Abdominal adiposity in rheumatoid arthritis: association with cardiometabolic risk factors and disease characteristics

Abstract

Objective: Abdominal adiposity, especially visceral adiposity, is emerging as a recognized cardiometabolic risk factor. This study was undertaken to investigate how abdominal fat is distributed in rheumatoid arthritis (RA), and its RA-related determinants.

Methods: Men and women with RA were compared with non-RA controls from the Multi-Ethnic Study of Atherosclerosis. Participants underwent anthropometric studies and quantification of visceral and subcutaneous fat areas (VFA and SFA) using abdominal computed tomography.

Results: A total of 131 RA patients were compared with 121 controls. Despite similar body mass index and waist circumference between the RA and control groups, the adjusted mean VFA was 45 cm2 higher (+51%) in male RA patients versus male controls (P = 0.005), but did not significantly differ by RA status in women. The adjusted mean SFA was 119 cm2 higher (+68%) in female RA patients versus female controls (P < 0.001), but did not significantly differ by RA status in men. Elevated VFA (≥75th percentile) was associated with a significantly higher adjusted probability of having an elevated fasting glucose level, hypertension, or meeting the composite definition of the metabolic syndrome in the RA group compared with controls. Within the RA group, rheumatoid factor seropositivity and higher cumulative prednisone exposure were significantly associated with a higher mean adjusted VFA. Higher C-reactive protein levels and lower Sharp/van der Heijde scores were significantly associated with both VFA and SFA.

Conclusion: The distribution of abdominal fat differs significantly by RA status. Higher VFA in men with RA, and the more potent association of VFA with cardiometabolic risk factors in men and women with RA, may contribute to cardiovascular risk in RA populations.

Figure 1. Crude and Adjusted Associations of RA Status with Abdominal Computed Tomography-Derived Adiposity Measures

Graphs depict the crude and adjusted means (in cm²) and 95% confidence intervals for measures of A) total abdominal fat area; B) visceral fat area; and C) subcutaneous fat area according to RA status and gender. Analyses were adjusted for age, ethnicity, education, exercise, hours of television watching, depression, current and former smoking, thyroid disease, and use of hormone replacement therapy (female subgroup only)

Figure 2. Adjusted Associations of Quartiles of Visceral Fat Area with Components of the Metabolic Syndrome: RA vs. Control

Graphs depict the adjusted probabilities and the associated 95% confidence intervals for meeting the ATPIII metabolic syndrome definitions associated with quartiles of visceral fat area according to RA status for the outcomes of A) elevated fasting glucose (>100 mg/dL); B) elevated blood pressure (≥ 130/85 mm Hg); C) Low HDL cholesterol (< 50 mg/dL for men or < 40 mg/dL for women); D) Fulfilling 3 or more of the 5 metabolic syndrome criteria. Analyses were adjusted for age, ethnicity, education, exercise, hours of television watching, depression, current and former smoking, thyroid disease, and use of antihypertensive, antidiabetic, and lipid lowering medications.

Figure 3. Adjusted Combined Associations of Rheumatoid Factor Status and Cumulative Prednisone with Visceral Fat Area

Graphs depict the adjusted mean visceral fat areas (in cm²) and the associated 95% confidence intervals for RA patients divided into mutually exclusive subgroups based on seropositivity for rheumatoid factor and cumulative glucocorticoid exposure (dichotomized above and below 9 grams of prior exposure). Analyses were adjusted for age, ethnicity, education, exercise, hours of television watching, depression, current and former smoking, thyroid disease, C-reactive protein, and total Sharp van der Heijde score.