Predictors of blood pressure in a cohort of school-aged children.

OBJECTIVES

To examine anthropometric measures and birthweight as predictors of blood pressure (BP) in a cohort of children.

DESIGN

Cross-sectional and longitudinal study comprising baseline anthropometric and BP measurements conducted in 1994 (n=1230), with follow-up in 1997 (n=628).

SETTING

Seventy-five inner-Sydney primary schools.

PARTICIPANTS

School children aged 8-9 years at baseline and 11-12 years at follow-up.

MAIN OUTCOME MEASURES

Systolic and diastolic BP (SBP and DBP).

STUDY FACTORS

Current weight, body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHR), weight gain since birth and birth weight. Potential confounders: age, sex and socioeconomic status (on the basis of the area of residence).

RESULTS

Current weight was significantly associated with both SBP and DBP in boys and girls at baseline and follow-up. BMI and WC were similar predictors of SBP and DBP in each survey, but longitudinal BMI change has a stronger association with SBP (r=0.43, P<0.001) and DBP (r=0.26, P<0.001) than changes in WC (r=0.18, P<0.001 for SBP and r=0.16, P<0.001 for DBP) and WHR in boys with the similar results for girls. The unadjusted associations between SBP and DBP and birthweight were nonsignificant. After adjustments for age, height and socioeconomic status, however, the association becomes negative and significant in boys (beta=-1.47, P=0.04 for SBP and beta=-1.33, P=0.03 for DBP).

CONCLUSION

Longitudinal change in BMI is a better predictor of BP than change in WC or the WHR, although cross-sectional measurements of BMI and WC are very similar predictors of BP. In preventing subsequent adverse effects on BP, attending to body weight during childhood is important.