Primary prevention to reduce the incidence of stroke should be targeted at the whole population and groups that are at increased risk by increasing awareness and promoting healthy lifestyles that reduce the risk factors for stroke.
The brain's functions depend on a constant blood supply for the oxygen and nutrients needed by its cells. The restriction or stoppage of this supply leads to damage, and possibly death of the brain cells.
A stroke, which is also called a cerebrovascular accident (CVA), is a condition in which the blood supply to a part of the brain is cut off. It is a medical emergency and the earlier treatment is provided, the less likely will be the damage.
Strokes are the third most common cause of death in Malaysia. It is estimated that there are about 52,000 strokes per annum (i.e. every hour, six people experience a stroke).
The risk for recurrent vascular events after a stroke or transient ischaemic attack (TIA) is about 5 per cent per year for stroke, 3 per cent per year for heart attack, and 7 per cent per year for any one of stroke, heart attack or vascular death. The risks are higher in patients who are at an increased risk of CVA or who have carotid stenosis.
It has been estimated that without treatment, the likelihood is one in 10 that a stroke will occur within a month after a TIA.
As strokes lead to disability and even death in some instances, TIAs should be treated as seriously as strokes.
A risk factor increases the chances of getting or having a certain health condition. Some risk factors for stroke cannot be changed, but others can be prevented. Changing risk factors over which a person has control will assist in achieving a longer and healthier life.
Strokes are preventable as lifestyle changes can reduce many of the risk factors. However, there are some risk factors that are not preventable. They include:
The risks are increased in the older person, although about a quarter of strokes occur in the young. The risk doubles in each successive decade after 55 years of age.
The risks are increased in males (except in older adults, when it evens out).
The risks are increased in Indians and Malays because the incidence of diabetes and hypertension are higher in these groups.
4. Medical history
The risks are increased if one has had a heart attack, stroke or TIA. The risks are also increased in pregnancy, abnormal heart beats, chronic renal disease, cancer, some types of arthritis, and in those with abnormal blood vessels or weakness in the wall of an artery.
5. Family history
The risks are increased if a close relative has had a stroke.
Primary prevention is vital in any programme to reduce the incidence of stroke. This should be targeted at the whole population and groups that are at increased risk by increasing awareness and promoting healthy lifestyles that reduce the risk factors for stroke.
Secondary prevention are measures used to prevent recurrence of a stroke. They are individualised depending on the person's pathogenesis based on neuroimaging and other investigations.
The prevention of stroke is similar to the prevention of coronary heart disease.
High blood pressure
High blood pressure (hypertension) is a major risk factor for stroke. The incidence increases in proportion to both the systolic and diastolic blood pressures. Isolated systolic hypertension (systolic blood pressure of more than 160mm Hg and diastolic blood pressure of less than 90mm Hg) is an important risk factor for senior citizens.
A reduction in blood pressure reduces the incidence of stroke. A reduction of the systolic blood pressure by 10mm Hg is associated with a reduction in risk of stroke by about a third, regardless of the baseline blood pressure levels.
Hypertension is controlled by diet, exercise and medicines.
There is an association between raised blood lipids and risk of ischaemic stroke. Hyperlipidaemia is controlled by diet, exercise and medicines.
The use of statins in those at increased risk, e.g. those with cardiovascular disease, diabetes, reduces the incidence of coronary events and ischaemic strokes even in individuals whose blood cholesterol levels are normal (less than 5.0mmol/L).
Diabetes increases the risk of ischaemic stroke by 1.8 to 6 times. The incidence of stroke is significantly reduced by stringent control of hypertension in diabetics.
Scientific studies have indicated that strict control of the blood glucose (Hb A1c less than 6 per cent) is critical.
Diabetes is controlled by diet, exercise and medicines.
Foods rich in fat lead to fatty deposits in the artery walls. The overweight are at risk of hypertension. A low-fat, high-fibre diet, which includes abundant fruits and vegetables (at least five servings daily), is recommended.
Unsaturated fats which increase the blood cholesterol, e.g. meat, ghee, lard, should be avoided. However, a balanced diet has to include some unsaturated fat like fish, olive and vegetable oils.
The daily intake of salt should not be more than 6gm (0.2 oz), which is about one teaspoonful.
A combination of a healthy diet with regular exercise is the best method to maintain a healthy weight, which reduces the risk of developing hypertension.
Regular exercise ensures that the heart and circulation are efficient, keeps the blood pressure normal, and lowers the blood cholesterol.
The recommendation is that there be at least 150 minutes of exercise of moderate intensity, e.g. fast walking, per week (about 30 minutes daily).
A person who has had a stroke should discuss with his healthcare provider about possible exercise plans. It may not be possible to have regular exercise immediately after a stroke, but exercise should begin when there has been progress with stroke rehabilitation.
It is essential that weight be maintained at healthy levels. Many people go on weight reduction programmes only to find that they gain back the kilogrammes they lost. It would be better to accept a steady rate of weight loss instead of overnight success.
Programmes that promise an ideal weight within a short period of time do not usually work out in the long term. The key to keeping the weight loss is to make changes to diet and lifestyle that one can live with. One has to adhere to these changes for life; they have to be part and parcel of everyday life.
Both active and passive smoking increase the risk of stroke. Smoking doubles the risk as it leads to narrowing of the arteries and increases the likelihood of the blood clotting.
Smoking cessation can reduce the risk of a stroke by up to half. In addition, it will also improve general health and reduce the risk of developing other serious conditions like heart disease and lung cancer.
Smokers who have stopped for more than five years have the same risk of stroke as non-smokers.
Heavy alcohol consumption increases the risk of stroke by three times as it can lead to high blood pressure and irregular heart beats, which are both major risk factors for stroke. In addition, alcohol causes weight gain because they are high-calorie compounds.
Consumption of more than three units a day (one unit = one glass of wine = a peg of hard liquor) increases the risk while light or moderate alcohol intake protects against all strokes.
Aspirin has been reported to be of benefit to women aged 65 years or more in the primary prevention of stroke due to its blood thinning effects.
There is substantial evidence of the benefits of aspirin in secondary prevention of recurrent strokes, with a 25 per cent reduction in risk in all patients with strokes who have received aspirin.
When given within 48 hours of a stroke, it has also been beneficial in reducing recurrent strokes and death.
Other anti-platelet medicines
Alternative antiplatelet medicines are prescribed in patients intolerant or allergic to aspirin, have contraindications to aspirin, or when aspirin has failed. The medicines include ticlopidine and clopidogrel.
It is essential to take aspirin or other anti-platelet medicines under the supervision of a doctor. In addition, one should take measures to avoid falls or tripping when taking these blood-thinning medicines.
In a nutshell
There are several measures that can be taken to prevent a stroke or a recurrent stroke, if one has had a stroke. The following will reduce the likelihood of a stroke or recurrent stroke:
>> Control high blood pressure through diet, exercise, and medicines, when necessary.
>> Control diabetes through diet, exercise, and medicines, when necessary.
>> Control raised cholesterol through diet, exercise, and medicines, when necessary.
>> Exercise at least 30 minutes a day.
>> Maintain a healthy weight by eating healthy foods, eating less, and joining a weight reduction programme, if necessary.
>> Do not smoke, or stop smoking. Limit alcohol consumption to one drink a day for women and two a day for men.
>> Avoid illicit drugs. Have regular medical checks and consultations with the family doctor or physician.
Dr Milton Lum is a member of the board of Medical Defence Malaysia.