS in RA is unclear. This study investigates whether self-reported physical activity levels influence pain and CS indices. Ninety-two participants with RA from the Central Aspects of Pain in RA (CAP-RA) cohort completed the International Physical Activity Questionnaire (IPAQ) at baseline, categorising physical activity levels as Low, Moderate, or High. Quantitative Sensory Testing (QST) modalities, including pressure pain thresholds (PPT), temporal summation (TS), and conditioned pain modulation (CPM) were used as CS indices. Pain severity was the sum of 3 numerical rating scales (NRS) from the painDETECT questionnaire. Disease activity was assessed using the Disease Activity Score 28 (DAS28). Sixty-four participants provided 3-month follow-up data. Spearman’s correlations and multivariable linear regressions explored associations between physical activity, CS indices, and pain at baseline and over time. The median age of participants was 65 (range: 30,85) years. The majority were female (87%). Participants reported moderate pain, with a median pain severity score of 20 (IQR 16, 23) out of 30, and moderate disease activity (median DAS28: 4.5 [IQR 3.8,5.2]). DAS28 decreased by a median of -0.14 (IQR -1.1,+0.7), and median CRP decreased from 5.0 mg/L (IQR 2.0,8.0) to 4.5 mg/L (IQR 2.0,7.0) from baseline to follow-up. About half (54%) reported low physical activity levels, with no significant group change in physical activity from baseline to follow-up. However, 46% of participants transitioned between activity categories, indicating some movement in physical activity levels. Bivariate correlations revealed no significant associations between baseline physical activity and CS indices or pain, nor between change in physical activity and change in CS indices or pain. Multivariable linear regression showed that increases in CS indices and pain severity were most strongly predicted by their baseline values (β = range -1.05 to -0.25, all p < 0.05), but not by physical activity levels. Additionally, male sex significantly predicted increased TS (pain sensitivity) (β = 1.28 ,p =0.01), and high baseline swollen joint count was a significant predictor for increased pain severity after 3 months (β = 0.31, p = 0.02). These findings indicate that people with RA who are more physically active do not tend to have lower pain sensitivity or pain, either at baseline or over time. Other factors, such as sex and inflammation, might have a greater impact on CS and pain than physical activity. This highlights the need for tailored interventions that effectively target central pain mechanisms to improve pain management in RA, over and above advice to increase physical activity. A.A. Ibrahim: None. S. Smith: None. V. Georgopoulos: None. D. McWilliams: Grants/research support; DM-grant support from Pfizer and Eli Lilly. D.A. Walsh: Consultancies; Since 2015 he has undertaken consultancy through the University of Nottingham to AbbVie Ltd, Pfizer Ltd, Eli Lilly and Company, Love Productions, Reckitt Benckiser Health Limited and GSK (each non-pe). Honoraria; he has received speaker fees from the Irish Society for Rheumatology (personal pecuniary). Grants/research support; he has been responsible for research funded by Pfizer, Eli Lilly, UCB Pharma (non-personal, pecuniary); he receives salary from the University of Nottingham, who have received funding for that purpose. Other; he has contributed to educational materials via the University of Nottingham, supported by Medscape Education, New York, International Association for the Study of Pain, and Osteoarthritis Research.

Introduction:The central nervous system (CNS) contributes to pain perception across musculoskeletal conditions. The central aspects of pain (CAP) questionnaire captures a single score associated with quantitative sensory testing (QST) evidence of CNS dysfunction validated in knee osteoarthritis. Objectives:Given the different pathophysiology of rheumatoid arthritis (RA), an inflammatory polyarthritis, this cross-sectional study assessed CAP's psychometric properties and its association with pain in RA. Methods:Adults with RA were recruited from Nottinghamshire, London, and Cardiff. Participants completed CAP and reported pain using a numerical rating scale. A subgroup underwent additional assessments, including quantitative sensory testing (QST; Pressure Pain detection Threshold, Temporal Summation, Conditioned Pain Modulation), Disease Activity Score-28, C-reactive protein, questionnaires addressing pain and related characteristics, and Central Sensitization Inventory short form (CSI-9). Cronbach alpha, confirmatory factor (CFA), and Rasch measurement theory assessed CAP's reliability and validity. Multivariable linear regression modelled contributions to pain by inflammation indices and CAP or CSI-9. Results:The 380 participants (73% female, median 63 years) reported average pain over the past 4 weeks of 6/10 and a CAP score of 9/16. Central aspects of pain demonstrated acceptable reliability (ICC(2,1) = 0.71), CFA fit (comparative fit index = 0.99, Tucker-Lewis index = 0.99, root mean square error of approximation = 0.034, standardized root mean residuals = 0.03), and internal consistency (α = 0.82). Central aspects of pain was significantly associated with pain (0.50 ≤ β ≤ 0.57) but not QST. Central aspects of pain explained 33% of pain variance, rising to 42% with inflammation, age, sex, and body mass index. Central Sensitization Inventory-9 correlated with pain, not QST and explained less pain variance than CAP. Conclusion:Central aspects of pain is reliable and valid for use with people with RA and explains RA pain variance better than inflammation or CSI-9.

