Non-obese visceral adiposity is associated with the risk of atherosclerosis in Japanese patients with rheumatoid arthritis: a cross-sectional study

Rheumatoid arthritis (RA) patients often have altered body composition including reduced muscle mass and increased fat mass. Some RA patients are likely to increase visceral fat without obesity [Body Mass Index (BMI) ≥ 25]. The objective of the study was to determine the association between obesity and/or visceral adiposity and the risk for atherosclerosis in Japanese RA patients. Obesity was evaluated using the BMI, with visceral adiposity evaluated using the visceral fat area (VFA) and the visceral/subcutaneous fat ratio (V/S ratio), quantified using the dual bioelectrical impedance method. Atherosclerosis was evaluated based on the intima–media thickness (IMT) and Plaque score (PS) of the carotid artery, measured using ultrasonography. Multivariate analysis was performed to determine the factors associated with IMT and PS. IMT and PS were compared among groups of patients sub-classified according to BMI and VFA levels. The V/S ratio was higher in RA patients than healthy controls, after adjustment for age, BMI, and waist circumference. On multivariate analysis, the V/S ratio, but not the BMI, was independently associated with the IMT and PS. Among the sub-classifications for BMI and VFA, non-obese patients with a high visceral adiposity (18.5 ≤ BMI < 25 kg/m² and VFA ≥ 100 cm²) had the highest IMT (mean IMT, 0.93 ± 0.29 mm; maximum IMT, 1.44 ± 0.71 mm) and PS (1.43 ± 0.61), compared to all other BMI and VFA subgroups. RA patients have increased visceral adiposity, which is associated with a high prevalence of atherosclerotic of plaques. Non-obese RA patients who have visceral adiposity have a specifically higher risk for atherosclerosis.