To investigate age-related shifts in the relative importance of SBP and DBP as predictors of cardiovascular mortality and all-cause mortality and whether these relations are influenced by other cardiovascular risk factors.
Using 42 cohorts from the MORGAM Project with baseline between 1982 and 1997, 85 772 apparently healthy Europeans and Australians aged 19–78 years were included. During 13.3 years of follow-up, 9.2% died (of whom 7.2% died due to stroke and 21.1% due to coronary heart disease, CHD).
Mortality risk was analyzed using hazard ratios per 10-mmHg/5-mmHg increase in SBP/DBP by multivariate-adjusted Cox regressions, including SBP and DBP simultaneously. Because of nonlinearity, SBP and DBP were analyzed separately for blood pressure (BP) values above and below a cut-point wherein mortality risk was the lowest. For the total population, significantly positive associations were found between stroke mortality and SBP [hazard ratio = 1.19 (1.13–1.25)] and DBP at least 78 mmHg [hazard ratio = 1.08 (1.02–1.14)], CHD mortality and SBP at least 116 mmHg [1.20 (1.16–1.24)], and all-cause mortality and SBP at least 120 mmHg [1.09 (1.08–1.11)] and DBP at least 82 mmHg [1.03 (1.02–1.05)]. BP values below the cut-points were inversely related to mortality risk. Taking into account the age × BP interaction, there was a gradual shift from DBP (19–26 years) to both DBP and SBP (27–62 years) and to SBP (63–78 years) as risk factors for stroke mortality and all-cause mortality, but not CHD mortality. The age at which the importance of SBP exceeded DBP was for stroke mortality influenced by sex, cholesterol, and country risk.
Age-related shifts to the superiority of SBP exist for stroke mortality and all-cause mortality, and for stroke mortality was this shift influenced by other cardiovascular risk factors.