Abstract
Background: Blood pressure tracks from childhood to adulthood (1). The aims of this study were to identify: groups of individuals sharing systolic blood pressure trajectories from 7 to 38 years; predictors of trajectory group membership; and modifiers of trajectories.Methods: Group-based trajectory modelling (2) was used to identify latent trajectories of blood pressure among participants in the Dunedin Multidisciplinary Health and Development Study (n = 1037), using data collected at ages 7, 11, 18, 26, 32 and 38 years. Predictors (e.g. gender) and modifiers (e.g. body mass index (BMI)) of trajectories were evaluated. Results: Four trajectory groups were identified; 'normal' (21.7 %), 'normal-high' (43.0%); 'prehypertensive' (31.4%) and 'hypertensive' (3.9%). These group trajectories diverged by age 11 and did not intersect over time. Individuals had higher odds of being in the 'prehypertensive' or 'hypertensive' groups compared to the 'normal' group if they were male, had a family history of high blood pressure and a mother with pregnancy hypertension. For example, males had 43.7 higher odds (95% CI 19.5, 97.8) of being in the prehypertensive compared to the normal group. Increasing BMI was associated with statistically significant increases in blood pressure for all trajectory groups, with the coefficient estimate being highest in the hypertensive group. Conclusions: We were able to identify in childhood, groups of individuals at risk of developing high blood pressure using known risk factors. BMI was a significant modifier of blood pressure in the entire population, but reducing BMI may be particularly important for individuals on a trajectory towards developing hypertension.