Humoral predictors of ankle-brachial index in patients with peripheral arterial disease and controls

Peripheral arterial disease (PAD) is a common condition due to atherosclerosis with high prevalence in population over 55 years. Although its pathophysiology is well recognized, the role of inflammatory markers is still not fully known. The aim of the study was to assess the relation of C-reactive protein (CRP), tumor necrosis factors-alpha (TNF-alpha) and interleukin-6 (IL-6) to ankle-brachial index (ABI) and metabolic variables in patients with PAD. The second aim was to find the most significant humoral predictor of ABI. The study groups consisted of 55 patients (36 men and 19 women) diagnosed with PAD (age 63.65 ± 6.11 years) and 34 control subjects (7 men, 27 women) of average age 59.88 ± 6.10 years with ABI > 0.9. Blood samples were analyzed for glycaemia, lipid profile and inflammatory markers (CRP, TNF-alpha and IL-6). A significantly higher serum total cholesterol (p = 0.04), triglycerides (p = 0.005) and lower HDL cholesterol (p < 0.0001) were found in the PAD group as compared to controls. Patients with PAD had significantly higher serum glucose (p = 0.008), CRP (p = 0.0044), IL-6 (p < 0.0001) and TNF-α (p < 0.0001) in comparison to controls. In a multiple linear regression analysis among variables log IL-6 and log HDL cholesterol were most significantly related to ABI (LW 4.75 for log IL-6, LW 4.016 for log HDL cholesterol, respectively, p < 0.01) in all subjects. We conclude that among traditional and humoral risk factors IL-6 is the strongest predictor of ABI. HDL cholesterol is also significant and strong predictor of decreased ABI and could be a potential biomarker of PAD in patients using lipid lowering drugs (Tab. 1, Ref. 31).