Relationship between Body Mass Index and Metabolic Syndrome Risk Factors among US 8- to 14-Year-Olds, 1999 to 2002

Article Outline

• Abstract
• Methods
  • Eligibility Criteria
  • Fasting Glucose
  • Systolic and Diastolic Blood Pressure
  • Triglyceride
  • HDL Cholesterol
  • Waist Circumference
  • Body Mass Index
• Results
• Discussion
• Acknowledgment
• References
• Copyright

Objectives

To determine the prevalence of metabolic syndrome risk factors (MSRF) and examine the relationship between body mass index and the prevalence of ≥3 MSRF in 8- to 11- and 12- to 14-year-old age groups.

Study design

Combined 1999 to 2002 National Health and Nutrition Examination Survey data were analyzed (N = 1698). Prevalence of normal weight, at-risk for overweight, and overweight were determined. Prevalence of ≥3 MSRF (abnormal waist circumference, glucose, HDL cholesterol, triglyceride, systolic and diastolic blood pressure) were reported using (1) an age, sex, and ethnicity-adjusted and (2) a crude profile (no adjustments).

Results

Among overweight 8- to 11-year-old children, 6.5% (95% CI, 3.82 to 10.86) had ≥3 MSRF using the crude profile and 9.51% (95% CI 5.59 to 15.71) using the adjusted profile. Among overweight 12- to 14-year-olds, 43.76% (95% CI, 33.27 to 54.85) had ≥3 MSRF using the crude profile and 26.28% (95% CI, 16.71 to 38.78) using the adjusted profile.

Conclusions

A substantial number of overweight 8- to 14-year-olds have ≥3 MSRF, indicating that overweight in early adolescence may put children at risk for adult-onset cardiovascular disease and/or type 2 diabetes well before they become teenagers.

Abbreviations: BMI, Body mass index, MSRF, Metabolic syndrome risk factors, NHANES, National Health and Nutrition Examination Survey

More than 17% of children in the United States ages 2 to 19 are presently overweight, and another 16% are at-risk for becoming overweight.¹, ², ³ Because childhood-onset overweight can be a precursor to such chronic conditions as diabetes, cardiovascular disease, hypertension, stroke, osteoarthritis, and certain cancers⁴, ⁵, ⁶ and is becoming more prevalent at increasingly younger ages, it has become a public health priority. There are concerns that childhood overweight will contribute to an earlier onset of overall morbidity and mortality in adulthood.⁷

Recent studies have reported an association between overweight in adolescence and the subsequent development of a constellation of cardiometabolic risk factors characterized by insulin resistance, dyslipidemia, and hypertension, which some have termed the “metabolic syndrome.”⁸ In turn, this constellation is associated with type 2 diabetes and long-term vascular complications in both childhood and adulthood.⁷, ⁸, ⁹, ¹⁰, ¹¹, ¹², ¹³ Little is known, however, about the prevalence of metabolic syndrome risk factors (MSRF) in population-based studies in younger adolescents and among 8- to 11-year-olds in particular; yet this is an important demographic, given the overweight epidemic in increasingly younger ages in this country.¹

The objectives of this analysis were 2-fold: (1) To determine the prevalence of MSRF (using 1 crude and 1 age-, ethnicity-, and sex-adjusted profile) among a national sample of children among 2 specific age groups, 8- to 11-year-olds and 12- to 14-year-olds; and (2) to examine the relationship between body mass index (BMI) and the prevalence and distribution of ≥3 MSRF the same age groups.

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Methods 

With the release of National Health and Nutrition Examination Survey (NHANES) 1999 to 2000 and NHANES 2001-2002 data, the National Center for Health Statistics (NCHS) recommended that the time period from 1999 to 2002 be considered as 1 survey to produce estimates with greater statistical reliability. Therefore, for this study, NHANES data files for 1999 to 2000 and 2001 to 2002 were combined to form a single analytic file. Both the NHANES 1999 to 2000 and 2001 to 2002 surveys used a stratified, multistage probability design to capture a representative sample of the civilian noninstitutionalized US population.

