michael s
(Michael S)
#1
given level of BP lowering) the relative reduction in stroke and
CHD is constant whatever the starting level of BP. Thus, the
absolute benefit from BP lowering depends on the initial level of
risk. A threshold cardiovascular eventrisk of 2% per year has been
advocated by some^1 and equates to treating 40 individuals for five
years to save one cardiovascular event (myocardial infarction,
stroke, angina or cardiovascular death).
Young patients
Since age is a major determinant of absolute risk, treatment
thresholds based on absolute risk levels will tend to postpone
treatment to older ages. However, younger patients with elevated
BP who have a low absolute risk of stroke and CHD exhibit
greatly elevated relative risksof these events compared to their
normotensive age-matched peers. Deciding on the optimal age of
treatment in such individuals presents some difficulty and the
correct strategy has yet to be determined.
Elderly patients
The absolute risk of CHD and stroke in elderly hypertensive
patients is high and, consequently, the absolute benefit from
treatment is much greater than in younger patients. Decisions to
treat based on absolute risk are therefore usually straightforward.
However, there is little in the way of firm trial evidence for the
benefits of treatment in individuals aged more than 80. In these
patients, decisions could be made on a case-by-case basis taking
into account biological age.
What to aim for
Although it might be assumed that the lower the BP the lower
the risk of stroke and CHD, some studies have described a J-
shaped relationship between BP and cardiovascular events,
where the risk of an adverse outcome rises slightly at the lower
end of the BP range. However, in the large Hypertension Optimal
Treatment (HOT) study^3 lowering BP to 130–140/80–85 mmHg
was safe. While there was no additional advantage of lowering
BP below these levels (except possibly in diabetic subjects),
there was also no evidence of a J-shaped phenomenon in this
large trial.
