Interrelationships among circulating interleukin-6, C-reactive protein, and traditional cardiovascular risk factors in women.

OBJECTIVE: Interleukin-6 (IL-6) and C-reactive protein (CRP) are markers of systemic vascular inflammation that herald atherothrombosis and may have important interrelationships with traditional cardiovascular risk factors. METHODS AND
RESULTS: We conducted a cross-sectional analysis among 340 apparently healthy women enrolled in the Women's Health Study. In unadjusted analyses, higher levels of IL-6 and CRP were seen with increasing body mass index (BMI), systolic and diastolic blood pressure, and smoking exposure. IL-6 levels were related to the frequency of alcohol intake (P=0.002) and showed an inverse relationship with exercise frequency and hormone replacement therapy (P<0.0001 for both). CRP levels increased with hormone replacement therapy (P=0.0002). Associations among IL-6, CRP, and lipid levels were minimal. Overall, mean levels of IL-6 and CRP increased with increasing numbers of clinical risk factors (P<0.0001). In multivariate analyses, independent relationships were seen between levels of IL-6 and age, BMI, smoking, systolic blood pressure, alcohol use, presence of diabetes, and frequency of exercise. CRP was associated with age, BMI, systolic blood pressure, high density lipoprotein, smoking, and hormone replacement therapy in adjusted analyses.
CONCLUSIONS: Plasma levels of IL-6 and CRP are independently related to several clinical cardiovascular risk factors in women.