Eligibility Criteria 

We selected all Mexican American, non-Hispanic white, and non-Hispanic black boys and girls ages 8 to 14 years from the combined 1999 to 2000 and 2001 to 2002 NHANES data. We excluded all those who identified as “other.” Two groups, younger (ages 8 to 11) and older adolescents (ages 12 to 14), were formed for the analysis. We selected 8- to 11-year-old subjects who had the following variables available for analysis: waist circumference, BMI, HDL cholesterol, and systolic and diastolic blood pressure. For 12- to 14-year-old subjects, in addition to the above listed variables for the 8- to 11-year-olds, we included fasting glucose and triglyceride variables for the analysis. Because we chose to only analyze those who had data available on all of the CVD risk factors collected for their age group, the sample size was reduced from a total sample size of 3455 to 1698.

Children were excluded from the analysis if they were known to have diabetes (n = 26) or used medications that altered blood pressure, lipid metabolism, or blood glucose such as insulin, androgens, anabolic steroids, or adrenal corticosteroids (n = 30). No children were pregnant.We created 2 MSRF profiles to compare in our analysis: (1) a crude profile similar to that used in the NHANES III analysis¹⁴ that included nonadjusted single cutoff points to define elevated blood lipids, waist circumference, and blood glucose, and (2) an age, sex, and ethnicity-adjusted profile. All individual component threshold values were based on national standardized norms and are comparable to those reported by others¹⁵, ¹⁶, ¹⁷ and are described in summary in Table I and in detail below.

Table I. Adult and pediatric threshold values of cardiovascular disease risk factors

The criteria used to estimate the prevalence of MSRF using an age-, sex- and ethnic-adjusted profile among 8- to 14-year-olds were modified from those of the National Cholesterol Education Program's Adult Treatment Panel (ATP III) metabolic syndrome definition for adults (Table I). The threshold values used in this study to define each MSRF for each profile are described below and in Table II.

Table II. NHANES III²⁷, ²⁸ threshold values for adjusted profile

Age in years
	8	9	10	11	12	13	14
Waist circumference (75th percentile)
Boys
Mexican American	66.2	68.9	71.6	74.4	77.1	79.8	82.6
Non-Hispanic white	64.3	67.0	69.6	72.2	74.9	77.5	80.1
Non-Hispanic black	61.7	63.9	66.1	68.3	70.5	72.7	74.9
Girls
Mexican American	65.6	68.2	70.8	73.4	76.0	78.6	81.2
Non-Hispanic white	63.4	65.7	68.0	70.3	72.6	74.9	77.2
Non-Hispanic black	64.7	67.5	70.3	73.1	75.9	78.8	81.6
HDL cholesterol (10th percentile)
Boys and girls
Mexican American	38	37	37	37	35	35	35
Non-Hispanic white	36	38	38	38	35	35	35
Non-Hispanic black	42	42	42	42	39	39	39
Triglyceride (90th percentile)
Mexican American					144	144	144
Non-Hispanic white					168	168	168
Non-Hispanic black					103	103	103

Fasting Glucose 

On the basis of the American Diabetes Association criteria, a fasting glucose level of 100 mg/dL or higher was considered to be abnormal for both the crude and adjusted profiles.¹⁸ Fasting (≥8 hours but <24 hours) glucose data were available for 12- to 14-year-olds only, and the appropriate fasting glucose-specific, 4-year weights were applied. The purpose of weighting the NHANES sample data is to permit the analysis of estimates that would have been obtained if the entire sampling frame had been surveyed. Weighting takes into account several features of the surveys: the specific probabilities of selection for the individual domains that were oversampled (in both the 1999 to 2000 and 2001 to 2002 surveys, Mexican Americans and blacks were oversampled), as well as nonresponse and differences between the sample and the total population. When analyzing the combined 4-year data set, the correct sampling weights must be used to produce unbiased estimates. In terms of fasting glucose specifically, appropriate sample weights have been calculated to reflect both the additional stage of sampling and the additional nonresponse (if any) for the subsample. These weights differ from the full examination weight and the revised weights were used for statistical estimation.

