Sarcopenia was recently identified as an entity in the ICD-10 classification of October 2016. According to the recommendation of the European Working Group on Sarcopenia in Older People (EWGSOP2), sarcopenia is defined as low muscle strength and low muscle mass, while physical performance is used to categorize the severity of sarcopenia. In recent years, sarcopenia has become increasingly common in younger patients with autoimmune diseases such as Rheumatoid arthritis (RA). Due to the chronic inflammation caused by RA, patients have reduced physical activity, immobility, stiffness, and joint destruction and all of that lead to the loss of muscle mass, muscle strength, disability and significantly lowering the patients’ quality of life. This article is a narrative review about sarcopenia in RA, with a special focus in its pathogenesis and management.

This study compares EQ-5D-3L, EQ-5D-5L, and SF-6D utilities in patients with different musculoskeletal (MSK) disorders, also differing in disease severity as defined by valid clinical indexes. Utilities were measured from a cross-sectional sample of rheumatoid arthritis (N = 114), psoriatic arthritis (N = 57), ankylosing spondylitis (N = 49), and osteopenia/osteoporosis (N = 95) patients. For the first three groups, disease activity (severity) was measured with the DAS-28, DAPSA, and BASDAI clinical indexes, respectively. Mean differences and effect sizes were measured, and agreement between utilities was estimated with the intraclass correlation coefficient and Bland–Altman plots. Higher agreement was observed between EQ-5D-5L and SF-6D, compared to EQ-5D-3L and SF-6D, in all MSK disorder groups and severity levels. In groups with moderate to high severity, agreement between EQ-5D-3L/SF-6D and EQ-5D-5L/SF-6D was between low and fair, and both EQ-5D-3L and 5L utilities were lower than SF-6D (p < 0.001). On the other hand, in remission or low activity groups, agreement was excellent, and SF-6D utilities were again typically higher than EQ-5D-3L/5L, but not significantly. In more severe patients, SF-6D generated significantly higher utilities than EQ-5D-3L and 5L, which is consistent with most previous studies. Such discrepancies could have implications on economic evaluations of interventions targeting patients with MSK disorders.

BackgroundMyostatin is expressed in skeletal muscles and exerts a negative feedback in myogenesis. Chronic inflammation has been associated with increased serum myostatin levels (Baig MH, Front Physiol. 2022).ObjectivesThe calculation of serum myostatin levels in patients with rheumatoid arthritis (RA) and association with disease parameters.MethodsA cross-sectional study of 30 post-menopausal women with RA, classified according to the 1987 ACR criteria. Blood samples were collected and inflammatory markers (erythrocyte sedimentation rate, ESR, and C-reactive protein, CRP) were calculated. Serum myostatin levels were assessed using the ELISA method. Seropositive disease was defined according to a positive history of antibodies against rheumatoid factor (RF) or against citrullinated proteins (ACPA). Disease activity and patient functionality were expressed by using the DAS28 (ESR) and the HAQ-DI scores respectively.ResultsIn our cohort, 47% (n=14) had seropositive disease. Mean values for ESR, CRP, DAS28 (ESR) and HAQ-DI were 29 ± 20 mm, 1.6 ± 2.6 mg/dl, 3.9 ± 1.7 and 0.9 ± 0.6 respectively. The mean serum myostatin levels were 5.9 ± 1.3 μg/ml. According to the DAS28 (ESR) score, 17% (n=5) patients were in disease remission, 20% (n=6) had low disease activity, 40% (n=12) had medium disease activity and 23% (n=8) had high disease activity. Serum myostatin was not associated with disease activity (p=0.32), patient functionality (p=0.08) or the inflammatory burden attributed to active disease (p=0.67 for ESR and p=0.83 for CRP). Seropositive disease did not correlate with serum myostatin levels (p=0.08).ConclusionIn post-menopausal women with rheumatoid arthritis, serum myostatin levels are independent of disease activity, patient functionality, inflammatory burden, RF or ACPA seropositivity. Except for inflammation per se, other disease parameters associated with RA influence the regulation of myostatin.Reference[1]Baig MH, Ahmad K, Moon JS, Park SY, Ho Lim J, Chun HJ, Qadri AF, Hwang YC, Jan AT, Ahmad SS, Ali S, Shaikh S, Lee EJ, Choi I. Myostatin and its Regulation: A Comprehensive Review of Myostatin Inhibiting Strategies. Front Physiol. 2022 Jun 23;13:876078. doi: 10.3389/fphys.2022.876078.Table 1.Association of serum myostatin with disease parameters in RA patients (statistical significance: p<0.05)ParameterCoefficientpAge0.0840.658BMI-0.1560.412Disease duration0.1310.492Seropositive disease-0.8090.084ESR-0.0810.672CRP0.0410.830DAS28 (ESR)-0.1900.315HAQ-DI-0.3220.083Acknowledgements:NIL.Disclosure of InterestsNone Declared.