Systolic Blood Pressure, Diastolic Blood Pressure, and Pulse Pressure: An Evaluation of Their Joint Effect on Mortality

Background: The relative importance of blood pressure components (systolic blood pressure, diastolic blood pressure, and pulse pressure) on cardiovascular risk is currently being debated. Many studies, however, are limited by inadequate statistical methods to separate these effects. Objective: To evaluate the joint effect of blood pressure components on all-cause and cardiovascular mortality by using non-parametric and change point models. Design: Prospective cohort study. Setting: 15-year mortality follow-up of participants in the Second National Health and Nutrition Examination Survey. Participants: 7830 white and African-American men and women 30 to 74 years of age, apparently free of cardiovascular disease at baseline. Measurements: Baseline blood pressure, corrected for measurement error. Results: Of the 1588 patients who died, 582 died of cardiovascular disease. Systolic blood pressure was linearly related to all-cause and cardiovascular mortality in younger and elderly participants. The association of diastolic blood pressure with all-cause and cardiovascular mortality was hockey stick-shaped (flat then increasing) in younger participants and J-shaped in elderly participants. Increased pulse pressure was associated with increased risk, decreased risk, or no change in risk depending on age and systolic and diastolic blood pressure. Conclusions: On the basis of these and previous data, the evidence for a monotonic association of systolic blood pressure with all-cause and cardiovascular mortality is compelling, but a J-shaped association for diastolic blood pressure may develop at older age. The complexity of the association of pulse pressure with mortality discourages its use for prognostic or therapeutic decisions.