Background: Inflammatory rheumatic diseases are systemic conditions associated not only with joint inflammation but also with significant alterations in body composition, including loss of lean mass, increased fat mass, and the development of rheumatoid cachexia or sarcopenic obesity. These changes are often independent of body weight or body mass index (BMI) and contribute to functional impairment, increased cardiometabolic risk, and worse clinical outcomes. Despite their clinical relevance, body composition abnormalities remain underrecognized in routine rheumatology practice. Aim: The aim of this narrative review was to summarize current evidence on the pathophysiology, assessment methods, diagnostic criteria, prevalence, clinical significance, and therapeutic implications of body composition abnormalities in inflammatory rheumatic diseases. Material and methods: A narrative review of the literature published between 2004 and 2025 was conducted. Relevant studies, systematic reviews, and clinical guidelines addressing body composition in rheumatoid arthritis, spondyloarthritis, psoriatic arthritis, systemic lupus erythematosus, and other connective tissue diseases were analyzed. Particular attention was given to assessment methods (anthropometry, BIA, DXA, CT, MRI), diagnostic criteria for sarcopenia and cachexia, and the relationship between body composition, disease activity, and treatment. This review was conducted as a narrative synthesis without formal systematic review methodology or quality assessment. Results: Chronic systemic inflammation, physical inactivity, pain, and pharmacotherapy (especially long-term glucocorticoid use) contribute to muscle catabolism, fat redistribution, and the development of unfavorable body composition phenotypes. Sarcopenia prevalence ranges from approximately 15–40% in rheumatoid arthritis and 10–20% in systemic lupus erythematosus. Reduced lean mass and increased visceral adiposity are associated with higher disease activity, greater disability, poorer quality of life, and increased mortality. Advanced assessment techniques such as DXA and imaging modalities allow early detection and monitoring, while effective inflammation control with targeted therapies may partially improve lean mass. Conclusions: Body composition abnormalities are common and clinically significant systemic manifestations of IRDs. Routine assessment using appropriate screening and confirmatory methods may improve risk stratification, support personalized management, and help prevent functional decline and metabolic complications. Integration of body composition evaluation into standard disease monitoring may contribute to more comprehensive and patient-centered care.
Daniszewski et al. (Thu,) studied this question.