Osteosarcopenia in Older Adults With Rheumatoid Arthritis: Clinical Correlates and Its Association With Rheumatoid Cachexia.

Abstract

Objectives: To determine the prevalence of osteosarcopenia in older patients with rheumatoid arthritis (RA) compared with age- and sex-matched controls and to examine its relationship with RA-related clinical, nutritional, and functional parameters, including rheumatoid cachexia (RC).

Methods: This retrospective cross-sectional study included 268 individuals: 134 patients aged ≥ 60 years with RA and 134 age- and sex-matched controls. Fat mass index (FMI), fat-free mass index (FFMI), and muscle mass were assessed by bioelectrical impedance analysis. Sarcopenia was defined using an EWGSOP2-aligned approach and osteoporosis according to WHO criteria. RC was defined as FFMI < 10th percentile and FMI > 25th percentile. Disability and nutritional risk were assessed using the Lawton-Brody IADL and MNA-SF.

Results: Compared with controls, patients with RA had lower BMI, FFMI, and FMI (all p ≤ 0.001), while visceral fat did not differ. Sarcopenia, osteoporosis, and osteosarcopenia were more prevalent in RA than in controls (49.3% vs. 20.9%, 53.0% vs. 32.1%, and 28.4% vs. 10.4%; all p < 0.001). Within RA, osteosarcopenia was associated with lower serum albumin and IADL scores and higher RC prevalence (39.5%). RC remained independently associated with osteosarcopenia after adjustment for demographic, comorbidity, and RA-specific factors (adjusted OR 10.43, 95% CI 3.13-34.79; p < 0.001).

Conclusions: Osteosarcopenia was more than twice as common in older patients with RA than in matched controls. Rheumatoid cachexia clustered within the osteosarcopenia subgroup and remained independently associated with osteosarcopenia. These findings support osteosarcopenia as a distinct catabolic phenotype in RA characterized by rheumatoid cachexia, lower serum albumin levels, and greater functional impairment.