Hypertension Across the Life Course: Introduction to an American Journal of Hypertension Compendium

Hypertension contributes to more cardiovascular disease (CVD) events and disability adjusted life years than any other modifiable risk factor in the United States and worldwide.1 Over 100 million US adults and over 1 billion adults worldwide have hypertension.2,3 The prevalence of hypertension increases with age and the lifetime risk for hypertension exceeds 80% among US adults.4 Decades of research have generated evidence that both genetics and environmental exposures contribute to blood pressure (BP).5 Some children and adolescents develop hypertension, which is a risk factor for early onset CVD and a shorter life expectancy.6 Although the vast majority of hypertension does not occur during childhood and adolescence, early life BP levels have a strong association with hypertension risk later in life.7 These issues emphasize the importance of considering the prevention, detection, and treatment of hypertension across the life course. With this background, the editors of the American Journal of Hypertension are proud to present a compendium in the current issue that reviews issues related to hypertension from genetics and childhood through older adulthood. It has been estimated that 20%–50% of hypertension is heritable with the remaining variance explained by environmental exposures.5 Only a small portion of the variability in BP is explained by identified loci.8 In the compendium, Irvin and colleagues provide an overview of data on epigenetic determinants of BP and BP-related target organ damage. They review data from large-scale candidate gene association studies and epigenome wide studies. Data from these studies are providing insights on the role of epigenetic modification, including DNA methylation, histone modification, and RNA-mediated processes on BP. In closing, the authors discuss the need for future studies to address differentially methylated regions, integrating epigenetic layers, intraindividual methylation changes across the life course and functional follow-up. Higher BP levels in childhood and adolescence are associated with the development of hypertension in adulthood.7 Additionally, hypertension in childhood and adolescence is associated with CVD in adulthood.6 These data emphasize the importance of preventing elevated BP and hypertension in children and adolescents. The article in this compendium by Hardy and Urbina review key issues on BP in childhood and adolescence including the definitions, prevalence, and risk factors for hypertension and appropriate approaches to measure BP.9 They review recently published data from the Study of High BP in Pediatrics: Adult Hypertension Onset in Youth (SHIP-AHOY) cohort that showed a linear association between higher daytime systolic BP on ambulatory BP monitoring with increased left ventricular mass index.10 Additionally, they review the evidence for both nonpharmacologic and pharmacologic interventions to lower BP in childhood and adolescence. In closing, this article discusses key evidence gaps including those related to BP measurement and treatment decision making. The incidence of hypertension is high among young adults with 1 study estimating over 20% of young adults develop hypertension before 40 years of age.11 For the compendium, Yano provides a review of the implications of BP levels in young adulthood on CVD risk and other adverse BP-related outcomes.12 This article reviews the implications of the lower BP thresholds in the 2017 American College of Cardiology/American Heart Association BP guideline on the prevalence of hypertension in young adults, the prevalence of hypertension when BP is assessed outside of the office setting using ambulatory BP monitoring, the association of BP with CVD risk, and the association of age of hypertension onset and CVD risk. Additionally, data on different BP phenotypes including isolated systolic hypertension, isolated diastolic hypertension, BP variability, and cumulative BP exposure in young adulthood and CVD risk are reviewed. In closing, the challenges of conducting randomized trials on the benefits and harms of pharmacologic treatment for elevated BP and hypertension are reviewed and potential approaches to undertaking these studies are provided. Many epidemiology studies have focused on the association of BP, assessed at a single time point, with future outcomes. However, BP changes over time and time-averaged BP has added prognostic value to estimates obtained at a single time point.13 While data show that mean SBP increases as a population ages in middle- and high-income regions, INTERSALT study researchers have reported that mean BP does not increase in some populations. Additionally, there is heterogeneity in the changes in BP that individuals within a population experience as they age. This has been well-characterized by life course studies that have conceptualized BP trajectories. For example, BP may start low and stay low (i.e., a low-stable trajectory), start at a moderate level and increase (i.e., a moderate-increasing trajectory), start high and remain elevated (i.e., an elevated stable), or start high and increase (i.e., an elevated increasing trajectory).13 In the compendium, Allen and Khan review data on BP trajectories.14 First, they review the methodologic considerations involved in conceptualizing BP trajectories with the consideration of individual and population trajectories. BP trajectories at different age including in adolescence, pregnancy, and older adulthood are reviewed. An overview of risk factors for different BP trajectories and outcomes associated with these phenotypes is presented. In closing, the need for studies to identify how BP trajectories can be incorporated into clinical care is reviewed. The majority of older adults have hypertension and the incidence of CVD is very high in this population.3,15 However, older adults represent a heterogeneous population with respect to their functional status, the presence of comorbidities, personal experiences, and the environment in which they live. Each of these factors presents challenges with the management of hypertension and achieving BP control consistent with evidence-based guidelines. Within this context, Bowling et al. provide a review of hypertension in older adults for the compendium.16 The prioritization of remaining independent later in life and the role BP control and hypertension management in achieving this goal is discussed. The authors propose a novel framework to consider hypertension management in older adults focused on measurement, planning, treating, and monitoring BP with each step conducted using a patient-centered approach considering function, health conditions, and personal and environmental factors. In closing, the authors review implementation opportunities in routine care to improve BP control among older adults. Hypertension has a major impact on society, costing billions of dollars and leading to millions of CVD events annually as well as substantial disability and a large number of deaths.1 However, it is feasible for people to maintain normal BP as they age and this has the potential to substantially reduce the burden of CVD.17 Among adults with hypertension, the risk for adverse outcomes can be reduced through achievement of guideline-recommended BP levels.18 Preventing hypertension and hypertension-related adverse outcomes including CVD will require interventions across the life course from childhood and adolescence through older age. In providing the 5 articles on hypertension across the life course in the current issue of the American Journal of Hypertension, it is hoped that additional approaches to prevent hypertension and achieve BP control among individuals with hypertension will be developed and widely implemented, ultimately leading to longer healthy lives among all people.