riskstratificationofcoronaryheartdisease

Over the 20^th century, most countries in the world have experienced great transition in social structures, economics, politics, education, and home environment. This has resulted in a shift from agricultural and rural societies to industrial and urban societies in the first 3 quarters of the 20^th century, with a further shift in the last quarter to information-based societies. These social and economic transitions have resulted in major changes in population demography, industrial structure, income levels, expenditure patterns, education levels, family structures, eating habits, and physical activity (Yusuf et al., 2001). Along with these changes cardiovascular risk factors and disease rates have markedly increased. One in three deaths across the world is now due to heart disease and stroke, and this figure is rising rapidly. In absolute number this is 17 million deaths a year, six times more than due to HIV\AIDS related deaths, and this Cardiovascular (CVD) epidemic is not limited to industrialised countries (WHF, 2001). CVD is a major contributor to the global burden of disease among the non-communicable diseases. Coronary heart disease (CHD) is likely to be the most common cause of disability adjusted life years (DALYs) loss in 2020 as compared with its fifth position in 1990 (Murray & Lopez, 1996).

In the United Kingdom (UK) diseases of the heart and circulatory system are the main cause of death, accounting for over 235,000 deaths in 2000. More than one person in three (39%) die from CVD. The main forms of CVD are coronary heart disease and stroke. About half of deaths from CVD are from CHD and about a quarter are from stroke and the other quarter die from other CVDs such as heart failure, rheumatic heart disease, hypertensive disease, and other circulatory system disease (BHF, 2006). CHD itself is the most common cause of death in the UK. One in four men and one in six women die from the disease. CHD caused around 125,000 deaths in the UK in 2000, and was the most common cause of premature death in the UK with just under 45,000 premature deaths. Premature death is a death which occurs prior to that which is expected of the person in relation to developmental, physiological, psychological, and socio-cultural expectations or before the average age of death within a given population. Twenty four percent of premature deaths in men and 14% of premature deaths in women were from CHD (Petersen & Rayner, 2002).

South Asian migrants are at increased risk of cardiovascular disease. This susceptibility is well demonstrated in places as diverse as the UK, South Africa, the Caribbean, Singapore, the United States (US), and Canada. Even within India people moving from rural areas to large cities are at increased risk (McKeigue, 1994). Based on British research there is a virtual consensus that the proportionate excess risk of CHD in South Asians, as compared with the population of England and Wales, is greater than 40 per cent (McKeigue, 1989; 1994; Shaukat & de Bono, 1994; Enas et al., 1992). Moreover the 1999 Health Survey for England shows Pakistani and Bangladeshi men had prevalence rates of CVD about 60% to 70% higher than men in the general population, and the picture was similar for women (Erens & Primatesta, 1999; Erens et al., 2001). CVD is the primary cause of mortality among Asian Indians in the US. They appear to be at higher risk of heart disease compared with other ethnic groups (nearly three times the rate was seen in South Asian physicians living in the US compared with the Framingham offspring study) (Ivey et al., 2002) . South Asians, in Canada, had a greater prevalence of cardiovascular disease compared with Canadians of European or Chinese descent; 11%, 5%, and 2%, respectively, P = 0.0004 (Anand et al., 2000).

The latest estimate of the ethnic minority population in Great Britain from the 2001 census shows that approximately half was made up of the three groups originating from the Indian subcontinent - the Indian, Pakistani, and Bangladeshi populations. These represent 1,916,000 South Asians of a total 4,039,000 minority population (Haskey & Scott, 2001).

Because cardiovascular disease has become the number one killer worldwide since the end of the 20^th century, widespread deployment of affordable preventive strategies is essential for both developed and developing countries. However this is not possible without exact knowledge of the nature of the disease, its risk factors, and how it may be prevented in the different susceptible populations (Murray & Lopez, 1996). Diabetes and insulin resistance, characterised by glucose intolerance, raised plasma insulin, increased triglycerides, decreased high density lipoprotein (HDL) cholesterol, and central obesity, are more prevalent in UK South Asians than European whites. These are proposed as the underlying factors in high rates of coronary heart disease among South Asians worldwide and have been related to lack of exercise and obesity (Shaukat & de Bono, 1994).