Waist circumference is related to low-grade inflammation in youth

Objectives. To examine markers of inflammation in 9- and 15-year-olds with high waist circumference and compare these with controls, and to examine the relationships between inflammatory markers and cardiovascular disease (CVD) risk factors. Methods. Cross-sectional analysis of data from 2 299 Norwegian 9- and 15-year-olds participating in the "Physical activity among Norwegian Children Study". In each sex and age group, the 10 participants with the highest waist circumference (HW) were selected (n = 40) for analyses, and a random sample of 40 participants within the same groups were included as controls. Inflammatory markers included C-reactive protein (CRP), leptin, adiponectin, plasminogen activator inhibitor-1 (PAI-1), tumor necrosis factor-alpha (TNF-alpha), hepatocyte growth factor (HGF), resistin and interleukin-6 (IL-6). The CVD risk factors included blood pressure, glucose, insulin, triglycerides and high density lipoprotein cholesterol. Results. HW participants had elevated levels of CRP (mean difference 1.50 mg/l; 95% confidence interval [CI] 0.33 to 2.66), PAI-1 (mean difference 13.3 ng/ml; 95% CI 4.1 to 22.5) and HGF (mean difference 0.29 ng/ml; 95% CI 0.07 to 0.51) compared with controls. All CVD risk factors differed between the HW group and controls. The CVD risk factors were not associated with TNF alpha or IL-6, but CRP, HGF and PAI-1 were related to the metabolic risk score. Conclusions. Low grade systemic inflammation is already present in youth with high waist circumference. CRP, HGF and PAI-1 may be related to the adverse overall metabolic risk profile observed in these children and adolescents.