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Table 2 Skeletal muscle inflammatory marker correlations in patients with rheumatoid arthritis

From: Molecular alterations in skeletal muscle in rheumatoid arthritis are related to disease activity, physical inactivity, and disability

Variable Muscle IL-6 Muscle IL-8 Muscle TNF-α Muscle IL-1β Muscle TLR-4
Age (years) −0.07 0.05 0.09 −0.09 −0.29 *
BMI (kg/m2) 0.24 −0.05 −0.23 −0.10 −0.25
Disease activity (DAS28) 0.23 0.30 * 0.14 0.35 * −0.01
Disability (HAQ-DI) 0.33 * 0.19 0.09 0.33 * 0.12
Pain (VAS) 0.15 0.17 0.29 * 0.39 * 0.47 *
Prednisone use (yes = 1) 0.14 −0.05 0.00 0.01 −0.01
DMARD use (yes = 1) −0.04 −0.07 −0.30 0.21 0.08
Biologic use (yes = 1) −0.25 −0.37 * 0.21 −0.33 * 0.01
Comorbidity index 0.17 0.12 0.17 0.26 −0.08
Plasma hsCRP (mg/L) 0.20 0.07 0.11 −0.03 −0.17
Plasma IL-1β (pg/mL) 0.01 −0.07 −0.07 −0.14 −0.12
Plasma IL-6 (pg/mL) −0.03 0.11 0.12 −0.01 −0.10
Plasma IL-8 (pg/mL) −0.11 0.06 0.11 0.14 0.02
Plasma TNF-α (pg/mL) −0.37 * −0.15 0.02 −0.23 −0.08
Plasma IL-18 (pg/mL) −0.08 −0.12 −0.02 −0.24 0.06
GlycA (μmol/L) 0.41 * 0.38 * −0.06 0.07 −0.21
HOMA 0.11 0.04 −0.06 −0.10 −0.07
Insulin sensitivity (10-5.min-1/(pmol/L)) −0.20 −0.19 −0.06 −0.09 −0.18
Fasting insulin (mU/L) 0.13 0.09 −0.13 −0.06 −0.06
Visceral adiposity (cm2) 0.11 0.01 −0.28 0.03 −0.23
Abdominal subcutaneous adiposity (cm2) 0.21 0.06 −0.19 −0.06 −0.19
Total abdominal adiposity (cm2) 0.19 0.07 −0.24 −0.06 −0.28
Thigh muscle density (Hu) −0.04 −0.10 0.06 0.16 0.28 *
Thigh inter-muscular adiposity (cm2) 0.12 0.01 −0.08 −0.11 −0.12
Thigh subcutaneous adiposity (cm2) 0.31 * −0.07 −0.11 −0.09 −0.11
Exercise (min/day) −0.40 * −0.38 * −0.05 −0.38 * −0.11
Physical activity (MET h/day) −0.33 * −0.26 0.10 −0.35 * −0.15
  1. Data are shown as Spearman correlation coefficients. BMI body mass index, DAS-28 disease activity score with 28 joint count, HAQ-DI health assessment questionnaire disability index, VAS visual analog scale, DMARD disease-modifying anti-rheumatic drug (methotrexate, leflunomide, hydroxychlorquie), biologic biologic DMARD (adalimumab, etanercept, infliximab, abatacept), hsCRP high-sensitivity C-reactive protein, IL interleukin, TNF tumor necrosis factor, HOMA homeostasis model assessment, Hu Houndsfield units, MET metabolic equivalent, TLR toll-like receptor. * p < 0.05 for Spearman correlation