• when sustained BP exceeds 160/100 mmHg or
• when BP is in the range 140-159/90-99 mmHg and there is evidence of target organ damage, cardiovascular disease or a 10-year CHD risk over 15% or
• for diabetics when BP exceeds 140/90 mmHg.
The optimal target is to lower BP to or below 140/85 mmHg in nondiabetics and 140/80 mmHg in diabetics. The World Health Organization/ International Society for Hypertension sets a more rigorous target of 130/85 mmHg.
Effective treatment reduces the risk of all complications: strokes and myocardial infarction, but also heart failure, renal failure, and possibly dementia. It is easier in individual trials to demonstrate the benefits of treatment in preventing stroke, because the curve relating risk of stroke to blood pressure is almost twice as steep as that for myocardial infarction. What this tells us is not that the relative risk of myocardial infarction due to hypertension is irreversible but that substantial reduction in the absolute risk of myocardial infarction needs attention to hypercholesterolaemia as well as hypertension.31
30 The British Hypertension Society Guidelines are available in summary form in the BMJ 1999 319: 630-635 or online at http:/ / www.bhsoc.org
31 Relative risk refers to the increased likelihood of a patient having a complication compared to a normotensive patient of the same age and gender. Absolute risk refers to the number of patients out of 100, with the same age, gender and blood pressure, predicted to have a complication of the next 10 years.
Treatment will almost always be lifelong for essential hypertension, since discontinuation of therapy leads to prompt restoration of pretreatment blood pressures. If it does not, one should suspect the original diagnosis of hypertension, which should not be made unless blood pressure is elevated on at least three occasions over 3 months.
The relative risks of hypertension and the benefits of treating the condition in the elderly are less than in those under 65s, but the absolute risks and benefits are greater. Given the large choice of treatments available, doctors cannot cite improved quality of life as an excuse for not treating hypertension in the elderly. Starting doses, however, should often be halved and, pending further evidence, less challenging targets for blood pressure reduction may be acceptable.
It is obvious that adverse effects of therapy are important in that very large numbers of patients must be treated so that a few may gain; this is a salient feature of the use of drugs to prevent disease.
Was this article helpful?