Mortality trends in isolated systolic, diastolic, and combined hypertension: insights from NHANES database

Hypertension is a leading risk factor for cardiovascular disease and mortality. It is often treated as a uniform entity despite evidence highlighting distinct outcomes associated with isolated systolic hypertension (ISH), isolated diastolic hypertension (IDH), and combined systolic-diastolic hypertension (SDH). ISH predominates in older adults and is linked to adverse outcomes through arterial stiffness and increased pulse pressure, whereas IDH is more common in younger populations, with unclear long-term mortality implications. In this study we aim to explore differences in mortality between ISH, IDH and SDH in the general population and in patients with coronary artery disease (CAD).

We conducted a longitudinal analysis using National Health and Nutrition Examination Survey data (1999-2020), examining 47,582 adults aged 20 to 84. Participants were categorized by hypertension subtypes: ISH, IDH, SDH, or normotensive. Mortality data (1999-2018) were obtained via the National Death Index. Primary outcomes included demographic and clinical differences across groups; secondary outcomes assessed all-cause mortality using weighted logistic regression and Kaplan-Meier survival analysis. Analyses were stratified by CAD status and adjusted for key sociodemographics and comorbidities.

ISH patients were older (mean age 65.9) with higher Medicare coverage and lower education levels; IDH patients were younger, predominantly male, and more likely to be uninsured. Age-adjusted mortality was highest in ISH (adjusted odds ratio [aOR], 1.32, 95% confidence interval [CI], 1.24-1.41), followed by SDH (aOR, 1.60, 95% CI, 1.39-1.84). IDH showed no significant mortality risk at blood pressure (BP) ≥ 130/80 but demonstrated increased risk at diastolic BP ≥ 90 mmHg (aOR, 1.45, 95% CI, 1.12-1.89). ISH remained a significant mortality predictor after adjusting for age. IDH showed a shift from apparent protection in unadjusted models to risk after adjustment, suggesting heterogeneity based on age and severity.

This study sheds focus on systolic and diastolic components of hypertension. ISH is associated with increased mortality, independent of age, and should prompt prioritizing systolic control. IDH-more prevalent in younger adults-warrants age-specific management strategies. Findings support differential treatment thresholds for hypertension subtypes and underscore the need for longitudinal studies to better define IDH's long-term risk.