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.
Keywords: blood pressure; cohort studies; hypotension; mortality; vascular diseases.
© 2016 American Heart Association, Inc.