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National Research Project



Unit of Biostatistics, Epidemiology and Public Health’ investigators involved:
Giovanni Corrao
Department of Statistics
and Quantitative Methods
University of Milano-Bicocca
Via Bicocca degli Arcimboldi 8,
U7,20126 Milan, Italy
E-mail: [email protected]

Stroke is one of the major causes not only of mortality, but of disease burden worldwide , because of residual disability and cognitive decline. In the European Union stroke is the second cause of mortality (10.9%) immediately after coronary heart disease (18.1%), accounting for approximately 200,000 deaths yearly. In China stroke is the second leading cause of mortality with the proportion of haemorrhagic stroke in total stroke much higher than in the Western world and the burden of stroke became higher in less-developed but more populous rural areas than in urban areas since later 1990s.

In Europe stroke also accounts for 5.27% of the total burden of illness, but because of aging of the population it has been calculated that, by the year 2020, stroke will account for 6.2% of the total illness burden (1). Some degree of disability occurs quite frequently after stroke: among patients above the age of 65 years and surviving a stroke, 50% have some residual hemiparesis, 30% are unable to walk without assistance, 26% are dependent on others for help with daily living, 19% have aphasia, 35% depressive symptoms and 26% are being cared for in a nursing home.

Although stroke mortality is high, the majority of stroke patients survive, and are at high risk of stroke recurrences as well as incidence of other cardiovascular events, such as myocardial infarction.

Indeed, stroke recurrences account for 15-20% of all strokes.

Also a transient ischaemic attack (TIA) often heralds occurrence of a stroke, and it has recently been reported that up to 40% (average 20%) of strokes are actually preceded by a TIA. Therefore, the population of patients with a history of stroke or TIA is large, and secondary prevention of stroke is of the greatest importance. Prevention is also the best way to decrease the burden of stroke because current treatments of acute stroke are limited. A better prevention of stroke and stroke recurrence has obvious social and economic implications.

In 2004 in the United States the estimated direct and indirect costs for stroke amounted to $53.6 billion, and in the United Kingdom it has been calculated that 6% of all health service costs are attributed to stroke care.

Role of antihypertensive therapy: solved and unresolved issues

Prevention of stroke, as well as of stroke recurrence, is substantially based on blood pressure (BP) lowering treatment. The relation of stroke and stroke mortality with systolic and diastolic blood pressure (SBP, DBP) has been demonstrated in observational studies on more than one million individuals, and is shown to be particularly steep, and steeper than, for example, the relation with coronary heart disease events (CHD).

The results of the INTERSTROKE study, a recent epidemiological survey in 22 countries worldwide (four of which in Europe), have confirmed that hypertension is the most important risk factor for stroke (with a population-attributable risk of over 50%), and more important than other objectively measured risk factors (e.g., lipids and glucose). This epidemiological evidence is paralleled by the demonstration, thanks to a host of placebo-controlled trials, that drug-induced lowering of blood pressure is accompanied by a very substantial and statistically significant reduction in stroke incidence (by about 40%), which is even greater than the significant reductions observed for CHD events, and cardiovascular and all-cause mortality.

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