The management of the elderly with hypertension.

Abstract

JRAAS 2001;2:11–3 Although much effort is spent in trying to define hypertension by identifying a level of blood pressure (BP) above which subjects are at increased risk,hypertension is best defined as the level of BP above which treatment does more good than harm. This information cannot come from epidemiological or clinical observations,but from the results of randomised controlled trials. At the beginning of year 2001, we know that, at ages up to the late seventies, it is worth treating a systolic blood pressure (SBP) >160 mmHg and/or a diastolic blood pressure (DBP) ≥90 mmHg. A randomised controlled trial assesses outcome in at least two equivalent groups. In the traditional comparison of active hypertensive treatment with placebo, the only difference between the active and placebo-treated groups is the treatment. In observational studies, any benefits from active treatment may be due to selection of subjects with confounding factors, such as high social class, low blood sugars and cholesterol, a tendency to take exercise, not to smoke nor to drink alcohol in excess. Although the randomisation trials tell us when to treat, we do not know the lowest level of BP at which treatment confers an overall benefit. It is unlikely that those with low levels of BP would benefit, as few would gain by having cardiovascular events prevented, yet all are at risk of the adverse effects of treatment. While awaiting trial results, there is speculation that treatment should be started at, say, a systolic pressure of 140–159 mmHg. Even if this is true, adverse effects may outweigh advantages in certain groups, for example the very elderly (over 80 years) and those whose BP is high when lying but low on standing. Adverse consequences may also apply to those with a high BP when first seen but normal pressures thereafter and those who always have a high BP in the clinic but not outside (white coat hypertensives). The benefit: risk comparison for those over the age of 80 and for those with postural hypotension, is not yet known and the problem of the over 80s is considered later in this editorial. Transient hypertension, at least in men, appears to confer an excess cardiovascular risk although this risk may not be reversible with treatment,a problem that was examined in the Syst-Eur trial. In this trial of 4695 patients, followed for an average of two years,717 had ambulatory BP monitoring at baseline. All patients were over the age of 60, had isolated systolic hypertension, with systolic pressure in the clinic of more than 160 mmHg, and their standing SBP had to be more than 140 mmHg. They were divided into three groups according to the average ambulatory daytime systolic pressure of ≥160 mmHg,140–159 mmHg and <140 mmHg, and the reduction in cardiovascular events was 50%, 20% and 60% in the three groups, respectively. Events were few in the low pressure group and the 60% reduction did not achieve statistical significance. However, the 50% reduction in the high pressure group approached statistical significance and this group had a 70% reduction in stroke incidence with active treatment (p=0.03).These data provide some evidence to support the concept that the higher the sustained levels of BP, the greater the benefits of active treatment and presumably the more favourable benefit: risk comparison. We need to determine the sustained level of BP. At age 65–79 years, randomised trials have shown that a sustained systolic pressure ≥160 mmHg should be treated, irrespective of DBP. It is also probable (but not proven) that a diastolic pressure of ≥90 mmHg should be treated, irrespective of systolic pressure. The pressure should be measured at least three times on separate occasions over a period of time. The period of time should be at least two months, to agree with the evidence from the trials, and the BP should be taken in the sitting position but with a standing systolic pressure of at least 140 mmHg. Thus, we have an evidence base for treatment in subjects under age 80, but, having decided on ‘treatment’, what should this be and what target BP should we aim for?