Systolic and Diastolic Blood Pressure 

To define crude and adjusted threshold values of normal systolic and diastolic blood pressure adjusted for sex and age, we used the 90th percentile values. These values are proposed by the Update on the Task Force for High Blood Pressure in Children and Adolescents (a working group on hypertension control in children and adolescents from the National High Blood Pressure Education Program¹⁹). Blood pressure was considered to be abnormal if systolic and/or diastolic values were abnormal.

Triglyceride 

The 90th percentile values adjusted for sex and ethnicity (non-Hispanic black, non-Hispanic white, and Mexican American) from the NHANES III (1988 to 1994) findings in 12- to 14-year-olds were used for the adjusted profile.²⁰ Similar to previous studies, 1 normal-abnormal triglyceride cutoff value of ≥110 mg/dL was used as the cutoff for the crude profile.¹⁴ Triglyceride values are not available for children younger than 12 in the NHANES and were therefore not included in the analysis in this age group.

HDL Cholesterol 

The adjusted profile HDL cholesterol threshold values were the 10th percentiles adjusted for age and race (non-Hispanic black, non-Hispanic white, and Mexican American) from the NHANES III (1988 to 1994) data.²⁰ For the crude profile, an HDL cholesterol value of ≤40 mg/dL was considered abnormal.¹⁴

Waist Circumference 

The adjusted profile used the 75th percentile threshold value for waist circumference based on data from the NHANES III, adjusted for age, sex, and ethnicity.²¹ We used this cutoff percentile to be consistent with (1) the well-accepted adult criteria of MSRF⁷ and (2) a previous pediatric study of the NHANES¹⁵ and (3) to provide some contrast to the crude profile. Additionally, because this analysis included young adolescents, we chose a conservative percentile for this profile to be as sensitive as possible and therefore identify all children who may be at the earliest stages of chronic disease development. Similar to the NHANES III analysis,¹⁴ the crude profile used the 90th percentile of this sample as the abnormal threshold values.

Body Mass Index 

We used Centers for Disease Control and Prevention (CDC) weight classifications for youth using BMI [defined as weight (kg)/height (m)²]³⁵ percentiles ranges: underweight (≤5th), normal weight (≥5th to ≤85th), at risk for overweight (≥85th to ≤95th), and overweight (≥95th). As in adults, BMI is an imperfect indicator of adiposity in children. However, because BMI is nonlinear in children, BMI percentiles and not absolute and BMI cutoffs must be used to evaluate weight.²²NHANES-selected persons were invited to take part in the survey by being interviewed in their homes. Household interview data were collected with Computer Assisted Personal Interviewing (CAPI) procedures and included demographic, socioeconomic, dietary, and health-related information. After the interview, participants were asked to undergo a physical exam at a Medical Examination Center (MEC).

All laboratory methods used at the MEC are reported in detail in The NHANES Laboratory/Medical Technologists Procedures Manual.²³ Briefly, the standardized examination anthropometric measures consisted of barefoot standing height (with a stadiometer), weight with minimal clothing (on a digital, electronic scale), and waist circumference (in the horizontal plane at a point marked just above the right ilium on the mid-axillary line, at minimal respiration).²³ Heights and circumferences were recorded to the nearest 0.1 cm.

