Advances in subarachnoid hemorrhage.
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Biomedical subjects
Publications and source records attributed to Valery L Feigin.
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BACKGROUND AND PURPOSE: After a 1996 review from our group on risk factors for subarachnoid hemorrhage (SAH), much new information has become available. This article provides an updated overview of risk factors for SAH. METHODS: An overview of all longitudinal and case-control studies of risk factors for SAH published in English from 1966 through March 2005. We calculated pooled relative risks (RRs) for longitudinal studies and odds ratios (ORs) for case-control studies, both with corresponding 95% CIs. RESULTS: We included 14 longitudinal (5 new) and 23 (12 new) case-control studies. Overall, the studies included 3936 patients with SAH (892 cases in 14 longitudinal studies and 3044 cases in 23 case-control studies) for analysis. Statistically significant risk factors in longitudinal and case-control studies were current smoking (RR, 2.2 [1.3 to 3.6]; OR, 3.1 [2.7 to 3.5]), hypertension (RR, 2.5 [2.0 to 3.1]; OR, 2.6 [2.0 to 3.1]), and excessive alcohol intake (RR, 2.1 [1.5 to 2.8]; OR, 1.5 [1.3 to 1.8]). Nonwhite ethnicity was a less robust risk factor (RR, 1.8 [0.8 to 4.2]; OR, 3.4 [1.0 to 11.9]). Oral contraceptives did not affect the risk (RR, 5.4 [0.7 to 43.5]; OR, 0.8 [0.5 to 1.3]). Risk reductions were found for hormone replacement therapy (RR, 0.6 [0.2 to 1.5]; OR, 0.6 [0.4 to 0.8]), hypercholesterolemia (RR, 0.8 [0.6 to 1.2]; OR, 0.6 [0.4 to 0.9]), and diabetes (RR, 0.3 [0 to 2.2]; OR, 0.7 [0.5 to 0.8]). Data were inconsistent for lean body mass index (RR, 0.3 [0.2 to 0.4]; OR, 1.4 [1.0 to 2.0]) and rigorous exercise (RR, 0.5 [0.3 to 1.0]; OR, 1.2 [1.0 to 1.6]). In the studies included in the review, no other risk factors were available for the meta-analysis. CONCLUSIONS: Smoking, hypertension, and excessive alcohol remain the most important risk factors for SAH. The seemingly protective effects of white ethnicity compared to nonwhite ethnicity, hormone replacement therapy, hypercholesterolemia, and diabetes in the etiology of SAH are uncertain.
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BACKGROUND: The last few years have seen a considerable increase in the amount of information available concerning blood pressure (BP) and stroke associations. This article provides an overview of published reviews of the effects on stroke seen in trials of BP-lowering drugs and compares these with the results available from cohort studies. SUMMARY OF REVIEW: We present a review of major overviews of prospective cohort studies and an updated meta-analysis of >40 randomized controlled trials of BP lowering, which included >188 000 participants and approximately 6800 stroke events. Cohort studies now indicate that in the Asia Pacific region as well as in North America and Western Europe, each 10 mm Hg lower systolic BP is associated with a decrease in risk of approximately one third in subjects aged 60 to 79 years. The association is continuous down to levels of at least 115/75 mm Hg and is consistent across sexes, regions, and stroke subtypes and for fatal and nonfatal events. The proportional association is age dependent but is still a strong and positive association in those aged 80 years. Data from randomized controlled trials, in which mean age at event was approximately 70 years, indicate that a 10 mm Hg reduction in systolic BP is associated with a reduction in risk of stroke of approximately one third. Per mm Hg systolic BP reduction, the benefits for stroke appear similar between agents, by baseline BP levels, and whether or not individuals have a past history of cardiovascular disease. There is, however, evidence of greater benefit with a larger BP reduction. CONCLUSIONS: The epidemiologically expected benefits of BP lowering for stroke risk reduction are broadly consistent across a range of different population subgroups. There are greater benefits from larger BP reductions, and initiating and maintaining BP reduction for stroke prevention is a more important issue than choice of initial agent.
