Research Article

Marked Independent Relationship between Circulating Interleukin-6 Concentrations and Endothelial Activation in Rheumatoid Arthritis

Table 1

Clinical characteristics and endothelial activation molecule and resistin concentrations in black and white patients with RA.

CharacteristicsBlack ( )White ( )

Age, yrs55.8 (10.2)58.2 (10.9)0.1
Female sex89.379.10.04
Conventional  cardiovascular  risk  factors
Smoking
 Current3.69.60.09
 Ever 50.012.5<0.0001
 BMI, kg/m229.5 (6.6)25.7 (4.7)<0.0001
 Waist circumference, cm93.6 (13.5)89.4 (13.5)0.02
 Waist-hip ratio0.85 (0.80–89.5)0.87 (0.81–0.93)0.05
 Hypertension 74.149.50.0002
 SBP, mmHg140 (25)130 (17)0.0007
 DBP, mmHg86 (15)80 (9)0.0001
 Chol, mmol/L4.6 (0.9)5.0 (1.1)0.005
 HDL chol, mmol/L1.50 (1.30–1.80)1.59 (1.30–1.99)0.09
 LDL chol, mmol/L2.5 (0.8)2.8 (0.9)0.02
 Triglycerides, mmol/L1.0 (0.7–1.39)1.0 (0.8–1.4)0.7
 Non-HDL chol, mmol/L3.1 (0.9)3.3 (1.0)0.07
 Chol-HDL chol ratio3.2 (1.0)3.2 (1.0)0.9
 Chol-HDL chol ratio > 420.216.50.5
 Diabetes17.07.60.04
 Glucose, mmol/L4.9 (4.5–5.4)4.7 (4.4–5.0)0.03
 EGFR, mL/min104 (91–126)89 (75–103)<0.0001
Cardiovascular drugs
 Antihypertensive agents55.443.80.09
 Statins20.537.10.007
 Ezetimibe0.013.4
 Oral glucose lowering agents35.221.40.02
 Insulin 0.91.90.5
RA characteristics
 Disease duration, yrs13.0 (9.3)14.5 (9.4)0.3
 Rheumatoid factor positive76.878.90.8
 Deformed joints, 88 (3–15) 4 (0–17)0.04
 DAS284.2 (1.3)3.7 (1.6)0.8
 ESR, mm/hr21 (9–39)7 (3–15)<0.0001
 CRP, mg/L7.0 (4.0–15.0) 4.0 (1.5–12.1)0.003
 IL-6, pg/mL3.9 (2.5–6.3)3.2 (2.0–5.8)0.003
 Prednisone use1.82.90.6
Endothelial activation molecules
 MCP-1, pg/mL349.32 (224.76–665.07)472.01 (331.91–683.47)0.006
 VCAM-1, ng/mL841.84 (696.33–1071.75)822.09 (638.55–1028.57)0.4
 ICAM-1, ng/mL238.10 (170.93–314.52)309.19 (252.09–383.97)<0.0001
 E-selectin, ng/mL42.23 (19.78)35.51 (16.53)0.7
 Resistin, ng/mL37.82 (24.00–56.32)32.00 (21.62–50.30)0.2

Dichotomous variables are expressed as proportions or percentages and continuous characteristics as mean (SD) or median (interquartile range). Significant differences are shown in bold. Yrs: years; BMI: body mass index; SBP: systolic blood pressure; DBP: Diastolic blood pressure; chol: cholesterol; HDL: high-density lipoprotein; LDL: low-density lipoprotein, EGFR: estimated glomerular filtration rate; N: Number of; DAS28: disease activity score in 28 joints; ESR: erythrocyte sedimentation rate; CRP: C-reactive protein; IL-6: interleukin-6; MCP-1: monocyte chemoattractant protein-1; VCAM-1: vascular adhesion molecule-1; ICAM-1: intercellular adhesion molecule-1. DAS28 reflects moderately active disease in both black and white patients.