Obesity and clustering of cardiovascular disease risk factors are associated with elevated plasma complement C3 in children and adolescents

Objectives To investigate the relationship among obesity, cardiovascular disease risk factors (CVDRFs), and plasma complement C3 concentration in children and adolescents. Methods In a nationwide survey conducted between 1992 and 2000, all school children aged 618 yr with abnormal results in repeated urine samples, including hematuria, proteinuria, and glucosuria (n = 97 312; 36 557 boys and 60 755 girls), were investigated for their body mass index (BMI), blood pressure, fasting plasma glucose, total cholesterol, and plasma complement C3 concentrations. Results Children in the higher percentile groups for BMI or having more CVDRFs, namely, hypertension, diabetes, and hypercholesterolemia, had higher plasma C3 concentrations independently (p for both trends <0.05, adjusted for age and gender). The odds ratios (ORs) for having one, two, or three CVDRFs in obese children were 4.74 [95% confidence interval (CI) = 4.475.03], 19.8 (95% CI = 17.822.0), and 139 (95% CI = 96.6200), respectively, adjusted for age, gender, and family history of diabetes, which were substantially reduced after adjustment for plasma C3 concentrations. The ORs for children with plasma C3 concentrations in the highest quartile to have one, two, or three CVDRFs were 2.32 (95% CI = 2.212.44), 5.68 (95% CI = 4.836.67), and 58.6 (95% CI = 19.7174), respectively, adjusted for age, gender, family history of diabetes, and BMI. Conclusion Obesity is associated with clustering of CVDRFs in children and adolescents. Obesity and clustering of CVDRFs are associated with elevated plasma complement C3. Children and adolescents with higher plasma C3 concentrations have higher risk of clustering of CVDRFs independent of obesity.