Clinical update: Hypertension – Twenty years ago, an audit of detection, treatment and control of hypertension in adults in Scotland (Smith et al) found that in half of those men with blood pressure greater than or equal to 160/95 mm Hg, hypertension was undetected (53 per cent).
In half of those in whom it had been detected it remained untreated (42 per cent), and in half of those receiving treatment it was not controlled (50 per cent). This is called the Rule of Halves. In women the numbers were 46 per cent, 33 per cent and 40 per cent respectively.
Thus it was clear that blood pressure needed to be measured and controlled far better, particularly as some patients do not take their medication and revert to their old lifestyles. One of the advantages of a possible hypertension vaccination is that it might overcome problems with compliance.
Angiotensin II vaccination and angiotensin II receptor vaccination are currently being explored. A phase III trial indicates that a vaccine can give two months of blood-pressure lowering. There is not a cost benefit analysis as yet and the effects of repeated vaccination are not known.
Another promising area for inquiry was identified in a recent paper in the New England Journal of Medicine, which showed that an endothelin receptor antagonist (ERA) is useful in resistant hypertension. This is being used in a small number of patients.
Genetics is another area where advances are expected. Experts believe high blood pressure is probably between 30-50 per cent genetic. For example, there are likely to be genetic factors that react to the excess salt load in the modern diet.
Ultimately, it will hopefully be possible to match the correct class of drug to the patient more effectively through the use of genetics. However, the reality is that only about ten different relevant polymorphisms have been found. These account for just 1-2 per cent of the genetic causes of blood pressure variation. Thus there are clearly many more genetic factors awaiting discovery.
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