Secular trends in BMI and blood pressure among children and adolescents: the Bogalusa Heart Study.

Abstract

The prevalence of obesity among children and adolescents increased by almost threefold from the 1970s to 2000. We examined whether these secular changes in BMI were accompanied by increases in blood pressure levels. A total of 24,092 examinations were conducted among 11,478 children and adolescents (aged 5-17 years) from 1974 to 1993 in the Bogalusa Heart Study (Louisiana). The prevalence of obesity increased from 6% to 17% during this period. In contrast, only small changes were observed in levels of systolic blood pressure (SBP) and diastolic blood pressure (DBP), and neither mean nor high (based on the 90th percentile from the Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents) levels increased over the 20-year period. Within each race-gender group, mean levels of SBP did not change, whereas mean levels of DBP decreased by 2 mm Hg (P < .001 for trend). Levels of BMI were positively associated with levels of SBP and DBP within each of the 7 examinations, and controlling for BMI (along with other covariates) indicated that only ~60% as many children as expected had high levels of blood pressure in 1993. Our finding that levels of DBP and SBP among children in this large sample did not increase despite the increases that were seen in obesity indicates that changes in blood pressure levels in a population do not necessarily parallel changes in obesity. Additional study of the potential characteristics that have ameliorated the expected increase in high blood pressure could lead to further reductions in risk.