Background Central sensitisation (CS) increases musculoskeletal pain. Quantitative sensory testing (QST) or self-report questionnaires might indicate CS. Indices of CS might be suppressed by exercise, although the optimal exercise regimen remains unclear. Objectives We conducted a systematic review and network meta-analysis (NMA) to investigate effectiveness of different exercise regimens on these CS indices in adults. Methods We searched 6 electronic databases from inception to November 2023. Meta-analysis of randomised controlled trials (RCTs) investigated effects of exercise on all CS indices. Two independent reviewers assessed risk of bias. NMA of RCTs compared CS indices between exercise types. Sensitivity analysis using only high-quality studies was performed to verify the robustness of our results. Certainty was assessed using the GRADE approach. Results Of the 249 eligible studies identified, 164 were RCTs, of which 89 provided data suitable for NMA. Meta-analysis revealed large improvement of post-intervention CS indices compared to baseline (SMD −0.81, 95 % CI −0.93 to −0.70). All reported categories of exercise, except stretching exercise alone, were more effective than non-exercise controls. Combined exercises that include stretching together with strengthening exercises (SMD −1.67, 95 % Credible Interval (CrI) −2.41 to −0.97), or strengthening, stretching and aerobic components (SMD −1.61, 95 % CrI −2.74 to −0.56) were most effective at reducing CS indices compared to non-exercise controls. Sensitivity analysis confirmed the robustness of our findings, particularly for combined stretching and strengthening exercise. Conclusions Our meta-analysis suggested that various exercise interventions are effective in improving CS. Multi-component exercise tends to be the most effective, but some exercise combinations might be better than others. Combined exercise featuring strengthening and stretching components, with or without aerobic exercise, shows the greatest likelihood among other combinations of being the optimal exercise type. These findings might have utility informing future trials and personalising treatment strategies for people with CS features.

Abstract Background Pain, the primary complaint in rheumatoid arthritis (RA), is multifaceted, and may be driven by inflammatory disease activity and central sensitisation. We aimed to ascertain what proportion of RA pain severity is explained by markers of inflammation and quantitative sensory testing (QST) indices of central sensitisation. Methods This was a cross-sectional analysis of data from individuals with clinically active RA. Pain severity was assessed using numerical rating scales and inflammation via 28-joint Disease Activity Score (DAS28) and Ultrasound (Greyscale, Power Doppler). Pain sensitivity was assessed by ‘static’ (tibialis anterior or brachioradialis pressure pain detection threshold-PPT-TA/PPT-BR) and ‘dynamic’ (temporal summation-TS, conditioned pain modulation-CPM) QST. Bivariate associations used Spearman’s correlation coefficients, and multivariable linear regression models determined relative contributions to pain severity. Results In bivariate analyses of N = 96 (age 65 ± 10y, 77% females) people with RA, pain severity was significantly associated with inflammation indices (r = 0.20 to 0.55), and CPM (r=-0.26). In multivariable models that included TS, CPM, age, sex, and body mass index, inflammation indices remained significantly associated with pain severity. Multivariable models explained 22 to 27% of pain variance. Heterogeneity was apparent for associations with pain between subscores for pain now, strongest or average over the past 4-weeks. Conclusions In individuals with clinically active RA, markers of inflammatory disease activity best explain RA pain with only marginal contributions from QST indices of central sensitisation. Although inflammation plays a key role in the experience of RA pain, the greater proportion of pain severity remains unexplained by DAS28 and ultrasound indices of inflammation.

