Project Summary The overall reduction in the rate of cardiovascular disease (CVD) over the past decades in the US has not extended to young adults aged 18-39 years. An increasing prevalence of CVD risk factors in young adults, including high blood pressure (BP), likely contributed to the increase in CVD rates. About 20% of US young adults have stage 1 or 2 hypertension (BP 130-139/80-89 mm Hg and ≥140/90 mm Hg, respectively). Despite the high prevalence of hypertension in young adults and its association with CVD, there is little evidence to guide BP screening and treatment recommendations in young adults. For BP screening, >25% of young adults in the US with hypertension are unaware that they have it. Moreover, social determinants of health (SDOH), an important influence on the health of young adults, is not considered in BP screening recommendations. For BP management, the benefits of initiating antihypertensive medications during young adulthood are unknown and are extrapolated from data among older adults. Due to the lack of evidence, most of the 13 million young adults with stage 1 hypertension are currently not recommended to initiate antihypertensive medication, and 50% (2.5 million) of young adults with stage 2 hypertension are currently left untreated. Although randomized controlled trials (RCTs) with hard CVD outcomes will provide definitive evidence, it may not be feasible to perform such a trial in young adults due to high costs and long follow-up time needed to determine CVD risk reduction benefits. In the absence of RCTs, high quality observational and simulation studies can provide clinically relevant and actionable evidence for policy makers, patients, and clinicians in a cost-efficient manner. The overall study objectives are to determine the optimal BP screening intervals for young adults and to identify those with a high risk of premature and/or lifetime CVD who may benefit from antihypertensive medication during young adulthood. The aims of this study are to (1) determine BP screening intervals by examining the timing of transitioning from normal BP into stage 1 or 2 hypertension and long-term BP trajectories, (2) identify characteristics of young adults with stage 1 or 2 hypertension who are at high risk for adverse CVD or renal outcomes, (3) quantify the benefits and harms of antihypertensive medication among young adults with stage 1 or 2 hypertension by emulating a hypothetical RCT using a large observational database and state-of-the-art statistical models to minimize confounding and selection bias, and (4) compare the short- and long-term health and economic impact of BP screening and management strategies for US young adults identified in Aims 1 to 3 vs. current BP guidelines. To address these aims, we will study ~500,000 young adults aged 18-39 years from both Kaiser Permanente Southern California and four epidemiologic cohorts. Findings from this study will inform future BP guidelines, reduce health inequity by direct...