All blood samples were collected, processed, stored at −20°C, and shipped to the laboratory for analysis.²⁴ HDL was measured in supernatants after precipitation of apo B–containing lipoproteins with heparin-manganese chloride and removal of excess manganese by precipitation with sodium bicarbonate.²⁴, ²⁵ Triglycerides were analyzed enzymatically with the use of commercially available reagents. Fasting plasma glucose was measured by a modified hexokinase enzymatic method.²⁶

The NHANES surveys are based on a complex multistage sampling scheme. According to CDC guidelines, the sampling scheme, as well as sampling weights, must be accommodated by the software used to analyze the data in order to obtain valid results. Therefore, SUDAAN (interfaced with SAS v. 9.0, SAS Institute) was used to obtain accurate point estimates with appropriate variance estimates.

The prevalence of each MSRF for both age groups was estimated, and precision was indicated with 95% confidence intervals. The national prevalence of ≥3 abnormal MSRF was calculated and appropriate weights were applied to generate national population estimates.

Among the 8- to 11-year-olds, systolic blood pressure, diastolic blood pressure, waist circumference, and HDL cholesterol combinations were examined. Fasting blood glucose was only available e in 12- to 14-year-olds. Triglycerides were only measured in a subsample of the entire group, and appropriate weights are not available for 8- to 11-year-olds, thus they could not be included in the overall number of MSRF present in the younger age group.

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Results 

Distribution of demographic characteristics and CDC BMI percentile groups are presented in Table III. The total unweighted sample size of the combined 1999 to 2000 and 2001 to 2002 NHANES data sets for children ages 8 through 14 years old was 1698 (weighted N = 20497949). In general, the analysis shows similar rates of overweight in both age groups; about 17.50% and 17% for both boys and girls, respectively. Overall, almost 25% of non-Hispanic black and 22% of Mexican American and almost 15% of non-Hispanic white 8- to 11-year-olds were overweight. Similarly, among the older age group, almost 27% of Mexican Americans were overweight, followed by 22% of non-Hispanic blacks and almost 15% of non-Hispanic whites.

Table III. Demographic Distribution of NHANES 1999-2002, 8- to 14-year-olds by Centers for Disease Control and Prevention Body Mass Index Group

Total N = 1698	Total N (%)	Normal weight⁎	At risk for overweight†	Overweight‡
Total weighted N = 20497949		Total N (%)	Total N (%)	Total N (%)
Age group
Younger (8- to 11-year-olds)	1067(62.8)	666(65.4)	181(17.1)	220(17.5)
Older (12- to 14-year-olds)	631(37.2)	383(67.8)	108(14.7)	140(17.5)
Sex
8- to 11-year-old boys	550(32.4)	348(66.5)	83(16.0)	119(17.6)
12- to 14-year-old boys	296(17.4)	172(62.2)	54(20.0)	70(18.0)
8- to 11-year-old girls	517(30.5)	318(64.2)	98(18.5)	101(17.3)
12- to 14-year-old girls	335(19.7)	211(73.1)	54(9.8)	70(17.1)
Race/ethnic group
8- to 11-year-old non-Hispanic whites	302(17.8)	207(68.0)	52(17.4)	43(14.6)
12- to 14-year-old non-Hispanic whites	167(9.8)	120(72.8)	22(12.6)	25(14.6)
8- to 11-year-old non-Hispanic blacks	390(23.0)	236(60.0)	62(15.7)	92(24.3)
12- to 14-year-old non-Hispanic blacks	194(11.4)	110(57.0)	40(20.9)	44(22.2)
8- to 11-year-old Mexican Americans	375(22.1)	223(59.8)	67(17.7)	85(22.5)
12- to 14-year-old Mexican Americans	270(15.9)	153(56.4)	46(16.8)	71(26.8)

National prevalence estimates and 95% confidence intervals for crude and adjusted values of MSRF by weight group are presented in Table IV. Overall, for all risk factors examined, as weight increased, so did the percentage of those with abnormal risk factors for both the crude and adjusted values. With the exception of HDL cholesterol and fasting glucose, the relationship between increased weight and increased percent of those with abnormal risk factors was clear; as weight increased, so did the percentage of those with metabolic syndrome risk. HDL cholesterol and fasting glucose showed slightly lower rates of abnormal values for those at-risk for overweight compared with those of normal weight.

