Obesity and clustering of cardiovascular disease risk factors are associated with elevated plasma complement C 3 in children and adolescents

Objectives To investigate the relationship among obesity, cardiovascular disease risk factors ( CVDRF s), and plasma complement C 3 concentration in children and adolescents. Methods In a nationwide survey conducted between 1992 and 2000, all school children aged 6–18 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 C 3 concentrations. Results Children in the higher percentile groups for BMI or having more CVDRF s, namely, hypertension, diabetes, and hypercholesterolemia, had higher plasma C 3 concentrations independently (p for both trends <0.05, adjusted for age and gender). The odds ratios ( OR s) for having one, two, or three CVDRF s in obese children were 4.74 [95% confidence interval ( CI ) = 4.47–5.03], 19.8 (95% CI = 17.8–22.0), and 139 (95% CI = 96.6–200), respectively, adjusted for age, gender, and family history of diabetes, which were substantially reduced after adjustment for plasma C 3 concentrations. The OR s for children with plasma C 3 concentrations in the highest quartile to have one, two, or three CVDRF s were 2.32 (95% CI = 2.21–2.44), 5.68 (95% CI = 4.83–6.67), and 58.6 (95% CI = 19.7–174), respectively, adjusted for age, gender, family history of diabetes, and BMI . Conclusion Obesity is associated with clustering of CVDRF s in children and adolescents. Obesity and clustering of CVDRF s are associated with elevated plasma complement C 3. Children and adolescents with higher plasma C 3 concentrations have higher risk of clustering of CVDRF s independent of obesity.