Introduction The association between chronic pain and frailty might indicate that pain is an independent driver of frailty but might alternatively be explained by inclusion within frailty identification tools of morbidities that commonly lead to chronic pain. This research examines the extent to which the association of pain with frailty might be attributed to morbidities. Methods A cross-sectional analysis of older people in a UK cohort with or at risk of musculoskeletal problems or frailty (Investigating Musculoskeletal Health and Wellbeing study), used multivariable logistic regression and Z-tests to assess the degrees of associations of pain (McGill Pain Rating Index), and painful and non-painful morbidity counts with frailty (modified FRAIL questionnaire). Results Data were from 2,185 participants, 56% female, median age 73 (range 60 to 96) years. 430 (20%) participants were classified as frail. In a fully adjusted standardised model, pain (aOR 2.07 (95%CI 1.83 to 2.33) and ‘any’ morbidity aOR (1.74 (95%CI 1.54 to 1.97) were both significantly associated with frailty. When morbidity was subclassified as painful or non-painful, painful (aOR 1.48 (95%CI 1.30 to 1.68) and non-painful (aOR1.39 (95%CI 1.24 to 1.56)) morbidities each were associated with frailty, as also was pain (aOR 2.07 (95%CI 1.83 to 2.34, p < 0.001). Conclusions Pain is associated with frailty, over and above any effect of painful and non-painful morbidities. This forms the justification for future research which focuses on pain management in the identification, prevention, and treatment of frailty.

Purpose (the aim of the study): Bone marrow lesions (BMLs) are detected by MRI in the in human osteoarthritis (OA) subchondral bone and associated with pain. We previously described 7 histological features associated with BMLs from which we developed the Osteoarthritis Bone Score (OABS) for human subchondral bone. We now describe parallel histopathological features in rat OA, and validate a rat version of the OABS (rOABS).

Abstract Background/Aims Disease Activity Score 28 (DAS28), ultrasound, quantitative sensory testing (QST) and central aspect of pain (CAP) questionnaire measure disease activity and pain hypersensitivity. We investigated their inter-rater and test-retest reliability in Central Aspects of Pain in Rheumatoid Arthritis (CAP-RA) participants. Methods Participants who attended the CAP-RA study visit and agreed to one or more reliability assessments were included. The same two raters completed all assessments, including clinical examination for DAS28, using a single blood sample per participant. QST modalities in the sequence: Pressure Pain detection Threshold (PPT) at the medial joint line of the most painful knee, tibialis anterior and contralateral brachioradialis, Temporal Summation (TS) at rectus femoris of the most painful knee and Conditioned Pain Modulation (CPM), with ischaemic arm pain conditioning and PPT at tibialis anterior. Ultrasound followed the Backhaus 7 protocol, plus the knee. Two trained sonographers scored each joint scan for grey scale (GS), power Doppler and a combined score (PDUS) using EULAR-OMERACT methodology. Joint scores were summated to give an overall score for GS, Doppler and PDUS. Participants could complete questionnaires at invitation, prior to and at baseline, 1-week post-baseline, prior to and at follow-up visit. Any combination of questionnaires completed within 7 days of each other assessed repeatability. Data were assessed for normality, interclass correlation coefficients, and Bland and Altman plots in R studio. Results 196 people were recruited into CAP-RA (median (IQR)) age 66 (58-75) y, 139 (75%) female, 190 (98%) white. 97 (49%) undertook study visits. Characteristics of the 66 people undertaking reliability did not significantly differ from the total population. Measurements are shown in Table 1. Moderate to excellent reliability was found across all measures except CPM (Table 1). The swollen joint count was the least reliable of the DAS28 components. Conclusion Measures of inflammatory disease activity and pain sensitivity are at least moderately reliable within a research context. Only low reliability for CPM might indicate imprecision, or reflect fluctuations in symptoms or pain sensitivity. High reliability of DAS28 and US might reflect relative stability of clinical signs of inflammation. Suppressing day-to-day fluctuations could reduce the unpredictability of rheumatoid arthritis. Disclosure S.L. Smith: None. V. Georgopoulos: None. O. Ifesemen: None. E. Ferguson: None. R.J. Wakefield: None. D. Wilson: None. P. Buckley: None. D. Platts: None. S. Ledbury: None. D.F. McWilliams: Grants/research support; Eli Lilly, Pfizer, GSK, Orion, UCB. D.A. Walsh: Grants/research support; Eli Lilly, Pfizer, GSK, Orion, UCB.

