Non-inflammatory pain in inflammatory arthritis

How to Distinguish Non-Inflammatory from Inflammatory Pain in RA?

PURPOSE OF THE REVIEW

Managing non-inflammatory pain in rheumatoid arthritis (RA) can be a huge burden for the rheumatologist. Pain that persists despite optimal RA treatment is extremely challenging for patient and physician alike. Here, we outline the latest research relevant to distinguishing non-inflammatory from inflammatory RA pain and review the current understanding of its neurobiology and management.

RECENT FINDINGS

Nociplastic pain is a recently introduced term by the international pain community. Its definition encompasses the non-inflammatory pain of RA and describes pain that is not driven by inflamed joints or compromised nerves, but that is instead driven by a functional reorganisation of the central nervous system (CNS). Insights from all areas of nociplastic pain research, including fibromyalgia, support a personalised pain management approach for non-inflammatory pain of RA, with evidence-based guidelines favouring use of non-pharmacological interventions. Future developments include novel CNS targeting pharmacotherapeutic approaches to treat nociplastic pain.

Navigating the complexity of pain in psoriatic arthritis and axial spondyloarthritis

PURPOSE OF REVIEW

Pain is the most common and often most troublesome feature of chronic autoimmune diseases such as psoriatic arthritis (PsA) and axial spondyloarthritis (AxSpA). A predominant concept is that the main source of pain is from disease-induced tissue inflammation and structural damage, activating peripheral nerve fibers which relay to the central nervous system. This mechanism is nociceptive pain and the presumption has been that controlling inflammation will be sufficient to reduce this form of pain. However, despite control of inflammation, patients may still have significant residual pain.

RECENT FINDINGS

We are learning that there are additional pain mechanisms, neuropathic and nociplastic, that are often operative in patients with rheumatologic conditions, that can significantly influence pain experience, quantitation of disease activity, and may benefit from therapeutic approaches distinct from immunotherapy. Neuropathic pain arises from diseased or damaged nerve tissue and nociplastic pain reflects sensitization of the central nervous system due to multiple genetic, neurobiologic, neural network dysregulation, and psychosocial factors. Pain arising from these mechanisms influence assessment of disease activity and thus needs to be factored into decision-making about immunotherapy efficacy.

SUMMARY

This review addresses the importance of accurately assessing the complex mechanisms of pain experience in patients with PsA and AxSpA to more appropriately manage immunomodulatory, neuromodulatory, and nonpharmacologic therapies.

Five-year follow-up of patients with difficult-to-treat rheumatoid arthritis

OBJECTIVES

To elucidate the long-term outcomes of patients with difficult-to-treat rheumatoid arthritis (D2T RA).

METHODS

We collected data on the clinical course of patients who had been identified as D2T RA in 2018 until 2023. We stratified the patients according to outcomes at the last visit: resolved D2T RA, persistent D2T RA, and mortality. We compared their clinical characteristics and investigated the predictive factors for the resolution of D2T RA or mortality. Furthermore, we investigated the impact of the causes of D2T RA identified in 2018, multidrug resistance, comorbidities, and socioeconomic factors on outcomes in 2023.

RESULTS

Of 173 patients identified as D2T RA in 2018, 150 were included in the analysis. Among them, D2T RA was resolved in 67 (45%), 75 (50%) remained as D2T RA, and 8 (5%) died. Patients with resolved D2T RA were significantly younger at the latest visit (p= 0.02), had a higher proportion of treatment changes during five years (p= 0.002), and had a higher proportion of interleukin-6 receptor inhibitors use in 2023 (p= 0.04) than those in patients with persistent D2T RA or those who died. D2T RA resolved in 38% of patients with multidrug resistance, mainly with treatment changes. Rheumatic disease comorbidity index and glucocorticoid dose escalation were independent risk factors for mortality (odds ratio [OR], 3.50; p= 0.02 and OR, 31.9; p= 0.002, respectively).

CONCLUSION

Further modifications in RA treatment are useful for resolving D2T RA. Multiple comorbidities and glucocorticoid use are associated with mortality.

"Inflammatory or non-inflammatory pain in inflammatory arthritis - How to differentiate it?"

Pain is a significant issue in rheumatoid arthritis (RA) and psoriatic arthritis (PSA) and can have a negative impact on patients' quality of life. Despite optimal control of inflammatory disease, residual chronic pain remains a major unmet medical need in RA. Pain in RA can be secondary to inflammation but can also generate neuroendocrine responses that initiate neurogenic inflammation and enhance cytokine release, leading to persistent hyperalgesia. In addition to well-known cytokines such as TNFα and IL-6, other cytokines and the JAK-STAT pathway play a role in pain modulation and inflammation. The development of chronic pain in RA involves processes beyond inflammation or structural damage. Residual pain is often observed in patients even after achieving remission or low disease activity, suggesting the involvement of non-inflammatory and central sensitization mechanisms. Moreover, fibromyalgia syndrome (FMS) is prevalent in RA patients and may contribute to persistent pain. Factors such as depression, sleep disturbance, and pro-inflammatory cytokines may contribute to the development of fibromyalgia in RA. It is essential to identify and diagnose concomitant FMS in RA patients to better manage their symptoms. Further research is needed to unravel the complexities of pain in RA. Finally, recent studies have shown that JAK inhibitors effectively reduce residual pain in RA patients, suggesting pain-reducing effects independent of their anti-inflammatory properties.

