Tracking of elevated systolic blood pressure among lean and overweight adolescents

Abstract

To determine whether elevated blood pressure tracks to a greater degree in overweight than in lean children. Prospective cohort study. We examined 758 adolescents (mean age 13.4 years) who participated in a longitudinal study of blood pressure. The degree of tracking was examined by cross-classification of sex-specific tertiles of systolic blood pressure (SBP) and body mass index determined at baseline and 5 years later. Those children that were in the highest tertile of SBP and body mass index were considered to be 'overweight with elevated blood pressure'. Those that were in the highest tertile of SBP but lowest tertile of body mean index were considered to be 'lean with elevated blood pressure'. Of those boys that were initially classified as lean with elevated blood pressure, 38% remained so classified compared with 54.6% of those that were initially classified as overweight with elevated blood pressure. Among the girls the respective proportions were 48 and 44.2%. The subjects of each sex who were lean with elevated blood pressure were significantly shorter at baseline than their overweight counterparts, and over the follow-up period experienced a greater mean increase in SBP than their overweight peers. This difference was almost totally explained for the boys once the difference in height change was taken into account. For the girls a difference of 5.9 mmHg remained after covariate adjustment for the change in height. These results fail to support the hypothesis that blood pressure tracks differently in obese and in lean adolescents, particularly once differences in sexual maturation are considered.