Table IV. National prevalence estimates and 95% confidence intervals for crude and adjusted values of cardiometabolic risk factors by CDC weight category, NHANES 1999 to 2002

Younger (8 to 11 years old) (N = 1067)⁎			Older (12 to 14 years old) (N = 631)†
	Crude value % (95% CI)	Adjusted value % (95% CI)		Crude value % (95% CI)‡	Adjusted value % (95% CI)∥
Waist circumference			Waist circumference
Normal	0.00	10.39(7.41-14.40)	Normal	0.00	13.75(9.60-19.31)
At risk	0.22(0.03-1.67)	87.61(80.05-92.57)	At risk	8.56(3.11-21.42)	87.37(77.00-93.46)
Overweight	31.29(24.14-39.46)	99.46(97.50-99.88)	Overweight	76.72(64.18-85.85)	99.37(95.33-99.92)
Systolic blood pressure			Systolic blood pressure
Normal	4.97(1.52-9.16)	4.97(1.52-9.16)	Normal	2.26(1.00-5.02)	2.26(1.00-5.02)
At risk	14.81(9.62-22.13)	14.81(9.62-22.13)	At risk	11.36(4.45-26.09)	11.36(4.45-26.09)
Overweight	19.02(11.91-28.97)	19.02(11.91-28.97)	Overweight	20.87(12.37-33.00)	20.87(12.37-33.00)
Diastolic blood pressure			Diastolic blood pressure
Normal	3.23(2.04-5.07)	3.23(2.04-5.07)	Normal	4.93(2.49-9.52)	4.93(2.49-9.52)
At risk	7.59(4.35-12.93)	7.59(4.35-12.93)	At risk	4.56(1.34-14.41)	4.56(1.34-14.41)
Overweight	10.39(6.80-15.57)	10.39(6.80-15.57)	Overweight	7.63(3.15-17.37)	7.63(3.15-17.37)
HDL cholesterol			HDL cholesterol
Normal	11.04(8.04-14.97)	4.74(2.76-7.95)	Normal	11.67(7.29-18.15)§	3.14(1.13-8.39)
At risk	31.81(21.69-44.01)	7.10(4.12-11.99)	At risk	24.24(14.62-37.40)	1.94(1.02-3.65)
Overweight	36.21(28.35-44.88)	13.55(6.25-26.93)	Overweight	44.88(31.36-59.21)	19.09(9.71-34.09)
≥3 Risk factors			Triglyceride
Normal	0.00	1.00(0.15-6.47)	Normal	17.50(11.72-25.30)	5.20(2.56-10.31)
At risk	0.22(0.03-1.67)	3.96(1.23-12.01)	At risk	15.47(7.00-30.81)	6.89(3.41-13.41)
Overweight	6.50(3.82-10.86)	9.51(5.59-15.71)	Overweight	52.40(41.65-62.94)	26.26(16.40-39.26)
Total %	1.17	2.99
Weighted size	128121	326563	Fasting glucose
			Normal	12.30(8.75-17.03)	12.30(8.75-17.03)
2 Risk factors			At risk	9.61(4.52-19.30)	9.61(4.52-19.30)
Normal	2.35(1.10-4.93)	1.06(0.18-6.16)	Overweight	21.83(13.40-33.50)	21.83(13.40-33.50)
At risk	31.83(22.09-43.47)	5.03(1.72-13.82)
Overweight	35.39(24.46-48.09)	18.88(12.64-27.23)	≥3 Risk factors
Total %	13.17	4.85	Normal	0.77(0.15-3.86)	0.70(0.12-4.11)
Weighted size	1438309	530095	At risk	2.98(0.62-13.04)	2.27(1.29-3.95)
			Overweight	43.76(33.27-54.85)	26.28(16.71-38.78)
1 Risk factor			Total %	8.63	5.41
Normal	19.36(15.28-24.22)	16.71(12.70-21.67)	Weighted size	825969	518410
At risk	54.56(44.13-64.60)	42.01(30.96-53.92)	2 Risk factors
Overweight	54.56(43.80-64.91)	36.73(30.17-43.81)	Normal	7.79(4.52-13.09)	10.50(6.69-16.11)
Total %	31.54	24.54	At risk	31.28(20.19-45.03)	15.98(7.63-30.43)
Weighted size	3444779	2680240	Overweight	29.06(19.00-41.70)	22.97(15.77-32.22)
			Total %	14.96	13.49
			Weighted size	1432547	1291809
			1 Risk factor
			Normal	25.18(19.15-32.35)	25.06(18.67-32.77)
			At risk	56.56(42.13-69.95)	32.13(21.56-44.92)
			Overweight	44.03(32.59-56.14)	22.46(14.38-33.31)
			Total %	33.09	25.64
			Weighted size	3168110	2455451

