Background and Objectives: Sarcopenia is a notable comorbidity of rheumatoid arthritis (RA), affecting about one third of patients. However, the characteristic of muscle function and its association with RA disease remains unknown. Materials and Methods: This cross-sectional study collected clinical data from a real-world Chinese RA cohort. Sarcopenia was defined as both myopenia and low muscle function (LMF). Myopenia was defined as appendicular skeletal muscle mass index (ASMI) < 7.0 kg/m² in men and <5.7 kg/m² in women. LMF was defined as low muscle strength (LMS, hand grip < 28 kg in men and <18 kg in women) or low physical performance (LPP, 6 m gait speed < 1.0 m/s). Results: Among 1125 RA patients recruited in this study, 928 RA patients were eligible for analysis. The prevalence of sarcopenia, myopenia, LMF, LMS, and LPP in all RA patients was 36.5%, 46.1%, 69.0%, 57.8%, and 37.1%, respectively. According to their trends in age and disease activity, there were 111 (11.9%) patients in the young (age < 50 years) and remission (CDAI ≤ 2.8) subgroup, 199 (21.4%) patients in the young and active (CDAI > 2.8) subgroup, 198 (21.3%) patients in the old (age ≥ 50 years) and remission subgroup, and 420 (45.2%) patients in the old and active subgroup. Compared with the two remission subgroups, respectively, the young and active subgroup had significantly lower grip strength, higher prevalence of sarcopenia, LMF, and LMS, and worse activity function. After adjustment for potential confounders, multivariate multinominal logistic regression analysis showed that the young and active subgroup was positively associated with sarcopenia (OR = 3.193, 95%CI: 1.477–6.899), LMF (OR = 2.390, 95%CI: 1.207–4.731), and LMS (OR = 3.520, 95%CI: 1.743–7.110). Conclusions: Worse muscle strength, rather than reduced physical performance, is more common in patients with active RA at a young age. It underscores the critical need for early identification and intervention of muscle dysfunction to improve their quality of life.

Muscle loss is linked to multiple adverse outcomes, but its impact on rheumatoid arthritis (RA) prognosis is unclear. This study aimed to examine the association between muscle mass and mortality in RA patients. RA patients from the NHANES database were followed for survival until December 31, 2021. Muscle mass was measured using dual X-ray absorptiometry, low muscle mass was defined as appendicular skeletal muscle mass index (ASMI) < 7.0 kg/m² in men or < 5.5 kg/m² in women. The relationship between ASMI and mortality was analyzed using weighted Cox regression. The study included 892 participants (weighted mean [SE] age 52.22 [0.59] years, 57.36% female). During a median (SE) follow-up of 11.44 (0.33) years, 291 deaths (32.62%) were recorded, of which 197 (28.23%) were attributed to cardiovascular disease. In fully adjusted models, a 1 kg/m²increase in ASMI was associated with decreased all-cause and cardiovascular mortality risk by 34% (HR = 0.66, 95% CI 0.50–0.86) and 40% (HR = 0.60, 95% CI 0.38–0.93), respectively. When ASMI stratified, RA with low muscle mass had a 1.42-fold higher risk of all-cause mortality (HR = 1.42, 95% CI 1.01-2.00) and a 2.58-fold higher risk of cardiovascular mortality (HR = 2.58, 95% CI 1.18–5.62) than those with normal muscle mass. Restricted cubic spline analysis showed a nonlinear association between ASMI and cardiovascular (Pnonlinear = 0.04) but not for all-cause mortality (Pnonlinear = 0.25). Muscle loss in RA patients is linked to higher mortality risk, underscoring the need to recognize its harmful effects.

