A new study on risk factors in cardiovascular disease in Asia has found that blood pressure is more strongly related to coronary heart disease and stroke in Asia, as compared with Western countries such as Australia and New Zealand.

A paper from the George Institute for International Health on the outcomes of the study, to be published in the October 2005 issue of the European Journal of Cardiovascular Prevention and Rehabilitation, notes that high blood pressure is a key risk factor for haemorrhagic stroke, which is relatively more common amongst Asian populations. A 10mmHg increase in systolic blood pressure was found to be associated with a 72% greater risk of having a haemorrhagic stroke in Asian groups, compared with 49% in Australia and New Zealand.

Recent data suggest that hypertension (high blood pressure) is higher in many Asian countries than in Australia. For example, around 28% of people in China are estimated to have hypertension, compared with 19% in Australia. In India and Japan, the percentages are higher still.

Prof. Mark Woodward, Director of the Epidemiology and Biostatistics at the George Institute, who authored the paper, explained that "Cardiovascular disease is already the leading cause of death in many Asian populations, but the relationships between risk factors and cardiovascular disease can differ in Asian and Western populations.

"A lack of data in the past has prevented the reliable quantification of such differences, which, if shown to exist, would suggest that different cardiovascular prevention and treatment strategies are required for Asia, as compared to western countries.

"By far the greatest amount of evidence for the treatment and prevention of cardiovascular disease has come from the West, with very limited evidence from Asia. However, Asia is a huge region, where China alone accounts for approximately a fifth of the world's population. If western evidence is to be used as a basis for cardiovascular medicine in Asia, it is crucial to establish that the risk factors act at least in a qualitative sense in Asia just as they do in western populations", said Prof. Woodward.

In Asia, stroke is proportionately more common than in Western countries; in some Asian countries (such as China) stroke is more common than coronary heart disease, the predominant form of cardiovascular disease in the West. Haemorrhagic stroke, which is more likely than ischaemic stroke to be fatal, is proportionately more common in Asia than in western societies.

"By 2020, the annual mortality from cardiovascular disease will reach 25 million and will have the greatest impact on populations from the lower and middle-income countries of the Asia-Pacific region. Identifying regional differences in the strength and nature of the relationships between risk factors and cardiovascular disease mortality may assist in the allocation of limited resources for the primary prevention of cardiovascular disease in countries in which health systems are often severely under-funded and overburdened," Prof. Woodward noted.

"Given that increases in blood pressure were more strongly associated with haemorrhagic stroke and coronary heart disease in Asian populations compared with Australia and New Zealand, population-wide measures to lower blood pressure, such as reducing the consumption of salt, should be of particular benefit in Asian populations", he said.

Epidemiology is the study of risk factors for disease in human populations.

Biostatistics is the branch of statistics related to medical and health applications.

Mark Woodward is Director of the Epidemiology and Biostatistics Division at The George Institute, Professor of Biostatistics at the University of Sydney and Honorary Consultant Epidemiologist at Royal Prince Alfred Hospital. He has a PhD from the Department of Applied Statistics at the University of Reading, UK, where he subsequently worked for several years, most recently as Senior Lecturer in Statistical Epidemiology. Mark holds Honorary Professorships at the University of Glasgow and at Mahidol University in Bangkok, as well as an Honorary Senior Research Fellowship at the Cardiovascular Epidemiology Unit of the University of Dundee. He has previously been the Director of the Institute of Statisticians Training and Development Centre in the UK. Mark has extensive experience working in developing countries and with aid agencies, including the Asian Development Bank, the World Health Organization and the UK Department for International Development. Recently he developed a training package for the Millennium Development Goals, one of the key strategies adopted by the United Nations to reduce world poverty.

The George Institute for International Health seeks to gather evidence to address the growing problems of heart and vascular disease, injury, mental illness and neurological diseases through high-quality research, evidence-based policy development and a range of capacity development programs. Epidemiology and biostatistics are central to most aspects of The George Institute's research and development activities. Methodological expertise in these areas is concentrated within the Epidemiology and Biostatistics Division at The George Institute. Staff in this Division contribute to study design and undertake data analysis for each of the Institute programs. In addition, the Division has its own research and development projects.

Emma Eyles
Research Australia
thegeorgeinstitute