Table 1 Participant characteristics
Variable | All participants (n = 102) | Rheumatoid arthritis (n = 51) | Matched controls (n = 51) |
|---|---|---|---|
Age (years) | 54.2 (12.5) | 54.8 (13.2) | 53.8 (11.9) |
BMI (kg/m2) | 30.0 (6.4) | 30.3 (7.5) | 29.6 (5.1) |
Waist circumference (cm) | 94.1 (15.2) | 94.9 (16.8) | 92.9 (13.3) |
Race | |||
 Caucasian | 74 (72.6%) | 36 (70.6%) | 38 (74.5%) |
 African American | 27 (26.5%) | 14 (27.5%) | 13 (25.5%) |
 Pacific Islander | 1 (1.0%) | 1 (2.0%) | 0 |
Gender | |||
 Female | 72 (70.6%) | 36 (70.6%) | 36 (70.6%) |
 Male | 30 (29.4%) | 15 (29.4%) | 15 (29.4%) |
Physical activity (kCal/day) | 557.1 (280.8) | 517.7 (279.4) | 609.1 (278.7) |
Physical activity (MET-hr/day) | 5.4 (2.6) | 4.9 (2.5) | 6.0 (2.5) |
Disease duration (months) | NA | 138.9 (136.3) | NA |
HAQ-disability index | 0.46 (0.6) | 0.68 (0.7)* | 0.00 (0.0) |
Comorbidity index | 1.2 (1.2) | 1.6 (1.1)* | 0.6 (0.9) |
DAS-28 mean (SD) | NA | 3.0 (1.4) | NA |
 Remission (DAS-28 < 2.6) |  | 19 (40%) |  |
 Low activity (DAS-28 2.6‒3.2) |  | 8 (17%) |  |
 Moderate activity (DAS-28 3.2‒5.1) |  | 16 (33%) |  |
 High activity (DAS-28 > 5.1) |  | 5 (10%) |  |
Rheumatoid factor positive | NA | 42/47 (89.4%) | NA |
Anti-cyclic citrullinated antibody positive | NA | 21/22 (95.6%) | NA |
Erosions present on radiographs | NA | 21/38 (55.2%) | NA |
Medication use | NA | Â | Â |
 Etanercept |  | 10 (19.6%) | NA |
 Infliximab |  | 2 (3.9%) | NA |
 Adalimumab |  | 5 (9.8%) | NA |
 Abatacept |  | 5 (9.8%) | NA |
 Methotrexate |  | 39 (76.5%) | NA |
 Leflunomide |  | 1 (2.0%) | NA |
 Sulfasalazine |  | 0 | NA |
 Hydroxychloroquine |  | 10 (19.6%) | NA |
 Nonsteroidal anti-inflammatory agents |  | 18 (35.3%)* | 1 (4.0%) |
 Prednisone (<5.0 mg/day) |  | 13 (25.5%) | NA |
Systemic inflammation | |||
 hsCRP (mg/L) | 3.0 (3.9) | 3.7 (4.9)* | 2.4 (2.9) |
 IL-1beta (pg/mL) | 0.23 (5.3) | 0.22 (4.1) | 0.17 (6.4) |
 IL-6 (pg/mL) | 4.9 (2.8) | 8.9 (2.9)* | 2.7 (1.6) |
 IL-8 (pg/mL) | 8.2 (2.1) | 8.9 (1.8) | 7.5 (2.3) |
 TNF-alpha (pg/mL) | 13.7 (2.3) | 19.9 (2.4)* | 9.5 (1.7) |
 IL-18 (pg/mL) | 408.3 (1.4) | 440.6 (1.3) | 379.3 (1.4) |
Adiposity and muscle tissue | |||
 Abdominal total adipose area (cm2) | 427.9 (181.0) | 408.4 (199.5) | 447.3 (160.2) |
 Abdominal subcutaneous adiposity (cm2) | 303.3 (143.7) | 304.5 (154.2) | 302.1 (133.9) |
 Abdominal visceral adiposity (cm2) | 124.6 (93.2) | 104.0 (77.1)* | 145.2 (103.6) |
 Abdominal liver density (Hu) | 59.0 (11.6) | 59.7 (10.6) | 58.2 (12.9) |
 Thigh total area (cm2) | 249.6 (65.4) | 248.8 (73.6) | 251.7 (57.1) |
 Thigh total adipose area (cm2) | 250.2 (66.0) | 134.3 (65.8) | 110.9 (68.0) |
 Thigh subcutaneous adiposity (cm2) | 122.6 (67.6) | 122.6 (62.7) | 113.8 (54.0) |
 Thigh inter-muscular adiposity (cm2) | 11.3 (7.4) | 11.7 (6.7) | 11.0 (8.1) |
 Thigh muscle area (cm2) | 119.6 (35.1) | 114.5 (37.1) | 125.4 (32.1) |
 Thigh muscle density (Hu) | 54.0 (8.1) | 50.7 (6.2) | 55.4 (6.8) |
Skeletal muscle inflammatory markers | |||
 IL-1β (pg/mL/mg) | 0.035 (0.084) | 0.037 (0.093) | 0.033 (0.069) |
 IL-6 (pg/mL/mg) | 0.012 (0.010) | 0.014 (0.010)* | 0.008 (0.007) |
 IL-8 (pg/mL/mg) | 0.139 (0.178) | 0.169 (0.211) | 0.097 (0.106) |
 TNF-α (pg/mL/mg) | 0.012 (0.015) | 0.014 (0.016) | 0.010 (0.014) |
 TLR4 (pg/mL/mg) | 0.891 (0.666) | 0.859 (0.692) | 0.937 (0.625) |