DUBBED the silent killer, sadly many are unaware of their high blood pressure until affected by a significant complication like heart attack or stroke, which can cause significant physical disability and long lasting psychological problems.

Presently, the management of raised blood pressure, or hypertension to use its medical terminology, has focussed on people either with persistently elevated readings, or with borderline high numbers and other risk factors for cardiovascular disease, such as diabetes and kidney conditions.

However new research, looking at just under 350,000 individuals in 48 studies, has shown that irrespective of whether a person has risk factors, they may benefit from antihypertensive treatments, even at normal blood pressure levels.

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The study, published in the Lancet, demonstrated that for every 5 mmHg (millimetre of mercury) reduction in systolic blood pressure (the top reading), cardiovascular complications, including heart attack, heart failure and stroke went down by between 5 and 13 per cent.

Blood pressure is recorded as two numbers in millimetres of mercury. The top number, or systolic, measures the pressure in your arteries as the heart contracts (systole). The bottom figure, or diastolic, represents the resting tone of the arterial system, when the heart is relaxed (diastole). Both numbers are important.

Current advice is to have your blood pressure checked at least once every five years after the age of 40. However high blood pressure may occur before this age. It is more common in those with diabetes, kidney disease and in some ethnic minorities.

If left untreated, hypertension puts strain on the heart which may cause heart failure. The increased pressure in blood vessels damages the lining either causing narrowing, or the vessel to actually tear. If this is a coronary artery a heart attack will occur, in the eye it may lead to blindness. In the brain a stroke will be the result and any organ of the body can be affected.

Contrary to popular belief, hypertension is notoriously without symptoms. Most headaches and nose bleeds are not a sign of raised blood pressure. It may only cause you to feel unwell at extremely high levels, by which time the arteries will have been under considerable strain.

It makes sense to know your numbers, if you are over 40, or under 40 and with risk factors for the development of raised blood pressure.