IT'S USUALLY JUST in urban legends that you hear of a patient going to see their doctor for a runny nose, only to discover an unrelated ailment that - if untreated - could have killed them in five years.
Yet a recent survey of private clinics has shown that when it comes to one medical condition in particular, up to half of all sufferers are oblivious to their state, and risk serious complications unless properly treated. It's not by chance that hypertension, or high blood pressure, is called a 'silent killer'.
In Hong Kong the number of sufferers is rising, but awareness is lagging, according to doctors.
Six years ago, an estimated 5 per cent of the population was believed to be suffering from hypertension. More recent studies suggest the figure is much higher.
For example, a Hospital Authority survey in 2004 found nearly a quarter of people above the age of 40 had high blood pressure, while the incidence among the 25 to 34 age group was double the figure it was in 1999. In the US, where hypertension checks have become one of the top three reasons for a visit to the doctor, one in three people are affected.
For those with hypertension, the heart has to work a lot harder to pump blood around the body. If your blood pressure is high, in the long term you run the risk of a heart attack or stroke, says Andy Chan Wai-kwong, a council member of the Hong Kong Primary Care Foundation.
Although blood pressure rises and falls during the day, sustained high levels are dangerous because the heart works too hard and contributes to a hardening of the arteries. If the heart cannot get enough oxygen-carrying blood, a heart attack can result.
High blood pressure also can result in other problems, such as congestive heart failure, kidney disease and blindness. 'If you leave it untreated for years, it will cause damage to the vital organs such as the brain or heart,' says Chan.
In March, he was involved in a project to measure private doctors' attitudes towards hypertensive patients. The results were published in last month's edition of the Hong Kong Medical Journal.
Of 225 doctors in private practice who were surveyed, 28 per cent said they found more than 30 per cent of patients were previously undiagnosed as being hypertensive. However, it's likely that, if the public sector was included, the figure would be much higher. Global estimates put the level of those undiagnosed as high as 50 per cent.
There are no known causes for high blood pressure, nor any symptoms. 'Around 90 per cent of patients do not have a definite cause for hypertension,' says Chan, although it's speculated that there may be some genetic element in it. The good news is that it's treatable - if caught in time.
Chan is in favour of all new patients being tested for high blood pressure when they visit a doctor. In the study last year, however, only 24.4 per cent of private doctors polled said they tested all new patients aged 18 and above. Nearly 73 per cent of the doctors said they measured blood pressure in some new patients.
The majority of doctors polled said they felt the level of awareness about hypertension among the public was insufficient. According to Gabriel Leung of Hong Kong University's department of community medicine, one factor may be the lack of a core target group. 'Compared to breast cancer, it doesn't have the sort of emotive element attached to it. It doesn't affect any particular interest group ... that's because it's so pervasive,' he says.
Hong Kong consumer habits may also play a role in a lack of awareness about the ailment, he says.
Unlike some western countries, Hong Kong doesn't have a real primary care family doctor system. As hypertension is diagnosed opportunistically, this requires patients to have a doctor who tests them during regular visits. Diagnosis is made after a number of readings, requiring more than one visit.
But Leung says people shouldn't go to their doctors solely for a blood pressure test. 'I wouldn't go specifically for that reason ... I'd recommend everyone finds a family doctor who they go and see as a first contact ... rather than shop around. At every visit, have it measured as a matter of course.'
People should have their blood pressure taken at least once a year, he says, particularly those aged 40 and above. In terms of prevention, the focus is more on generic health habits. It usually takes five to 10 years between having hypertension and the onset of a heart attack or stroke. 'It's all the classic things: eat responsibly and in a healthy way, and exercise,' says Leung.
A poor diet and lifestyle will aggravate the condition or cause it to appear earlier, says Chan. Populations with low sodium diets have been found to have a lower prevalence of hypertension.
Dietitian Sylvia Lam See-way says the average intake of sodium as recommended by the American Heart Foundation is 4-5g per day, the equivalent of one teaspoon of salt.
However, Hong Kong lifestyles make it hard to measure. 'It's very difficult to control if you eat out often,' she says. For example, sauces and traditional Chinese dishes are often packed with sodium.
She also recommends hypertensive patients include more potassium in their diets - as found in fresh fruit and vegetables - as well as calcium. Excess weight is a danger. She recommends patients who are hypertensive and have weight problems to shed up to 10 per cent of their weight to lower blood pressure.
Cardiology specialist Godwin Leung Tat-chi says regular physical activity has been shown to be effective in reducing the risk of developing hypertension by up to 30 per cent, and is advocated as a preventive measure.
Leung says exercise can keep blood vessels free from narrowing, which is the main cause of heart attacks.
'Although the heart is a pump made of muscles, it can't be exercised directly,' he says. 'It can only be exercised through the larger muscle groups, particularly the leg muscles. That's why brisk walking, running, cycling, swimming and jogging are so beneficial.'