Last reviewed 05/2021
Primary or essential hypertension refers to hypertension without demonstrable cause. It accounts for 95% of all cases of hypertension and is a diagnosis of exclusion.
Blood pressure is normally distributed in the population and there is no natural cut-off point above which 'hypertension' definitively exists and below which it does not
- risk associated with increasing blood pressure is continuous, with each 2 mmHg rise in systolic blood pressure associated with a 7% increased risk of mortality from ischaemic heart disease and a 10% increased risk of mortality from stroke
- diastolic pressure is more commonly elevated in people younger than 50. With ageing, systolic hypertension becomes a more significant problem, as a result of progressive stiffening and loss of compliance of larger arteries
- at least one quarter of adults (and more than half of those older than 60) have high blood pressure.
NICE have classified hypertension as:
This guidance uses ambulatory or home monitoring to confirm stage 1 or stage 2 hypertension.
Stage 1 hypertension
- clinic blood pressure is 140/90 mmHg or higher AND
- subsequently Ambulatory blood pressure monitoring (ABPM) daytime average OR Home blood pressure monitoring (HBPM) average blood pressure is 135/85 mmHg or higher.
Stage 2 hypertension
- clinic blood pressure is 160/100 mmHg or higher AND
- subsequently ABPM daytime average or HBPM average blood pressure is 150/95 mmHg higher.
- clinic systolic blood pressure is 180 mmHg or higher or clinic diastolic blood pressure is 110 mmHg or higher
- the diagnosis of hypertension should not be made on the basis of a single elevated reading. In many cases, a second blood pressure reading is lower, and often, a third lower still
- patients found to have malignant or accelerated phase hypertension should be referred to hospital as an emergency
- the majority of patients will have essential hypertension but it is nevertheless imperative to fully investigate for secondary causes
- assessment should also consider other risk factors for cardiovascular disease and stroke