High blood pressure Hypertension (high blood pressure) is a major risk factor in both ischaemic and haemorrhagic strokes (Wolf and D’Agostino 1993). Welin et al (1987) found that high blood pressure was a risk factor in 789 men, 57 of whom had had a stroke and had been monitored for up to 18 years. Sandercock, Warlow and Jones (1989) studied risk factors in 224 first embolic strokes in an Oxfordshire population of 104,000 and found that high blood pressure was present in 52 per cent of the cases compared with a healthy group.
Studies in developing countries have suggested that high blood pressure is a major risk factor (Akbar and Mushtaq 1999; El Sayed et al 1999). The most common risk factor was hypertension concomitant with diabetes mellitus in 40.4 per cent of hospitalised patients and hypertension alone for 24.9 per cent (El Sayed et al 1999). Akbar and Mushtaq (1999) found that high blood pressure was present in 20 per cent of stroke survivors. However, there were no comparisons with a healthy group in these two studies, making it difficult to draw conclusions from them.
Cigarette smoking Several studies have shown that cigarette smoking is a major risk factor for stroke (Shaper et al 1991; Wannamethee et al 1995; Wishant, 1997) In a population of 7,735 British men monitored for eight years, cigarette smoking was found to be associated with a risk of having a stroke (Shaper et al 1991). Shinton and Beevers (1989) found that cigarette smoking increased the risk of cerebral infarction among smokers compared to non-smokers. However, the risk of stroke disappeared two to four years after stopping smoking (Kawachi, Colditz and Stampfer 1993). In the only study in Saudi Arabia, El Sayed et al (1999) found that 1.8 per cent of stroke survivors who been admitted to hospital were smokers, although these results should be carefully interpreted because there were no comparisons between smokers and non-smokers.
Diabetes Several studies have shown that diabetes is another major stroke risk factor (Burchfield, Curb and Rodrigues 1994; United Kingdom Prospective Diabetes Study Group 1998). Among Japanese living in the USA, those with diabetes had twice the risk of an embolic stroke of non-diabetic subjects (Burchfield, Curb and Rodrigues 1994). In the Arab population one-fifth of stroke survivors were found to suffer from diabetes (Al-Jishi and Mohan 1999; Al-Rajeh et al 1993a, Al-Rajeh et al 1998; El Sayed et al 1999).
Atrial fibrillation Irregular heart beat (atrial fibrillation) is another risk factor associated with stroke (Goldstein 1998). Benjamin et al (1998) found that there was a dramatic increase in the risk of strokes, which increased with age, associated with atrial fibrillation. The risk factors increased from 1.5 per cent for those aged between 55 and 59 to 23 per cent for those aged between 80 and 89.
In a few studies carried out in developing countries, atrial fibrillation was found to be present in around 5 to10 per cent of stroke patients admitted to hospital (Akbar and Mushtaq 1999; Al-Rajeh et al 1993b; El Sayed et al 1995).
Hyperlipidaemia Hyperlipidaemia (raised cholesterol levels) is another factor associated with the risk of stroke (Goldstein 1998). It is well documented that lipid abnormalities are associated with coronary artery disease but there is very little research into the relationship between lipid abnormalities and cerebrovascular diseases, including strokes. In a review of 45 papers Qizilbash et al (1998) reported that there was no association between cholesterol level and haemorrhagic stroke. Other studies have looked at the relationship between cholesterol levels and ischaemic stroke and found a weak association (Benfante et al 1994).