The proportion of 12-to-14 year olds overall, regardless of weight, who had ≥3 or more abnormal risk factors, was 8.63% (weighted N = 825969) using the crude profile and about 5% (weighted N = 518410) using the adjusted profile. Prevalence estimates ranged from 1.17% to 3% for 8- to 11-year-olds, depending on the cutoff threshold. Overall, the crude and adjusted cutoff threshold values often provided substantially different prevalence rates of both individual and ≥3 MSRF.

For both age groups, there were more overweight children compared with at-risk for overweight and normal weight children that had ≥3 MSRF present (Table IV). This was generally true for <3 MSRF for both age groups (Table IV); among the younger age group, using the adjusted profile 35% of those who were overweight had 2 abnormal MSRF compared with 32% of at-risk for overweight and 2% of normal weight, respectively. Using the crude profile, 19% of those overweight in the younger age group had 2 abnormal MSRF, compared with 5% of those at risk for overweight and 1% of those who were normal weight. Among the older age group, the same general trends held true; of those overweight, using the crude profile, 29% had 2 abnormal MSRF, compared with 31% of those at-risk for overweight and 8% of those who were normal weight.

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Discussion 

We report national prevalence estimates of metabolic syndrome risk profiles among 8- to 11-year-olds, using an age-, sex-, and ethnicity-adjusted definition and a clear relationship between an increase in weight and increased metabolic syndrome risk. Furthermore, we found a similar percentage of overweight in both age groups, indicating that problems with overweight start at a young age. The use of crude versus adjusted cutoff thresholds for individual risk factors often revealed large differences in prevalence rates for both age groups. Early onset of obesity with associated risk factors may increase the likelihood of cardiovascular disease and type 2 diabetes, not only in adulthood but potentially in late childhood and early adulthood.

Childhood overweight is currently a major public health problem not only in the United States but worldwide, yet relatively little is known about the health consequences of being overweight as a preadolescent and/or adolescent. Identifying young children with elevated MSRF profiles is becoming a clinical and public health priority because it is possible that effective interventions that target cardiovascular risk can be more successfully instituted in youth rather than to modify behaviors later when deleterious health habits are well established.²⁷

