Claiming Stroke Incidence to be Largely Preventable

Researchers suggest, from an examination of epidemiological data, that stroke is for most patients a preventable occurrence largely driven by hypertension, inactivity, and obesity. In this the implication is that better life choices in the environment of present day medical technologies could push stroke to occur at greater ages, such that most older people would die from other consequences of aging first - more a matter of postponement than prevention per se. Lowering age-related increases in blood pressure is known to lower the risk of all cardiovascular issues, and the effects of inactivity and obesity on life expectancy and risk of age-related disease are well proven. Hypertension is driven by stiffening of blood vessels, which is caused at root by fundamental damage processes such as cross-linking in blood vessel walls, inflammation due to the presence of senescent cells, and so forth. The bad life choices mentioned above will speed up stiffening in blood vessels and consequent hypertension, but this end state will still exist, further down the line, even for those people who live the healthiest lives. This will continue to be the case until new therapies are built to repair the root causes - which should in my opinion be the highest priority, over and above campaigns aimed at adjusting behavior.

Hypertension (high blood pressure) remains the single most important modifiable risk factor for stroke, and the impact of hypertension and nine other risk factors together account for 90% of all strokes, according to an analysis of nearly 27,000 people from every continent in the world. Stroke is a leading cause of death and disability, particularly in low-income and middle-income countries. The two major types of stroke include ischaemic stroke (caused by blood clots), which accounts for 85% of strokes, and haemorrhagic stroke (bleeding in the brain), which accounts for 15% of strokes. Prevention of stroke is a major public health priority, but needs to be based on a clear understanding of the key preventable causes of stroke. This study builds on preliminary findings from the first phase of the INTERSTROKE study, which identified ten modifiable risk factors for stroke in 6,000 participants from 22 countries. The full-scale INTERSTROKE study included an additional 20,000 individuals from 32 countries in Europe, Asia, America, Africa and Australia, and sought to identify the main causes of stroke in diverse populations, young and old, men and women, and within subtypes of stroke.

To estimate the proportion of strokes caused by specific risk factors, the investigators calculated the population attributable risk for each factor (PAR; an estimate of the overall disease burden that could be reduced if an individual risk factor were eliminated). The PAR was 47.9% for hypertension, 35.8% for physical inactivity, 23.2% for poor diet, 18.6% for obesity, 12.4% for smoking, 9.1% for cardiac (heart) causes, 3.9% for diabetes, 5.8% for alcohol intake, 5.8% for stress, and 26.8% for lipids (the study used apolipoproteins, which was found to be a better predictor of stroke than total cholesterol). Many of these risk factors are known to also be associated with each other (e.g. obesity and diabetes), and when combined together, the total PAR for all ten risk factors was 90.7%, which was similar in all regions, age groups and in men and women.


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