Age-belated patterns of the clustering of cardiovascular risk variables ofSyndrome X from childhood to young adulthood in a population made up of black and white subjects - The Bogalusa Heart Study

The age-related patterns of clustering of cardiovascular risk variables of Syndrome X from childhood to adulthood were examined in a community-based s ample of black and white children (aged 5-10 years, n = 2,389), adolescents (aged 11-17 Sears, n = 3,371), and young adults (aged 18-37 years, n = 2,1 15). In the analysis of clustering, insulin resistance index, BMI, triglyce rides/ HDL cholesterol ratio, and mean arterial pressure were used either a s categorical variables (age-, race- and sex-specific values >75th percenti les) to calculate risk ratios (observed frequency/expected frequency) or as continuous variables (normal scores based on ranks) to compute intraclass correlations. In the total sample, the risk ratio for clustering of adverse levels of all 4 variables was 9.8 for whites (P < 0.01) versus 7.4 for bla cks (P < 0.01); the intraclass correlation was 0.33 for whites (P < 0.001) versus 0.26 for blacks (P < 0.001). Both the risk ratio and intraclass corr elation were significantly higher in whites than in blacks in the total sam ple. The intraclass correlations of the 3: variables were significant (P < 0.001) in all race and age-groups, and they were higher during preadolescen ce and adulthood than during adolescence. Furthermore, unlike risk ratios, intraclass correlations showed a continuous increase with age during adulth ood. When BMI was adjusted, the intraclass correlations involving the other 3 variables were reduced by similar to 50%, and the age-related pattern ma s no longer evident. These results suggest that the degree of clustering of risk variables of Syndrome X varies with age from childhood to adulthood a nd is likely influenced by the age-related changes in obesity and the atten dant insulin resistance.