Background/Aims Disease Activity Score 28 (DAS28), ultrasound, quantitative sensory testing (QST) and central aspect of pain (CAP) questionnaire measure disease activity and pain hypersensitivity. We investigated their inter-rater and test-retest reliability in Central Aspects of Pain in Rheumatoid Arthritis (CAP-RA) participants. Methods Participants who attended the CAP-RA study visit and agreed to one or more reliability assessments were included. The same two raters completed all assessments, including clinical examination for DAS28, using a single blood sample per participant. QST modalities in the sequence: Pressure Pain detection Threshold (PPT) at the medial joint line of the most painful knee, tibialis anterior and contralateral brachioradialis, Temporal Summation (TS) at rectus femoris of the most painful knee and Conditioned Pain Modulation (CPM), with ischaemic arm pain conditioning and PPT at tibialis anterior. Ultrasound followed the Backhaus 7 protocol, plus the knee. Two trained sonographers scored each joint scan for grey scale (GS), power Doppler and a combined score (PDUS) using EULAR-OMERACT methodology. Joint scores were summated to give an overall score for GS, Doppler and PDUS. Participants could complete questionnaires at invitation, prior to and at baseline, 1-week post-baseline, prior to and at follow-up visit. Any combination of questionnaires completed within 7 days of each other assessed repeatability. Data were assessed for normality, interclass correlation coefficients, and Bland and Altman plots in R studio. Results 196 people were recruited into CAP-RA (median (IQR)) age 66 (58-75) y, 139 (75%) female, 190 (98%) white. 97 (49%) undertook study visits. Characteristics of the 66 people undertaking reliability did not significantly differ from the total population. Measurements are shown in Table 1. Moderate to excellent reliability was found across all measures except CPM (Table 1). The swollen joint count was the least reliable of the DAS28 components. Conclusion Measures of inflammatory disease activity and pain sensitivity are at least moderately reliable within a research context. Only low reliability for CPM might indicate imprecision, or reflect fluctuations in symptoms or pain sensitivity. High reliability of DAS28 and US might reflect relative stability of clinical signs of inflammation. Suppressing day-to-day fluctuations could reduce the unpredictability of rheumatoid arthritis. Disclosure S.L. Smith: None. V. Georgopoulos: None. O. Ifesemen: None. E. Ferguson: None. R.J. Wakefield: None. D. Wilson: None. P. Buckley: None. D. Platts: None. S. Ledbury: None. D.F. McWilliams: Grants/research support; Eli Lilly, Pfizer, GSK, Orion, UCB. D.A. Walsh: Grants/research support; Eli Lilly, Pfizer, GSK, Orion, UCB.

BACKGROUND:Neuropathic-like pain, fatigue, cognitive difficulty, catastrophizing, anxiety, sleep disturbance, depression and widespread pain associate with a single factor in people with knee pain. We report the Central Aspects of Pain questionnaire (CAP) to characterize this across painful musculoskeletal conditions. METHODS:CAP was derived from the 8-item CAP-Knee questionnaire, and completed by participants with joint pain in the Investigating Musculoskeletal Health and Wellbeing survey. Subgroups had OA, back pain or FM. Acceptability was evaluated by feedback and data missingness. Correlation coefficients informed widespread pain scoring threshold in relation to the other items, and evaluated associations with pain. Factor analysis assessed CAP structure. Intraclass Correlation Coefficient (ICC) between paper and electronic administration assessed reliability. Friedman test assessed score stability over 4 years in people reporting knee OA. RESULTS:Data were from 3579 participants (58% female, median age 71 years), including subgroups with OA (n = 1158), back pain (n = 1292) or FM (n = 177). Across the three subgroups, ≥10/26 painful sites on the manikin scored widespread pain. Reliability was high [ICC = 0.89 (95% CI 0.84-0.92)] and CAP scores fit to one- and two-factor model, with a total CAP score that was associated with pain severity and quality (r = 0.50-0.72). In people with knee pain, CAP scores were stable over 4 years at the group level, but displayed significant temporal heterogeneity within individual participants. CONCLUSIONS:Central aspects of pain are reliably measured by the CAP questionnaire across a range of painful musculoskeletal conditions, and is a changeable state.