Smoking and high BP raise stroke risk

Smoking boosts the increased risk of a haemorrhagic stroke already faced by people with high blood pressure (BP). Haemorrhagic stroke, when a blood vessel bursts inside the brain, is an especially debilitating stroke, as about half of the people who have one die as a result of it, while many survivors are left with paralysis or other debilitating effects. And previous research suggests that smoking and high blood pressure — both major risk factors for cardiovascular disease — are the two most common contributing factors of death in the world, contributing to one in five of all deaths. To find out more about this association, researchers studied data of 563,144 people with an average age of 47 years, who were part of 41 studies in the Asia Pacific region. More than one-third of the participants were smokers at the outset. In nearly seven years of follow-up, 746 of the 210,961 smokers and 899 of the 352,183 non-smokers suffered a haemorrhagic stroke. Further analysis revealed that for every 10 mm/Hg increase in systolic (the first out of the two readings) BP, smokers faced an 81 per cent increased risk of haemorrhagic stroke, compared with a 66 per cent increased risk for non-smokers. This added risk of smoking in people with high BP appeared to be specific to haemorrhagic stroke, as there was no evidence to indicate a similar effect on the risk of ischaemic stroke (due to blocked blood flow to the brain) or coronary heart disease. Smoking may further damage blood vessels in the brain that are already weakened by high BP. Weakened blood vessels are prone to rupture and bleeding, thus increasing the risk of haemorrhagic stroke. Smokers with the highest systolic BP readings (150 mmHg or greater) were nine times more likely to suffer haemorrhagic stroke than smokers with the lowest readings (120 mmHg or less). Non-smokers with the highest systolic BP readings were seven times more likely to suffer haemorrhagic stroke than those with the lowest readings. The findings indicate that smoking and high BP both increase the risk of haemorrhagic stroke. Since these two risk factors have a synergistic effect, quitting smoking and BP control together will be more effective in preventing stroke than if these are addressed alone.