Comparison of United Kingdom (UK) and United States (U.S.) hypertension treatment status, physical activity and prospective mortality risk

Background: The 2017 American College of Cardiology/American Heart Association (ACC/AHA) guideline lowered diagnostic threshold for hypertension, encouraging earlier treatment initiation in the U.S. compared to UK, where the National Institute for Health and Care Excellence (NICE) guideline recommends higher thresholds. No comparative study evaluating how different hypertension guidelines and physical activity are jointly associated with mortality outcomes in two countries. Aims: This study compared hypertension prevalence, treatment uptake, blood pressure (BP) levels, and mortality between the UK Biobank (UKBB) and the U.S. National Health and Nutrition Examination Survey (NHANES). We evaluated whether moderate-to-vigorous physical activity (MVPA) modifies mortality risk among different hypertension subgroups (normotensive, medicated hypertension, and unmedicated hypertension). Methods: We harmonized demographic, biomarker, lifestyle, and accelerometer data from UKBB (n=63,452) and NHANES (n=7,397). Comprehensive weighting methods were applied in both cohorts. Accelerometry data was classified using a validated two-stage machine learning Random Forest algorithm. Associations between MVPA and all-cause mortality were examined with restricted cubic spline regression and visualized using Kaplan-Meier survival curves. Results: NHANES showed a higher proportion of treated hypertension (29.9%) and lower average blood pressure (SBP/DBP: 122.2/70.7 mmHg) compared to UKBB (11.7% treated; SBP/DBP: 136.0/81.3 mmHg). Despite lower BP levels, cardiovascular mortality was higher in UKBB (10.3 per 10,000 person-years) compared to NHANES (4.0 per 10,000 person-years). In both cohorts, greater MVPA was linked to lower mortality risk, with the strongest association observed among medicated hypertensives. Notably, NHANES participants with treated hypertension and low MVPA (<10.7 minutes/day) experienced a steeper survival decline, falling to 74% by year 8, compared to 91% in normotensives and 79% in untreated hypertensives. Conclusion: Despite higher treatment prevalence and lower average BP levels in NHANES, mortality remained higher compared with UKBB, suggesting that differences in mortality patterns may relate to broader cardiometabolic profiles and PA patterns beyond pharmacological management alone. Across both cohorts, higher levels of MVPA were associated with lower all-cause mortality, with the strongest associations were observed among individuals with medicated hypertension.