Factors Associated with Low Lean Mass in Early Rheumatoid Arthritis: A Cross-Sectional Study

Background and Objectives: The aim of the study was to evaluate body composition (BC) of rheumatoid arthritis (RA) patients at disease onset compared to population controls focusing on the associations between low lean mass and disease specific parameters, nutritional factors and physical activity. Materials and Methods: 91 patients with early rheumatoid arthritis (ERA) (72% female) and 328 control subjects (54% female) were studied. BC-lean and fat mass parameters were measured with a Lunar Prodigy Dual Energy X-Ray Absorptiometry (DXA) machine. The prevalence, age and gender adjusted odds ratios of having low lean mass and overfat, associations between nutrition, physical activity, and ERA disease specific parameters and the presence of low lean mass were evaluated. Results: We found that the BC of patients with recent onset RA differs from control subjects—ERA patients had a higher mean body fat percentage (BFP) and lower appendicular lean mass (ALM). 41.8% of the ERA patients and 19.8% of the controls were classified as having low lean mass adjusted OR 3.3 (95% C.I. 1.9–5.5, p < 0.001). 68.1% of the ERA subjects and 47.3% of the controls were overfat (adjusted OR 1.9 (95% C.I. 1.1–3.3, p = 0.02)) and the adjusted odds of having both low lean mass and overfat were 4.4 times higher (26.4% vs. 7.0% 95% C.I. 2.3–8.4, p < 0.001) among the ERA group. Higher ESR (OR 1.03, C.I. 1.002–1.051, p = 0.03), CRP (OR 1.03, C.I. 1.002–1.061, p = 0.04), lower protein intake (OR 0.98 C.I. 0.96–0.99, p = 0.04), corticosteroid usage (OR 3.71 C.I. 1.4–9.9, p < 0.01) and lower quality of life (higher HAQ score OR 2.41 C.I. 1.24–4.65, p < 0.01) were associated with having low lean mass in the ERA group (adjusted to age and gender). Conclusions: Patients with early RA have lower appendicular lean mass and higher body fat percentage compared to healthy controls. Loss of lean mass in early RA is associated with elevated inflammatory markers inducing catabolism, lower protein intake and also with GCS treatment.