The population-based prevalence of hypertension and correlates of blood pressure among Australian children

Objective: Hypertension is increasingly recognized as a disease spanning the entire life course. Continued efforts to refine the diagnosis and management of hypertension in children are highlighted by the recent American Academy of Pediatrics (AAP) guidelines, which include lower threshold values than the previous reference standard (Fourth Report). We aimed to determine the population-based prevalence of children exceeding thresholds for hypertension using these two guidelines. We also sought to identify the correlates of blood pressure (BP) among Australian children. Methods: Cross-sectional data from the Growing Up in Australia: Longitudinal Survey of Australian Children were analyzed. Blood pressure was measured in 7139 Australian children aged 10–12 years and sampled using population-based methodology. The association between BP and explanatory variables linked to BP in other populations was examined using multiple linear regression with fractional polynomial terms for continuous, non-linear relationships. Results: The threshold for hypertension was exceeded in 3.1% and 5.4%, and prehypertension in 3.0% and 3.7% of children, using the Fourth Report and AAP guidelines respectively. Children at the threshold for obesity had a 9.1 mmHg higher adjusted BP than those on the 50th centile for body mass index (BMI) (95% CI 8.4 to 9.9). BMI had a non-linear relationship with BP, and the magnitude of association between BMI and BP increased with BMI. Socioeconomic status, hypertension during pregnancy, birth weight, and sports participation were also independently associated with BP. Conclusions: Using the AAP guidelines is likely to substantially increase the population prevalence of hypertension. The association between BMI and BP was strongest and non-linear for obese children, who should be the focus of interventional trials.