Contribution of body fat and fat pattern to blood pressure level in school children.

OBJECTIVE

The study aims are investigating the effect of body fat and fat localization on blood pressure.

DESIGN

Case-control study.

SETTING

The study was carried out in the school health primary care.

SUBJECTS

The case-control study included 220 obese and 220 non-obese children aged 7-18 years from Al Ain city, United Arab Emirates between September 1992 to May 1993 inclusive. Each group consisted of 120 males and 100 females. Two schools were randomly selected from each of the three educational stages: primary, junior and secondary. The inclusion criterion for cases comprised children with body mass index (BMI; Quetelet index), > 90th percentile of age and sex-specific reference data of the French population. Non-obese healthy controls were randomly selected from the same classes from where obese children were identified in order to ascertain that cases and controls were matched by age and sex.

MEASUREMENTS

Anthropometric measures (weight, height, waist and hip circumferences), systolic and diastolic blood pressure were measured. To minimize inter-observer error, blood pressure was measured by one physician. We also collected information about other confounding social variables (family history of obesity and mother's education) and behavioural variables (preferred diet and physical activity).

RESULTS

There was significant difference of systolic and diastolic blood pressure means between obese and non-obese children (P < 0.001) in both males and females. Applying the multiple linear regression analysis to fix the confounding effect of age, sex, social and behavioural factors, the fatness index, BMI, was significantly related to systolic (P < 0.0004) and diastolic (P < 0.0001); while waist-to-hip circumference ratio (WHR) was not significant (P = 0.803 in systolic and P = 0.648 in diastolic blood pressure respectively).

CONCLUSIONS

Systolic and diastolic blood pressure showed a positive relationship with the fatness index BMI, but not with WHR, in both boys and girls. This is an evidence that WHR may not be a reliable indicator of body fat distribution in children.