Waist circumference and body mass index in Chinese children: cutoff values for predicting cardiovascular risk factors.
BACKGROUND
Body mass index (BMI) and waist circumference (WC) correlate with cardiovascular (CV) risk factors in childhood which track into adulthood. WC provides a measure of central obesity, which has been specifically associated with CV risk factors. Reference standards for WC, and for WC and BMI risk threshold values are not established in Chinese children.


OBJECTIVE
To construct reference percentile charts of WC, establish relationships between WC, BMI and other risk factors, and propose WC and BMI threshold values predictive of CV risk factors in Hong Kong ethnic Chinese children.


METHODS
Weight, height, waist and hip circumference were measured in 2593 (52% boys, 47% girls) randomly sampled Hong Kong school children aged 6-12 years. In 958 of these and 97 additional overweight children (n=1055), the relationships between WC, BMI, waist/hip and waist/height ratio and six age-adjusted CV risk factors (>85% percentile levels of blood pressure (BP), fasting triglycerides, low-density lipoprotein (LDL) cholesterol, glucose and insulin levels, and <15% percentile levels of high-density lipoprotein (HDL) cholesterol) were studied. Receiver-operating characteristic analysis was employed to derive optimal age-adjusted sex-specific WC and BMI thresholds for predicting these measures of risk.


RESULTS
WC percentiles were constructed. WC correlated slightly more than BMI with CV risk factors and most strongly with insulin and systolic BP, but poorly or not with LDL and glucose. Optimal WC and BMI risk thresholds for predicting four of these six CV risk factors were ca. the 85th percentiles (sensitivities approximately 0.8, specificities approximately 0.87) with age-specific cutoff values in girls/boys from approximately 57/58 to approximately 71/76 cm and 17/18 to 22/23 kg/m(2).


CONCLUSIONS
These are the first set of WC reference data for Chinese children. WC risk cutoff values are proposed which, despite a smaller waist in Chinese children, are similar to those reported for American children. WC percentiles may reflect population risk.
Sung
R Y T
RY
Department of Paediatrics, The Chinese University of Hong Kong, Hong Kong, China. yntzsung@chuk.edu.hk
Yu
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Choi
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McManus
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Xu
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Chan
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Chan
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D000293:Adolescent; D017677:Age Distribution; D019540:Area Under Curve; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D002648:Child; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D007328:Insulin / Q000097:blood; D008074:Lipoproteins / Q000097:blood; D008297:Male; D009765:Obesity / Q000150:complications / Q000453:epidemiology / Q000503:physiopathology; D011159:Population Surveillance / Q000379:methods; D012307:Risk Factors; D017678:Sex Distribution; D014280:Triglycerides / Q000097:blood; D049629:Waist-Hip Ratio
D001786:Blood Glucose; D007328:Insulin; D008074:Lipoproteins; D014280:Triglycerides