Association Between Abdominal Waist Circumference and Blood Pressure In Brazilian Adolescents With Normal Body Mass Index

Obesity is the most common chronic disease in adolescents. In adults, waist circumference (WC) is associated with the presence of cardiovascular risk factors and is also a better predictor of cardiovascular (CV) risk than body mass index (BMI). The association between WC and CV risk factors in adolescents has been poorly explored so far, mainly in those within the normal BMI range. Objective: To evaluate the association between WC and elevated blood pressure (BP) in adolescents with a normal BMI. Methods: Cross-sectional analysis of 73,399 scholars between 12 and 17 years old from the ERICA study, a school-based, national representative study with Brazilian adolescents. Only those within the normal range of BMI were included. The WC was categorized into quartiles for sex and age (Q1 to Q4). For the analysis, BP values >= 90th percentile were considered to indicate elevated BP, what includes hypertension and pre-hypertension. The Poisson Regression model was used and the prevalence ratio was estimated. Results: A total of 53,308 adolescents with normal BMI were included. Prevalence of elevated BP in the overall group was 18.0%. In female adolescents with WC in the lowest quartile for their age, the prevalence of elevated BP was 7.3% (12-14 years) and 6.9% (15-17 years), increasing in the upper quartile to 15.2% and 19.5% respectively, with a prevalence ratio (PR) indicating chance at least two times higher for elevated BP in Q4 (p < 0.001). Similarly, this was observed in boys, with a prevalence of elevated BP of 10.0% and 18.9% in Q1, increasing to 21.4% and 49.6% in Q4 (p < 0.001). Conclusion: In adolescents, there is a strong association of increased WC with BP elevation, even when the BMI is adequate.