FURTHER EVIDENCE FOR BENEFITS OF LOWER BLOOD PRESSURE IN MIDDLE AND OLD AGE
CTSU Press Release.
EMBARGO: 00.01hrs GMT FRIDAY 11 JANUARY 2002
An article in this week's issue of THE LANCET shows that blood pressure is even more strongly related to the risks of death from cardiovascular causes than was previously realised.
In collaboration with investigators around the world, Sarah Lewington and colleagues from the Clinical Trial Service Unit and Epidemiological Studies Unit in Oxford, UK, combined data from 61 previous prospective studies, which involved a total of one million people from Europe, North America, Australia, Israel, China and Japan.
During 12.7 million person-years of follow-up there were 120,000 deaths involving 56 000 vascular deaths (12 000 stroke, 34 000 ischaemic heart disease [IHD], 10 000 other vascular) and 66 000 other deaths. The investigators report that lower blood pressure is strongly related to lower risk of death from cardiovascular causes throughout the so-called "normal range" (i.e. down to 115 mm Hg systolic and 75 mm Hg diastolic); for example, at ages 40-69 years, each blood pressure difference of 20 mm Hg systolic or 10 mmHg diastolic is associated with more than a twofold difference in the stroke death rate, and with twofold differences in the death rates from ischaemic heart disease and from other vascular causes. Moreover, the study shows that blood pressure is an important cause of vascular mortality not only in middle age but also among people in their seventies or eighties.
Sarah Lewington comments: "Not only do the present analyses confirm that there is a continuous relationship with risk throughout the normal range of usual blood pressure (down at least as far as 115/75 mm Hg), but they also demonstrate that within this range the usual blood pressure is even more strongly related to vascular mortality than had previously been supposed. Randomised trials (which typically last only a few years) have shown that blood-pressure lowering can produce rapid reductions in vascular disease risk, and this meta-analysis provides complementary evidence of the even greater differences in risk that are likely to be produced by really prolonged differences in blood pressure. For example, a 10 mm Hg lower usual SBP or 5 mm Hg lower usual DBP would, in the long term, be associated with about 40% lower risk of stroke death and about 30% lower risk of death from ischaemic heart disease or other vascular causes throughout middle age. For the general population, producing persistent reductions in average blood pressure of just a few mm Hg by some widely practicable methods (such as, perhaps, reducing sodium intake in manufactured foods) should avoid large absolute numbers of premature deaths and disabling strokes, especially in places that, perhaps for other reasons, have relatively high stroke rates (such as Northern China) or high IHD rates (such as Eastern Europe)."
Contact: Dr Sarah Lewington, Clinical Trial Service Unit & Epidemiological Studies Unit, CTSU Harkness Building, Radcliffe Infirmary, OXFORD OX2 6HE, UK; T) +44 (0)1865 557241; F) +44 (0)1865 558817; E) sarah.lewington@ctsu.ox.ac.uk
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