We did not analyze children 15 to 19 years old because this analysis has been reported in various NHANES samples.¹⁴, ¹⁵ Given these published estimates of the prevalence of abnormal MSRF, we thought that an analysis of younger children was warranted. More specifically, Cook et al¹⁴ estimated the prevalence of the metabolic syndrome phenotype among an older group of adolescents ages 12 to 19 years, using the NHANES III (1988 to 1994) data set. They reported the overall prevalence to be 4.2%, based on the ATP adult definition of having 3 or more components (90th percentile for waist circumference, 90th percentile for both systolic and diastolic blood pressure, ≥110 mg/dL for triglycerides and fasting glucose, and ≤40 mg/dL for HDL cholesterol). They also found the syndrome in 28.7% of children classified as overweight by CDC percentile definition (≥95th percentile), in 6.8% of at-risk adolescents (BMI 85th to 95th percentile), and in 0.1% of children with a BMI below the 85th percentile. Using a similar (crude) profile for comparison purposes, we found a clustering of ≥3 MSRF in 8.7% of 12- to-14-year-olds (about twice the 4.2% finding cited above) and in 44% of those who are overweight (again, about twice the 28.7% finding cited above). This relative doubling of the prevalence of obesity and overweight in the past 10-year window has been reported elsewhere,¹, ², ³ yet few have reported associated CVD risk factors, particularly in large numbers of 8- to 11-year-olds. Regrettably, our data showed that the prevalence of overweight in the younger children was quite similar to that of the older age group. It should be acknowledged that our higher MS prevalence rates may be due to classification differences, namely our use of the 75th percentile as a cutoff for waist circumference for the adjusted profile versus previous studies that have used the 90th percentile.¹⁴ Interestingly, the authors²⁰ who generated the standardized waist circumference cutoff values for the US pediatric population that were used here stated “Based on these values, the careful attention to children and adolescents with waist circumference values that fall on the 75th and 90th percentiles, according to their ethnic classification and sex, becomes important in the identification—and prevention—of children at risk for various comorbidities, including cardiovascular disease, hyperinsulinemia, and type II diabetes.” Based on their recommendations, previous authors'¹⁴ use of the 75th percentile as a cutoff for waist circumference, and the probability that these current 75th percentile values are similar to those of the 90th percentile only 20 years ago due to the current obesity epidemic, we hope to help move the field forward by presenting an analysis that is different than previous studies, yet critical to addressing the void of a consensus definition of the metabolic syndrome in children.

One of the unique contributions of this study is that it took advantage of the previous NHANES III to generate appropriately adjusted cutoff values based on age, sex, and race-ethnicity to define MSRF in children and applied this information to the 1999-2002 NHANES data. There is recent controversy²⁸, ²⁹, ³⁰ about the definition, validity, and long-term importance of the metabolic syndrome, particularly among children. As this and other analyses show, the threshold values used to define what many would call the metabolic syndrome among children greatly influence estimates of its prevalence. Similarly, our study shows that crude and adjusted threshold values often provided different estimates of risk for these children, even among 8- to 11-year-olds, an age group that has received little attention in the past. The extent to which these cutoff values will truly predict adverse outcomes in these children can only be determined with longitudinal follow-up. Furthermore, longitudinal studies would be able to determine whether or not the most common MSRF identified in this paper do in fact result on adult-onset disease. Future studies exploring various MSRF among different pediatric populations might also take advantage of these available and adjusted estimates rather than applying one crude cutoff for an entire population.

The primary limitation of this analysis was not having (1) fasting glucose values and (2) appropriate weights available to analyze triglycerides for the 8- to 11-year-old children. Creating the appropriate weights for the triglyceride subsample in those younger than 12 years old would allow for comparisons across age groups. However, our data are likely to underrepresent the true prevalence of metabolic syndrome in this age group, as we were not able to analyze this other important MSRF. Finally, we did not have Tanner values, which would have allowed us to analyze how the onset of puberty affects the presence or onset of metabolic syndrome. This subject warrants further investigation.

Identifying children at the earliest stages of chronic disease onset should be the goal of clinical practice, yet there have been no clear guidelines established in terms of what defines metabolic syndrome risk as well as appropriate MSRF cutoff thresholds among young adolescents. If young adolescents are identified early in the disease process, lifestyle and/or clinical interventions can be instituted when they are potentially more effective. Only continued longitudinal follow-up of well-characterized pediatric cohorts into adulthood will provide sufficient information on appropriate age-, sex-, and race/ethnicity-specific cardiovascular risks in childhood.

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We acknowledge the helpful suggestions of Drs. Samuel Gidding, Stephen Daniels, John Orav, and Matthew Gillman.

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