Introduction The burden of rheumatoid arthritis (RA) is profound, although treated with the treat-to-target strategy for RA patients according to the two most influential organisations for rheumatology worldwide. The need to timely achieve the control of disease activity for RA patients, especially for those difficult-to-treat individuals, is still unmet. Besides, the data on the diagnosis and prognosis of RA-related complications or comorbidities such as sarcopenia, cardiovascular diseases (CVD), malignancies and infections in large real-world cohorts are still limited. Therefore, the aim of this large-scale cohort study is to identify the development of clinical, biomedical, histopathological and imaging biomarkers for the diagnosis and prognosis of difficult-to-treat RA, and RA-related complications/comorbidities and to evaluate their impact on the prognosis of RA. Methods and analysis In this real-world multicentre prospective cohort, consecutive RA patients are planned to be recruited during 2024 and 2033 and with at least 5-year follow-up. Sociodemographic characteristics collection, clinical assessment, muscle assessment, histopathological assessment, imaging examination and biological samples collection will be performed at baseline, 1st, 3rd, 6th and 12th month during the first year and subsequently every 6 months until 5 years to repeat the assessments and collect the information of interested outcomes. The outcomes of interest include RA disease outcomes (including disease activity, functional and radiographic indicators) and RA-related complications/comorbidities (eg, sarcopenia, CVD, malignancies and specific infection). Ethics and dissemination Ethical approval has been approved by the Medical Ethics Committee of Sun Yat-sen Memorial Hospital, Sun Yat-sen University (ID: SYSKY-2023-1235-01); the Affiliated Panyu Central Hospital of Guangzhou Medical University (ID: PYRC-2024-214-01); and ShenShan Medical center, Memorial Hospital of Sun Yat-sen University (ID: 2024-SSKY-118-01). All study participants sign an informed consent form. Dissemination of results will occur via national and international conferences, in peer-reviewed journals, public conferences and social media. Trial registration number NCT06233929.

Objective: To characterize the epidemiological characteristics of malignancy in Chinese patients with rheumatoid arthritis (RA) versus American patients and investigate their associated factors. Methods: Data were collected from a real-world Chinese RA population and American patients with RA from the National Health and Nutritional Examination Survey. The prevalence and subtypes of malignancy and their potential associated factors were investigated in both populations. Results: A total of 2,073 Chinese and 2,928 American patients with RA were included. There was a lower prevalence of malignancy in Chinese than in their American counterparts before (5.7% vs. 17.1%) and after matching (6.2% vs. 12.6%, both P < 0.001). Gender discrepancies in malignancy prevalence were observed, with a male predilection for RA with malignancy in China (8.2% vs. 5.5%), while it was the opposite in American patients (10.1% vs. 13.5%, both P < 0.05). The top type of malignancy among male patients with RA was lung cancer in Chinese (2.29%), but non-melanoma skin cancer (3.43%) in American; while among female patients was breast cancer both in Chinese (1.72%) and American (3.43%). Multivariate logistic regression analyses showed that older age (odds ratio (OR) = 1.050) and positive anti-cyclic citrullinated peptide antibody (OR = 2.752) were independently associated with malignancy in Chinese patients with RA, while female (OR = 1.395), older age (OR = 1.033), active smoking (OR = 1.580) and cardiovascular diseases (OR = 1.523) in American patients. Conclusion: The prevalence, subtypes and risk factors of malignancy were substantially different in Chinese patients with RA and their American counterparts, which implied the importance of individualized malignancy screening strategies for patients with RA.

Background and Objectives: Hand joint deformity remains a main cause impairing quality of life in rheumatoid arthritis (RA). This study aimed to investigate the association between biologic and targeted-synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) treatment and the prevalence of hand joint deformity in RA patients. Materials and Methods: This cross-sectional analysis included RA patients recruited between 2019 and 2024. Hand joint deformity was defined as the presence of specific deformity in any of 28 hand joints, including the metacarpophalangeal (MCP) joints I-V, proximal interphalangeal (PIP) joints I-V, and distal interphalangeal (DIP) joints II-V. The key exposure was the use of b/tsDMARDs. Multivariable logistic regression was used to assess the association between b/tsDMARDs treatment and hand joint deformity. Results: A total of 1083 RA patients with a mean age of 52.6 ± 12.4 years and a median disease duration of 5 (2,11) years were included. Hand joint deformity was present in 25.4% (275/1083) of patients. The top three deformed joint locations were PIP V (12.9%, 140/1083), PIP III (11.6%, 126/1083), and PIP IV (10.9%, 118/1083). The top three deformity types were ulnar deviation of MCP II-V (8.0%, 87/1083), boutonniere deformity of II-V fingers (6.8%, 74/1083), and swan neck deformity of II-V fingers (6.7%, 73/1083). In total, 17.4% (188/1083) of patients had received b/tsDMARDs. After 1:1 propensity score matching for age, sex, and disease duration, the prevalence of deformity was significantly lower in patients treated with conventional medicine (csDMARDs and/or GCs) add-on b/tsDMARDs compared to those treated with conventional medicine (27.1% vs. 61.7%, p < 0.001). Multivariable logistic regression analysis showed that b/tsDMARDs use was independently associated with a lower prevalence of hand joint deformity after adjusting for confounding factors (OR = 0.211, 95%CI: 0.129–0.345, p < 0.001). Conclusions: The use of b/tsDMARDs was independently associated with a lower prevalence of hand joint deformity in RA.