J-009 ASSOCIATION BETWEEN BLOOD PRESSURE, ADIPOSITY AND LIFESTYLE FACTORS IN ADOLESCENTS

Background Hypertension is becoming an increasingly important problem in adolescents secondary to the ongoing obesity epidemic and increased burden of poor lifestyle habits. We sought to determine the burden of hypertension in this population and characterize the association between blood pressure, adiposity and lifestyle factors. Methods A population-based cross sectional study of 4,104 grade 9 students (14–15 years old, 51% males) was performed as part of the Heart Niagara Healthy Heart Schools’ Program. Measurements included blood pressure, adiposity (body mass index and waist circumference) and lifestyle assessment (nutrition, physical activity and sleep). Blood pressure was converted to age, gender and height specific percentiles and z-scores, and classified as normal (<90th percentile), pre-hypertensive (<95th) and hypertensive (≥95th). Associations between blood pressure, adiposity and lifestyle factors were assessed in linear regression models adjusted for age at enrollment and gender. Results Median blood pressure z-score was −0.6 (IQR: −1.3; −0.1) for systolic and +0.0 (IQR: −0.4; +0.6) for diastolic, with 5.1% of subjects classified as pre-hypertensive and 3.5% as hypertensive. Both increasing waist circumference percentile and body mass index percentile were associated with increasing blood pressure z-score, with a positive interaction between the waist circumference percentile and body mass index percentile (p < 0.001). Lower levels of physical activity (both mild and moderate intensity) (p = 0.04) and higher screen time (p < 0.001) were associated with higher systolic blood pressure z-score. Nutrition and sleep were not associated with blood pressure. Increasing number of days per week with moderate to vigorous physical activity was found to be a mediating factor in the association between adiposity and blood pressure z-score (p = 0.01). Conclusions The association between increased adiposity and increased blood pressure is mediated by physical activity, but not by nutrition or sleep. Improving physical activity levels might be the primary focus of lifestyle interventions aimed at adolescents.