What is hypertension?

Hypertension is both a disease and a major risk factor for other diseases. Population studies show anincreasing rate of cardiovascular events such as stroke, myocardial infarction, heart failure, atrial fibrillation and premature mortality, with increasing blood pressure (from systolic blood pressures ≥115 mmHg). This relationship is exponential, and stronger for systolic pressure than for diastolic pressure.

Untreated very high (>180/110 mmHg) or rapidly rising blood pressure (such as in eclampsia) can overcome normal microvascular autoregulation. This leads to acute damage in the microcirculation and results in a multisystem clinical syndrome of accelerated or malignant hypertension, or cerebral haemorrhage, which are immediate threats to life.1 Accelerated or malignant hypertension is now fortunately uncommon. The main consideration in the majority of individuals is the relationship between their blood pressure and subsequent risk of cardiovascular disease. Given the continuous relationship of blood pressure to risk, any level of blood pressure used to define ‘hypertension’ will always be arbitrary. The critical issue is, how do we define hypertension, and does it matter?