World Congress of Cardiology Report - Results from a large scale international study assessing prevalence of abdominal obesity in over 170,000 people have previously confirmed that a high waist circumference is associated with cardiovascular disease (CVD) independently of body mass index (BMI) and age.(1)
The International Day for the Evaluation of Abdominal Obesity (IDEA) study, which involved a random sample of more than 6,000 primary care practitioners in 63 countries, showed that abdominal obesity is highly prevalent worldwide among people in a primary care setting.
The results from this study confirm that although average waist circumference (WC) and BMI are lower in Asian populations, the impact of increased values remains the same in terms of prevalence of CVD. CVD is the leading cause of death and has emerged as a prominent public health issue around the world.(2) One in 8 men and one in 17 women die from CVD before the age of 65 in European countries.(3)
While death rates from CVD have been decreasing in Western countries, they have been increasing in many Asian countries, including Malaysia, China, Korea and Taiwan.(4) Although CVD risk is perceived to be low in economically developing countries, ischemic heart disease and stroke were 2 of the 3 leading causes of mortality in such countries in 1990. In absolute terms, India and China are the top two countries worldwide for deaths attributed to coronary heart disease (CHD) or stroke.(5)
In this context, the IDEA study provided an opportunity to assess the distribution of WC and BMI in primary care patients across three Asian regions compared with North-West Europe, taken as a reference Western population, in order to determine the regional association between WC, BMI and prevalent CVD and other cardiometabolic risk factors.
The three Asian regions studied were East Asia (China, Hong Kong, Korea, Taiwan), South Asia (India, Pakistan) and South East Asia (Indonesia, Malaysia, the Philippines, Singapore, Thailand, Vietnam). Eleven countries in Europe comprised the NW European population, namely Austria, Belgium, Denmark, Finland, France, Germany, Ireland, the Netherlands, Norway, Sweden, Switzerland. A total of 30,783 patients participated in the 12 Asian countries, while the 11 NW European countries included 29,582 patients. Approximately 50% of the participants were male.
"The IDEA study provides a unique platform for measuring waist circumference, alongside current measures such as BMI, blood pressure, blood glucose and lipid levels, in a large number of patients from varied geographic origins, in a primary care setting," said Professor Jean-Pierre Bassand, M.D., professor of cardiology at the University of Franche-Comte, in Besançon, France, and member of the IDEA Study Executive Committee. "This will help us to characterise cardiometabolic risk specifically among Asian populations (6), as compared to North Western Europe, and thus, we can more accurately identify patients at risk," continued Professor Bassand.
It is surprising how highly prevalent overweight, obesity and abdominal obesity are in the Asian platform. More than 40% of men and 35% of women are overweight (BMI 25 - 30 Kg/m2) or obese (BMI >30 Kg/m2). In South Asia (India and Pakistan), 56% of women are overweight or obese according these standard criteria.
When considering the different thresholds for WC, the prevalence of abdominal obesity according to NCEP/ATPIII WC criteria (>102/88cm) ranged from 6% (East and South East Asia) to 20% (South Asia) in men and from 22% (East and South East Asia) to 55% (South Asia) in women. When considering the IDF WC criteria (WC ≥90/80cm for Asia and ≥94/80cm for Europeans), the prevalence of abdominal obesity ranged from 38% (East and South East Asia) to 58% (South Asia) in men and from 51% (East and South East Asia) to 75% (South Asia) in women. This illustrates the differences among the Asian regions that cannot simply be due to ethnicity, but probably involve a range of genetic, socio-economic and cultural factors.
Interestingly in NW Europe, the prevalence of overweight (BMI 25 - 30 Kg/m2) was 42% in men and 29% in women, and the prevalence of obesity (BMI ≥30 Kg/m2) 22% in men and women, meaning that two thirds of the male and half of the female population in this study had excess body weight. The prevalence of abdominal obesity was 31% in men and 43% in women according to NCEP/ATPIII WC criteria and 58% in men and 67% in women according to IDF WC criteria (WC ≥94/80cm for Europeans).
When looking at the CVD prevalence in these different regions, the overall age-standardised prevalence of CVD in men was 15% in NW Europe (approximately 1 in 6 people), and slightly lower at 12–13% (about 1 in 7 to 8 people) across the three Asian regions. In women, the prevalence of CVD was lower in NW Europe (9%) than in the three Asian regions (12–13%).
When considering standard cutoffs for BMI or WC, it is therefore obvious that obesity and abdominal obesity are highly prevalent in Asia but are still lower than in Europe except may be for South Asia where they are similar to Europe. However, the prevalence of cardiovascular disease in this population of primary care patients was almost similar to, or even higher in Asian populations than in Europe. This analysis confirms that, despite lower WC and BMI, there is like a disproportionate rise in CHD across Asia. Adiposity as defined for Western population standards significantly underestimates the disease burdens from CVD. The impact of obesity (reflected by BMI and WC) may begin at different thresholds in Asian populations than among the Western population.
"IDEA is a study of unprecedented magnitude, and the wide range of ages and geographic origins included make the IDEA data a mine of invaluable information," commented Professor Bassand. "This data provide us with a unique opportunity to examine patient characteristics in various regions of the world, with a view to tailoring diagnostic and therapeutic approaches to suit local characteristics." Most recommended obesity thresholds assessing the risk of obesity-related diseases are based on studies conducted among Western (primarily Caucasian) populations , and no measures specific to the anthropometric characteristics of Asian populations are yet widely implemented.
Cardiometabolic risk is the global risk of developing type 2 diabetes and CVD. Cardiometabolic risk is determined by the presence of traditional risk factors such as LDL-cholesterol (bad cholesterol), hypertension (elevated blood pressure), type 2 diabetes and smoking as well as by a cluster of emerging markers linked to insulin resistance that are most frequently found in clinical practice among patients with abdominal obesity, especially those with an excess of intra-abdominal adiposity (too much "high risk" abdominal fat). Among these clustering emerging markers affecting cardiometabolic risk are increased C-reactive protein (CRP), a marker of inflammation, and reduced adiponectin, an adipose tissue protein that protects against the development of diabetes and CVD (7,8). These abnormalities are often found clustered together with abdominal obesity, elevated triglycerides (blood fat), low HDL-cholesterol levels (good cholesterol), elevated blood glucose (high blood sugar) and high blood pressure.(9)