Why most (but perhaps not all) DMARDs work equally well

Biological- or targeted-synthetic DMARD-responses reported in randomized clinical trials, placebo-controlled or head-to-head, in patients with rheumatoid arthritis, psoriatic arthritis or spondyloarthritis are unbelievably similar, when looking across trials performed in the same disease and applying the same primary outcome measures. The exception to this rule may be the response to Janus-kinase-inhibitors, which seem to work 10 % better in all trials (JAK-bonus) This article provides a potential explanation for this remarkable phenomenon, including an explanation for the JAK-bonus. It seems as if JAK-inhibitors exert some inflammation-independent effects on pain, fatigue and wellbeing, and that drug treatment of rheumatic diseases is more than the inhibition of inflammation alone.

Exploring the complexities of pain phenotypes: OMERACT 2023 chronic pain working group workshop

OBJECTIVE

To educate and discuss pain mechanisms (nociceptive, neuropathic, nociplastic) illuminating its possible impact when measuring different outcomes, which may modify, confound and potentially bias the outcome measures applied across various aspects of Rheumatic Musculoskeletal Diseases (RMDs) clinical trials.

METHODS

In the plenary presentations, PM lectured on different pain mechanisms and impact on disease activity assessment. Data from two data sets of RMDs patients, which assessed the prevalence and impact of nociplastic pain were presented and reviewed. Audience breakout group sessions and polling were conducted.

RESULTS

Mixed pain etiologies may differentially influence disease activity assessment and therapeutic decision-making. Polling demonstrated a consensus on the need to assess different types of pain as a phenotype, as it constitutes an important contextual factor (a variable that is not an outcome of the trial, but needs to be recognized [and measured] to understand the study results), and to standardize across RMDs.

CONCLUSION

There is need for a standardized pain measure that can differentiate underlying pain mechanisms.

Reprint of "Residual pain in rheumatoid arthritis: Is it a real problem?"

Pain is a significant issue in rheumatoid arthritis (RA) and can have a negative impact on patients' quality of life. Despite optimal control of inflammatory disease, residual chronic pain remains a major unmet medical need in RA. Pain in RA can be secondary to inflammation but can also generate neuroendocrine responses that initiate neurogenic inflammation and enhance cytokine release, leading to persistent hyperalgesia. In addition to well-known cytokines such as TNFα and IL-6, other cytokines and the JAK-STAT pathway play a role in pain modulation and inflammation. The development of chronic pain in RA involves processes beyond inflammation or structural damage. Residual pain is often observed in patients even after achieving remission or low disease activity, suggesting the involvement of non-inflammatory and central sensitization mechanisms. Moreover, fibromyalgia syndrome (FMS) is prevalent in RA patients and may contribute to persistent pain. Factors such as depression, sleep disturbance, and pro-inflammatory cytokines may contribute to the development of fibromyalgia in RA. It is essential to identify and diagnose concomitant FMS in RA patients to better manage their symptoms. Further research is needed to unravel the complexities of pain in RA. Finally, recent studies have shown that JAK inhibitors effectively reduce residual pain in RA patients, suggesting pain-reducing effects independent of their anti-inflammatory properties.

Precision management of post-COVID pain: An evidence and clinical-based approach

Background Pain after a SARS-CoV-2 acute infection (post-COVID pain) is becoming a new healthcare emergency but remains underestimated and most likely undertreated due to a lack of recognition of the phenomenon and knowledge of the underlying pain mechanisms. Evidence supporting any particular treatment approach for the management of post-COVID pain is lacking. Large variability in the patient response to any standard pain treatments is clinically observed, which has led to calls for a personalized, tailored approach to treating patients with chronic post-COVID pain (i.e. 'precision pain medicine'). Applying the global concerted action towards precision medicine to post-COVID pain could help guide clinical decision-making and aid in more effective treatments. Methods The current position paper discusses factors to be considered by clinicians for managing post-COVID pain ranging from identification of the pain phenotype to genetic consideration. Results The ability of clinicians to phenotype post-COVID pain into nociceptive, neuropathic, nociplastic or mixed type is suggested as the first step to better planification of a treatment programme. Further, the consideration of other factors, such as gender, comorbidities, treatments received at the acute phase of infection for onset-associated COVID-19 symptoms, factors during hospitalization or the presence of emotional disturbances should be implemented into a treatment programme. Conclusions Accordingly, considering these factors, management of post-COVID pain should include multimodal pharmacological and non-pharmacological modalities targeting emotional/cognitive aspects (i.e. psychological and/or coping strategies), central sensitization-associated mechanisms (i.e. pain neuroscience education), exercise programmes as well as lifestyle interventions (e.g. nutritional support and sleep management). SIGNIFICANCE: This position paper presents an evidence-based clinical reasoning approach for precision management of post-COVID pain.