Hypertension - A Silent Killer
Hypertension is actually very common among adults in Hong Kong, but many do not realise they have the disease. A study by the School of Public Health of the University of Hong Kong in 2012 revealed that about 1 in 3 adults in Hong Kong has hypertension, and half of the affected did not know about it. In other words, about 1 in 6 persons in Hong Kong has hypertension without knowing it. Among those ever diagnosed with hypertension, 70% were prescribed antihypertensive medication, but only about 40% of this treated group attained good control of blood pressure. The study confirmed the well-known “rule of halves” in hypertension –
- roughly only half of all hypertensive cases are diagnosed,
- half of those diagnosed are treated, and
- half of those treated are well controlled.
Definition of Hypertension
Hypertension, or high blood pressure, is a chronic disease. It occurs when the pressure exerted on the walls of arteries is persistently elevated. About 90% of all patients with hypertension are of unknown causes. This type of hypertension is called “primary hypertension” (or “essential hypertension”) and is probably related to hereditary factors. It usually presents itself after middle age. The remaining 10% patients have the disease because of other diseases, such as kidney diseases or endocrine disorders. This type of hypertension is called “secondary hypertension”.
Criteria of diagnosing hypertension
The criteria of diagnosing hypertension for adults and children are different.
- An adult is said to have hypertension if his systolic blood pressure (SBP) is persistently ≥ 140 millimetres of mercury (mmHg) or diastolic blood pressure (DBP) is persistently ≥ 90 mmHg. Typically, an adult should keep his SBP and DBP below 120 mmHg and 80 mmHg respectively. SBP between 120 mmHg and 139 mmHg or DBP between 80 mmHg and 89 mmHg is considered pre-hypertension. People with pre-hypertension are advised to have their blood pressure rechecked within one year.
- A child or adolescent is said to have hypertension if the SBP or DBP is ≥ 95th percentile for age, height and gender on repeated measurements.
How do I know if I have hypertension
- While a small number of patients may suffer from headache, dizziness and fatigue, many people with hypertension for years are not aware of it because hypertension typically does not give rise to symptoms. If hypertension goes untreated or if it is not well controlled, it will damage the arteries and vital organs, in turn leading to serious complications like coronary heart disease, stroke, retinal disease, kidney failure, etc. As the first presenting symptom can be stroke or heart attack, this is why hypertension is often called the “silent killer”.
- Getting regular, accurate blood pressure readings is thus essential for early detection of the problem. Adults aged 18 years or above should have their blood pressure checked at least once every two years. More frequent blood pressure monitoring may be required according to the blood pressure level, age, overall cardiovascular risk profile, and medical advice.
- That being said, occasional elevation of blood pressure above the normal range may not be hypertension, since this can be the body’s normal response to stress. If in doubt, seek medical advice.
(March 2013)