BACKGROUND: The last few years have seen a considerable increase in the amount of information available concerning blood pressure (BP) and stroke associations. This article provides an overview of published reviews of the effects on stroke seen in trials of BP-lowering drugs and compares these with the results available from cohort studies. SUMMARY OF REVIEW: We present a review of major overviews of prospective cohort studies and an updated meta-analysis of >40 randomized controlled trials of BP lowering, which included >188 000 participants and approximately 6800 stroke events. Cohort studies now indicate that in the Asia Pacific region as well as in North America and Western Europe, each 10 mm Hg lower systolic BP is associated with a decrease in risk of stroke of approximately one third in subjects aged 60 to 79 years. The association is continuous down to levels of at least 115/75 mm Hg and is consistent across sexes, regions, and stroke subtypes and for fatal and nonfatal events. The proportional association is age dependent but is still strong and positive in those aged 80 years. Data from randomized controlled trials, in which mean age at event was approximately 70 years, indicate that a 10 mm Hg reduction in systolic BP is associated with a reduction in risk of stroke of approximately one third. Per mm Hg systolic BP reduction, the relative benefits for stroke appear similar between agents, by baseline BP levels, and whether or not individuals have a past history of cardiovascular disease. There is, however, evidence of greater benefit with a larger BP reduction. CONCLUSIONS: The epidemiologically expected benefits of BP lowering for stroke risk reduction are broadly consistent across a range of different population subgroups. There are greater benefits from larger BP reductions, and initiating and maintaining BP reduction for stroke prevention is a more important issue than choice of initial agent.
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This overview of population-based studies of incidence, prevalence, mortality, and case-fatality of stroke was based on studies from 1990. Incidence (first stroke in an individual's lifetime) and prevalence were computed by age, sex, and stroke type. Age-standardised incidence and prevalence with the corresponding 95% CI were plotted for each study to facilitate comparisons. The review shows that the burden of stroke is high and is likely to increase in future decades as a result of demographic and epidemiological transitions in populations. The main features of stroke epidemiology include modest geographical variation in incidence, prevalence, and case-fatality among the--predominantly white--populations studied so far, and a stabilisation or reversal in the declining secular trends in the pre-1990s rates, especially in older people. However, further research that uses the best possible methods to study the incidence, risk factors, and outcome of stroke are urgently needed in other populations of the world, especially in less developed countries where the risk of stroke is high, lifestyles are changing rapidly, and population restructuring is occurring.
Current treatment of acute stroke remains unsatisfactory. This review presents experimental and clinical data which suggest that mild induced hypothermia could be a potent and practicable neuroprotective treatment of acute ischaemic stroke and intracerebral haemorrhage. Hypothermia, if proven to be safe, effective and widely practicable in patients with acute stroke, could have an enormous positive impact on reducing the burden of stroke worldwide. Critical issues that will need to be considered in a well designed randomised controlled trial of induced hypothermia in acute stroke patients are discussed.
As medicine moves into the 21st century, with added pressures of increasing costs and limited resources, successful reduction of the impact of stroke on the population will require shifting our emphasis away from treating end stages of generalized atherosclerosis and other underlying diseases to prevention of these diseases. However, before any potential interventions can be promoted with confidence, more needs to be known about the specific causes of stroke subtypes in various populations, especially potentially modifiable risk factors. In this selective review, we appraise current evidence on some markers of systemic inflammation (C-reactive protein), endothelial dysfunction (homocysteine, von Willebrand factor), dietary fatty acids and micronutrients as risk factors for stroke. Although a great deal of research into the role of these risk factors in cardiovascular diseases has been undertaken, little reliable information is available on their role in stroke, especially in the elderly. Evaluation of plasma fatty acids and specific antioxidants and micronutrients as well as markers of systemic inflammation, endothelial dysfunction (including C-reactive protein, homocysteine levels, von Willebrand factor, and paraoxonase activity) may prove to be valuable in the future determination of the risk of stroke.
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