Malnutrition and sarcopenia in rheumatoid arthritis: prevalence, risk factors, and the limitations of body mass index: a cross-sectional study.
BACKGROUND & AIMS Malnutrition and sarcopenia are increasingly recognized as important but frequently underdiagnosed comorbidities in patients with rheumatoid arthritis (RA). However, data based on contemporary diagnostic criteria and dual-energy X-ray absorptiometry (DXA)-derived body composition remain limited. This study investigated the prevalence and independent factors associated with malnutrition and sarcopenia in patients with RA. METHODS This cross-sectional study included 79 patients with RA (81% women, mean age 66 ± 8 years). Assessment included DXA, bioelectrical impedance analysis (BIA), handgrip strength, and assessment of physical activity using the International Physical Activity Questionnaire - Short Form (IPAQ-SF). Malnutrition was diagnosed according to Global Leadership Initiative on Malnutrition (GLIM) criteria and sarcopenia according to European Working Group on Sarcopenia in Older People (EWGSOP2) criteria. Univariable and multivariable logistic regression analyses were performed to identify independent factors. RESULTS Malnutrition and sarcopenia were identified in 41.8% and 24.1% of participants, respectively. Only 7 participants (8.9%) met the GLIM low body mass index (BMI) criterion, whereas reduced fat-free mass index (FFMI) was identified in 33 (41.8%). Among participants with normal BMI, 68.4% had reduced FFMI, indicating that BMI alone underestimated altered body composition. Participants with malnutrition had lower appendicular skeletal muscle mass index (ASMI) (5.83 vs. 7.67 kg/m2), phase angle (4.18 vs. 4.81°), and handgrip strength (17.8 vs. 24.8 kg) (all p ≤ 0.002). Low ASMI was observed in 13 participants (16.5%), while 24 (30.4%) had low handgrip strength. In multivariable analyses, female sex (adjusted OR 8.31, 95% CI 1.49-46.40) and glucocorticoid therapy (adjusted OR 4.72, 95% CI 1.05-21.24) were independently associated with malnutrition. Older age (adjusted OR 1.16 per year, 95% CI 1.05-1.28) and low physical activity (adjusted OR 5.30, 95% CI 1.35-20.75) were independently associated with sarcopenia. CONCLUSIONS Malnutrition and sarcopenia are common in patients with RA and frequently remain undetected when nutritional assessment relies solely on BMI. Routine assessment using validated diagnostic criteria together with body composition analysis may improve identification of at-risk patients. Particular attention should be paid to women, older adults, physically inactive patients, and those receiving glucocorticoid therapy, who may benefit most from early nutritional and exercise-based interventions.