Traditional cardiovascular risk factors such as central obesity, high blood pressure and insulin resistance, all constituents of metabolic syndrome, have been associated with increased levels of C-reactive protein (CRP). Therefore, this marker of low-grade inflammation may play a major role in the pathogenesis of cardiovascular diseases. In this study, data from a representative sample of urban adults was used to evaluate the association between CRP and metabolic syndrome, accounting for the type and number of its constituents.
Using random digit dialing, 1022 participants, aged 18-92 y, were selected. All participants completed a structured questionnaire comprising of information on social, demographic, behavioral and clinical aspects. Anthropometrics and blood pressure were recorded and a fasting blood sample collected. Metabolic syndrome was defined, according to the Third Report of the Expert Panel on Detection, Evaluation and Treatment of High Blood Cholesterol in Adults, as the presence of three or more of the following characteristics: waist circumference greater than 102 cm in men and 88 cm in women; triglyceride levels > or = 150 mg/dl; high-density lipoprotein cholesterol levels < 40 mg/dl in men and < 50 mg/dl in women; blood pressure > or = 130/85 mm Hg; and serum glucose > or = 110 mg/dl. High-sensitivity CRP was assessed by immunonephelometric assay. After excluding 65 participants with CRP > or = 10 mg/l, 957 subjects (599 women and 358 men) remained for analysis. Geometric means were compared after adjustment for age, sex, alcohol consumption and smoking.
Higher mean levels of CRP (2.34 vs 1.36, P < 0.001) were observed when metabolic syndrome was present. Also, mean CRP levels were significantly higher in the presence of central obesity (2.45 vs 1.24, P < 0.001), high blood pressure (1.76 vs 1.12, P < 0.001), hypertriglyceridemia (2.17 vs 1.32, P < 0.001) and high fasting glucose (1.96 vs 1.46, P = 0.032). We found a significant increasing trend (P < 0.001) in mean levels of CRP as the number of features of metabolic syndrome increased. The major contributing features for high CRP levels were central obesity and high blood pressure.
Present data show that increasing severity of metabolic syndrome is associated with increasing CRP. Additionally, we found that central obesity and high blood pressure are the most important determinants of the low-grade chronic inflammation present in metabolic syndrome.