Low Systolic Blood Pressure and Vascular Mortality Among More Than 1 Million Korean Adults

Abstract

BACKGROUND: The association between low systolic blood pressure (SBP) and vascular disease is unclear, especially in nonclinical populations.

METHODS AND RESULTS: We studied 1?235?246 individuals who participated in routine medical examinations between 1992 and 1995. The hazard ratios (HRs) were adjusted for potential confounders. During 22.7 million person-years of follow-up, 34?816 individuals died of atherosclerotic vascular diseases. An increase in SBP was directly related to an increase in vascular mortality at SBP above ?100 mmHg. The group with the lowest SBP (<90 mm?Hg) had a higher HR for mortality from atherosclerotic vascular disease (HR, 1.53; 95% confidence interval, 1.15-2.03) in comparison with those with an SBP of 90 to 99 mm?Hg. The HR associated with the lowest SBP was 2.54 (95% confidence interval, 1.51-4.29) for ischemic heart disease and 1.21 (95% confidence interval, 0.79-1.85) for stroke. Regarding stroke subtype, mortality from hemorrhagic stroke (HR per 10 mm?Hg increase, 0.53; 95% confidence interval, 0.29-0.96), rather than mortality from ischemic stroke (HR per 10 mm?Hg increase, 1.00; 95% confidence interval, 0.51-1.97), was inversely associated with SBP when SBP fell to <100 mm?Hg. Even when excluding the first 5 years of follow-up, the HRs associated with the lowest SBP did not decrease. The inverse association between SBP and vascular mortality in the range <100 mm?Hg tended to be apparent in people aged 60 to 95 years in comparison with individuals aged 30 to 59 years.

CONCLUSIONS: J-curve associations exist between SBP and vascular mortality, which reach a nadir at ?100 mm?Hg. SBP of <90 mm?Hg may portend death from vascular disease, particularly from ischemic heart disease.