Jian Liu, PhD

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Cardiovascular Risk Factors and Anthropometric
Measurements of Adolescent Body Composition A
Cross-sectional Analysis of the NHANES III

• Jian Liu, PhD
• Brock University
• Canada

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Introduction

• Cardiovascular disease (CVD) is the major killer
  among the adult population in the industrialized
  nations.
• CVD is also one of the leading causes of
  morbidity and mortality in many developing
  countries.

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Deaths by Causes in the World
-WHO Health Report, 2004
Communicable diseases, maternal perinatal
conditions, and nutritional deficiencies
Injury
All malignant neoplasms
Non-communicable diseases
Coronary heart disease
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• CVD is the result of an interaction between
  genetics and environmental risk factors with a
  long induction time period.

• Among adults, obesity and type 2 diabetes are
  well documented as having an association with the
  morbidity and mortality of CVD.

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Epidemic of overweight and obesity world wide

• 1.1 billion adults overweight (BMIgt25 kg/m2)
• 312 million obese (BMIgt 30 kg/m2)
• 155 million children overweight or obese from
  International Obesity Task Force
• If modifying the definition of overweight for
  Asians as BMIgt23 kg/m2, 1.7 billion adults
  worldwide can be classified as overweight.

Haslam DW, et al. Lancet 2005 366 1197-209
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Diabetes a growing challenge globally in the
future
Hossain, P. et al. N Engl J Med 2007 356(3)
213-5
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• People with obesity and diabetes are often
  insulin resistance.
• It is noted that among adults short stature
  (height or length of leg) is associated with the
  risk of CVD. It was hypothesized that those
  observed CVD risk associations in adulthood might
  have been programmed at foetal stage.
• Environmental factors in utero or early life may
  have a profound influence on the initiation of
  insulin resistance.

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Health Professionals Follow-up Study
G. C. Curhan et al., Circulation 1996 (94) 3246
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Anthropometric Measurements and CV Risk Factors

• A reverse relationship between height (or leg
  length) and coronary heart disease has been
  observed in a number of prospective studies.

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Goal of the study

• To assess the association between certain
  cardiovascular risk factors which are commonly
  clustered among individuals with insulin
  resistance syndrome (IRS) and adolescents body
  composition measurements.

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Methods

• The NHANES III Survey and Participants
• Conducted between 1988 and 1994.
• approximately 40,000 participants aged 2 month
  and older.
• The standardized interview and examination
  procedures used throughout NHANES III were based
  on a two-stage process to collect data both in a
  home interview and during a medical examination.
• All participants who completed the home interview
  were invited to participate in the detailed
  medical examination conducted at a mobile
  examination center (MEC).

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• A total of 2,216 adolescents aged 12 - 16 years
  old participated in the NHANES III.
• 1,068 adolescents who had fasted gt 8 hrs and
  had no missing information on glucose,
  triglycerides (TG), high-density-lipoprotein
  (HDL) cholesterol and systolic blood pressure
  (SBP) were included in this study.

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Anthropometric measurements

• Body weight (kg)
• Standing height (cm)
• Sitting height (cm)
• Leg length (standing height - sitting height,
  cm)
• Waist circumference (cm)
• Middle-up arm circumference (cm)
• Buttocks circumference (cm)
• Thigh circumference (cm)

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BMI z-score

• BMI was standardized for age and sex by
  conversion to a BMI z- score and the 85th
  percentile is used to identify a group of
  children at increased risk of obesity Box GE CDR.
  J Roy Stat Soc, Series B 26, 211-252. 1964.

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Blood measurements

• Total cholesterol (total-c, mg/dl)
• Triglycerides (TG, mg/dl)
• High-density-lipoprotein cholesterol (HDL-c,
  mg/dl)
• Low-density-lipoprotein cholesterol (LDL-c,
  mg/dl) total HDL cholesterol TG/5
• Non-high-density-lipoprotein (non-HDL-c, mg/dl)
  total HDL cholesterol
• Glucose (mg/dl)

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Blood pressure

• Was measured approximately 6 times (3 times at
  the household interview and 3 times during the
  MEC examination) . The six or fewer of K1
  measurements were used to calculate the average
  of systolic BP.

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Confounding variable measurements

• Age at interview (yrs)
• Race (1 white, 0 non-white)
• Physical activity times per week play or
  exercise enough to make sweat and breathe hard,
  and
• TV watching hrs in the previous day.

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The Criterion of Insulin Resistance Syndrome (IRS)

• There was no direct measurement of insulin
  resistance in this study. However, we used a
  cluster of metabolic abnormalities that is
  associated with insulin resistance to define
  insulin resistance syndrome.
• The insulin resistance syndrome in children is
  evolving there is no general agreement about the
  overall assessment of this syndrome.
• we used the sex-specific third tertiles of
  glucose, TG, SBP, and first tertile of HDL
  cholesterol to classify the presence of each IRS
  component

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Statistical Analysis

• The Stata/SE 8.2 for Windows (Stata, College
  Station, TX) was used to accommodate proper
  weighting and account for the complex design of
  the NHANES III sample.
• Comparisons between genders
• Trends analyses
• Logistic regression analysis

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RESULTS
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Difference significant (plt.05) by sex in Table 2.
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Length measurements distribution by insulin
resistance status
Females
Males
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Weight, BMI, and girth measurements distribution
by insulin resistance status (Females)
P for trends lt.05
P for trends lt.05
P for trends lt.05
P for trends lt.05
P for trends lt.05
P for trends lt.05
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Weight, BMI, and girth measurements distribution
by insulin resistance status (Males)
P for trends lt.05
P for trends lt.05
P for trends lt.05
P for trends lt.05
P for trends lt.05
P for trends lt.05
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Lipids (mg/dl) distribution by insulin resistance
status
P for trends lt.05
Females
P for trends lt.05
Males
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Glucose and SBP distribution by insulin
resistance status
P for trends lt.05
P for trends lt.05
Females
P for trends lt.05
P for trends lt.05
Males
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Discussion

• The clustered CVD risk factors among adolescents
  are more likely to be associated with body weight
  and measurements related to body girths, but less
  likely to be associated with the measurements
  related to body lengths.
• Those with more insulin resistance syndrome
  components are more likely to carry excess body
  fat, which is distributed over the entire body
  including the abdominal area.

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• The highest mean levels of LDL cholesterol
  observed among adolescents with three or four IRS
  components, in particular among girls, indicates
  that those adolescents are likely to have a high
  risk for CVD in the future .
• The association between ? non-HDL cholesterol and
  ? of IRS components suggests that those
  adolescents with more IRS components have already
  developed a certain degree of abnormal lipid
  profile which may have serious implications in
  their adulthood.

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Limitations strengths

• Limitations
• Not every participant provided a morning blood
  sample.
• Self reported physical activity and time-spent on
  TV watching.
• Strengths
• Measurements are reliable and accurate.
• The NHANES III data.

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In summary

• Our study indicates that the clustered CVD risk
  factors are strongly associated with obesity and
  higher levels of non-HDL cholesterol among
  adolescents.
• These findings suggest directions for
  cardiovascular disease prevention efforts among
  adolescents.
• e.g., examine if foetal nutrition status is
  linked to the CVD risk profile among children and
  adolescnets.

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Acknowledgement

• Dr. Terry Wade, Brock University, Canada
• Dr. Hongzhuan Tan, School of Public Health,
  Central South University, PRC
• Dr. Christopher Sempos, NIH, USA

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Thank you
Email jian.liu_at_brocku.ca
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