Stability of the factor structure of the metabolic syndrome across pubertal development: confirmatory factor analyses of three alternative models.

OBJECTIVE: To test the fit and stability of 3 alternative models of the metabolic syndrome's factor structure across 3 developmental stages. STUDY DESIGN: With data from the Fels Longitudinal Study, confirmatory factor analyses tested 3 alternative models of the factor structure underlying relationships among 8 metabolic syndrome-associated risks. Models tested were a 1-factor model (A), a 4-factor model (B), and a second-order latent factor model (C). Developmental stages assessed were prepuberty (ages 8-10), puberty (ages 11-15), and postpuberty (ages 16-20). RESULTS: Convergence was achieved for all developmental stages for model A, but the fit was poor throughout (root mean square error of approximation > 0.1). Standardized factor loadings for waist circumference and body mass index were much stronger than those for fasting insulin at all 3 time points. Although prepuberty and postpuberty models converged for models B and C, each model had problems with Heywood cases. The puberty model did not converge for either model B or C. CONCLUSIONS: The hypothetical structures commonly used to support the metabolic syndrome concept do not provide adequate fit in a pediatric sample and may be variable by maturation stage. A components-based approach to cardiovascular risk reduction, with emphasis on obesity prevention and control, may be a more appropriate clinical strategy for children and youth than a syndromic approach.

Patterns of change in cardiometabolic risk factors associated with the metabolic syndrome among children and adolescents: the Fels Longitudinal Study.

OBJECTIVES: To examine the patterns of change in cardiometabolic risk factors associated with the metabolic syndrome in children and adolescents between the ages of 8 to 19 years. STUDY DESIGN: Data of children and adolescents who participated in the Fels Longitudinal Study were analyzed. Body mass index, waist circumference, fasting insulin, fasting glucose, triglycerides, high-density lipoprotein cholesterol, systolic blood pressure, and diastolic blood pressure were assessed annually with a standardized protocol. RESULTS: The proportion of participants having at least 1 change between states of high and normal risk ranged from of 11.0% for body mass index to 30.4% for triglycerides. Youth in the high-risk category at baseline had a higher proportion having changed their status for all risk factors (all P < .05) except waist circumference compared with those in the normal-risk category. There were significant time effects for all risk factors (all P < .01) except fasting glucose and triglyceride levels in metric scores, but insignificant time effects for all risk factors in Z-scores in growth curve analyses. CONCLUSIONS: The cardiometabolic risk factors associated with the MetS were relatively stable among white children and adolescents in the normal risk category. Changes in status were common if the risk factor was elevated.

Predictive ability of childhood metabolic components for adult metabolic syndrome and type 2 diabetes.

OBJECTIVE: To estimate sensitivity, specificity, and positive and negative predictive values of components of the metabolic syndrome (MetS) during childhood for MetS and type 2 diabetes (T2D) in adulthood. STUDY DESIGN: Data from 3 major studies-the Fels Longitudinal Study, the Muscatine Study, and the Princeton Follow-up Study-were combined to examine how thresholds of metabolic components during childhood determine adult MetS and T2D. Available metabolic components examined in the 1789 subjects included high-density lipoprotein, triglyceride levels, glucose, and percentiles for body mass index, waist circumference, triglycerides, and systolic and diastolic blood pressures. Sensitivity, specificity, and positive and negative predictive values for a refined set of component threshold values were examined individually and in combination. RESULTS: Sensitivity and positive predictive values remained low for adult MetS and T2D for individual components. However, specificity and negative predictive values were fairly high for MetS and exceptionally so for T2D. In combination, having 1 or more of the components showed the highest sensitivity over any individual component and high negative predictive value. Overall, specificity and negative predictive values remained high whether considering individual or combined components for T2D. CONCLUSIONS: Sensitivity and positive predictive values on the basis of childhood measures remained relatively low, but specificity and negative predictive values were consistently higher, especially for T2D. This indicates that these components, when examined during childhood, may provide a useful screening approach to identifying children not at risk so that further attention can be focused on those who may be in need of future intervention.

Additive utility of family history and waist circumference to body mass index in childhood for predicting metabolic syndrome in adulthood.

OBJECTIVE: To determine whether waist circumference (WC) and family history of disease increase the predictive utility of body mass index (BMI) for adult metabolic syndrome (MetS). STUDY DESIGN: A subsample of 161 men and women from the Fels Longitudinal Study with childhood and adulthood measures were analyzed. Using logistic regression, childhood BMI categories (50th, 75th, and 85th percentiles), WC categories (75th and 90th percentiles), and family history of type 2 diabetes mellitus or cardiovascular disease were modeled separately and in combinations to predict adult MetS. Predicted probabilities and c-statistics were compared across models. RESULTS: The addition of family history to BMI improved the predicted probability of adult MetS from 29% to 52% (Deltac-statistic = 0.13). The combination of WC and BMI was more predictive than BMI alone but did not outperform the combination of family history and BMI. In 3 of the 4 models with a combination of family history, WC, and BMI, the predicted probability of adult MetS did not exceed that from the combination of family history and BMI. CONCLUSIONS: Family history of type 2 diabetes or cardiovascular disease is a useful addition to BMI in childhood to predict the future risk of adult MetS.

Prolonged juvenile States and delay of cardiovascular and metabolic risk factors: the Fels Longitudinal study.

OBJECTIVES: To ascertain the influence of such a prolonged juvenile state on delaying the onset of the metabolic syndrome, cardiovascular disease, and type 2 diabetes mellitus later in life. STUDY DESIGN: We define prolongation of a juvenile state as a retarded tempo of growth, determined by the timing of peak height velocity in each subject and relate the retarded tempo of growth to metabolic syndrome, cardiovascular disease, and type 2 diabetes mellitus later in life by use of serial data of 237 study participants (119 men and 118 women) enrolled in the Fels Longitudinal study. RESULTS: Children who matured early tended to have greater body mass index, waist circumference, and percent of body fat and were more likely to have adverse cardiovascular risk profiles than children who matured late. The differences in these risk factors between early and late maturers were significant for percent body fat, fasting plasma triglycerides, and fasting plasma insulin. CONCLUSIONS: The analyses disclosed a clear separation between early and late maturers in the appearance of these risk factors in young adulthood.

Childhood obesity predicts adult metabolic syndrome: the Fels Longitudinal Study.

OBJECTIVES: To determine the age of significant divergence in body mass index (BMI) and waist circumference in adults with and without the metabolic syndrome, and to provide age- and sex-specific childhood values that predict adult metabolic syndrome. STUDY DESIGN: Part 1 of this study is a retrospective cohort study of 92 men and 59 women (mean age, 51 years) who had metabolic syndrome and 154 randomly selected adults matched for age and sex who did not have the syndrome. Part 2 is a study of predictive accuracy in a validation sample of 743 participants. RESULTS: The first appearance of differences between adults with and without metabolic syndrome occurred at ages 8 and 13 for BMI and 6 and 13 for waist circumference in boys and girls, respectively. Odds ratios (ORs) for the metabolic syndrome at 30 years and older ranged from 1.4 to 1.9 across age groups in boys and from 0.8 to 2.8 across age groups in girls if BMI exceeded criterion values in childhood. The corresponding ORs for waist circumference ranged from 2.5 to 31.4 in boys and 1.7 to 2.5 in girls. These ORs increased with the number of examinations. CONCLUSIONS: Children with BMI and waist circumference values exceeding the established criterion values are at increased risk for the adult metabolic syndrome.