Conference Report

Shah Ebrahim, Editor

World Stroke Congress

The global burden of stroke is huge: it is the third-ranked cause of death, affects 5.5 million people a year, and is responsible for 50 million disability adjusted life years (DALYs). Over the next 20 years, stroke will rise from 7th in the DALY league table to 4th, influenced largely by the ageing of populations in less economically developed countries. However, as acknowledged by Colin Mathers, World Health Organization global burden of disease project, these estimates are based on mortality statistics covering only 34% of the world's population and extremely patchy disability data. Ruth Bonita, World Health Organization non-communicable disease surveillance section, said that a major priority was to improve stroke surveillance in a stepwise fashion, starting with cardiovascular risk factor surveys and hospital registration of strokes, and moving towards more comprehensive stroke registers covering both urban and rural populations.

The decline in stroke mortality in many countries of the world, and its rise in some central and eastern European countries is unexplained by changes in risk factors and only limited secular trend data on incidence are available. Consequently, new data on stroke incidence and case-fatality from MONICA sites are of considerable interest. Case fatality at 28 days varies from 15% to 50% with most of the variation attributable to 7–28 day events rather than early brain deaths occurring in the first week. In countries with a declining mortality trend, it is estimated that about two-thirds of the change is explained by falls in case-fatality and the remainder by incidence rate changes. In countries that are experiencing rises in stroke mortality, all the change is attributable to increases in 28 day case-fatality. These findings, if generalizable to non-MONICA settings, are of profound importance, suggesting that medical care may have a greater effect on population stroke burden than we currently suppose. Moreover, with population ageing, even if stroke incidence stays the same, the numbers of stroke patients requiring medical care will rise dramatically over the next two decades. Mortality rates do not appear to be a proxy for incidence.

By contrast, the Northern Manhattan Stroke Study, examining the greater mortality among black and Hispanic Americans compared with whites, found similar case-fatality between ethnic groups and concluded that mortality differences reflected incidence differences. A review of stroke in sub-Saharan Africa demonstrated how little is known about a condition that appears to be an increasing cause of hospital admission. Without adequate registration of non-communicable diseases in less economically developed countries it does seem that public health policy and practice will remain weak. A clear consensus is emerging amongst the scientific community that better surveillance systems are needed. The next step is for scientists to persuade governments of these countries to request the technical support required which will give the World Health Organisation a mandate to initiate new programmes which will increase our understanding of how best to prevent stroke in the developing world.

Attempts to examine aetiological hypotheses were marred by poor study design. A study examining the risk associated with raised serum cholesterol managed to avoid a controlled comparison. A study of stroke risk associated with H. pylori, subjected patients to an unneeded (and probably unethical) endoscopy, and compared serum levels of Helicobacter pylori IgG antibodies with controls suffering gastro-intestinal symptoms. Perhaps not surprisingly, no increased risk of stroke was found in those with high H. pylori levels. And a study demonstrating endothelial dysfunction in ischaemic stroke patients without risk factors failed to recognise that for continuously distributed risk factors, there is no level commensurate with ‘no risk’. No new gene polymorphisms appeared to be important in stroke: neither the alpha or beta fibrinogen gene polymorphisms were related to carotid stenosis, nor was a SNP in the beta-2 glycoprotein 1 gene relevant in cerebral infarction. The ‘hot’ poster topic was a Japanese study examining haemorrhagic strokes occurring after sexual intercourse—just over half were associated with sex in extramarital relationships.

The major thrusts in stroke trials that will provide evidence to test aetiological hypotheses were studies of statins (PROSPER, RESPECT trials) and B6, B12 and folate (VITATOPS trial) in secondary prevention of stroke. Acute trials, while increasing in sample size, are still failing to find a safe neuroprotective agent. The Third International Stroke trial (the first examined the role of aspirin and heparin in acute stroke, the second is examining feeding regimens) has been established to test whether intravenous thrombolysis could be more widely used.

The 4th World Stroke Congress received 1300 delegates from 64 countries, and covered an extensive range of topics from basic science to rehabilitation. The meeting was weak in aetiological epidemiology and practical public health interventions, but provided a strong platform for reinforcing the need to have good data on stroke burdens as a prerequisite for public health. The National Stroke Foundation of Australia (http://www.strokefoundation.com.au) organized a meeting of national stroke associations at the start of the Congress with the aim of establishing a World Stroke Association which would aim to improve awareness of stroke, raise standards of prevention and care, and help establish national stroke associations in those countries without such bodies. This initiative deserves support as it will provide a means by which the burden of stroke may be reduced.

Notes

25–29 November 2000 in Melbourne, Australia





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