Data about the prevalence of abdominal obesity are not available in all countries, either in the population, or in a primary care setting. Even in cases where data about prevalence do exist, the subjects studied are often not representative of the background population, or the protocols for measuring waist circumference (WC) often differ. Thus, the comparability of studies in this setting is limited, and as a result, universal cut-off criteria for defining abdominal obesity cannot be identified.
The objective of this study was to estimate the prevalence of abdominal obesity in an unselected sample of patients consulting primary care physicians, to estimate the prevalence of cardiovascular risk factors (e.g. hypertension, diabetes, dyslipidemia), and to estimate the prevalence of abdominal obesity among these patients.
Waist circumference is a strong predictor of intra-abdominal adiposity, which is known to be a strong predictor of the different features of the Metabolic Syndrome associated with a higher risk of cardiovascular disease and diabetes, namely abnormal lipid profile, hypertension, abnormal glucose metabolism and inflammation.
The main IDEA study was carried out in 63 countries, and incorporated 177,345 patients from the five continents. The main results of the IDEA study were presented at the ACC meeting in March 2006, and showed that the median WC was variable according to the regions under study. Two regions in particular appeared to have a lower WC than the others, namely East Asia and South Asia. The main study also showed clearly that there is a gradual increase in the prevalence of cardiovascular disease across the quintiles of WC, for both men and women. The IDEA study also showed that WC, after adjustment for age and body mass index (BMI), was a strong predictor of the presence of cardiovascular disease in this population.
We report here on the so-called “lean” populations from Asia, and three regions were considered, namely East Asia (incorporating China, Hong Kong, Korea, Taiwan); South Asia (India and Pakistan) and South-East Asia (Indonesia, Malaysia, the Philippines, Singapore, Thailand and Vietnam). Altogether, these three regions represented about 30,000 patients and were compared to 30,000 patients from Western Europe.
There was a higher prevalence of low WC in both East Asia, and South-East Asia, as compared to South Asia. The profile in South Asia was intermediate, between East / South-East Asia, and Northwest Europe, in men. In women, however, there was a similar trend towards higher prevalence of low WC in East and South-East Asia, but the prevalence of high WC in India/Pakistan was particularly striking. The profile of the Indian and Pakistan female populations were very similar to the profile of the European populations.
When considering age-standardised prevalence of cardiovascular disease, and risk factors, it could be seen that the prevalence of hypertension and diabetes was particularly high in South Asia and South-East Asia, as compared to the other two regions, in both men and women. The most striking result is that WC is an independent predictor of the prevalence of diabetes in men, whereas BMI was not. In women, WC was an independent predictor of the presence of cardiovascular disease, and BMI was not. The same was true for diabetes, where once again, WC was a predictor, but BMI was not.
In summary, WC is a better predictor than BMI of the prevalence of diabetes in both men and women, and a better predictor of the prevalence of cardiovascular disease in women.
In conclusion, the prevalence of cardiovascular disease and its risk factors increases as waist circumference increases. The prevalence of obesity in South Asia is similar to that observed in Western Europe, and we noted a high prevalence of obesity in South Asia as compared to East and South-East Asia.
Waist circumference is closely associated with cardiovascular disease, and more so with diabetes, independently of BMI, in patients from primary care practice in Asia. There is a need to reconsider the thresholds for defining abdominal obesity in these so-called “lean” populations, as a unique threshold for all Asia populations would appear to be inappropriate.
*JP Bassand, JP Despres, B Balkau, S Haffner, J Deanfield, P Barter, KAA Fox, L Van Gaal, HU Wittchen, CE Tan, S Smith
Data about the prevalence of abdominal obesity are not available in all countries, either in the population, or in a primary care setting. Even in cases where data about prevalence do exist, the subjects studied are often not representative of the background population, or the protocols for measuring waist circumference (WC) often differ. Thus, the comparability of studies in this setting is limited, and as a result, universal cut-off criteria for defining abdominal obesity cannot be identified.
The objective of this study was to estimate the prevalence of abdominal obesity in an unselected sample of patients consulting primary care physicians, to estimate the prevalence of cardiovascular risk factors (e.g. hypertension, diabetes, dyslipidemia), and to estimate the prevalence of abdominal obesity among these patients.
Waist circumference is a strong predictor of intra-abdominal adiposity, which is known to be a strong predictor of the different features of the Metabolic Syndrome associated with a higher risk of cardiovascular disease and diabetes, namely abnormal lipid profile, hypertension, abnormal glucose metabolism and inflammation.
The main IDEA study was carried out in 63 countries, and incorporated 177,345 patients from the five continents. The main results of the IDEA study were presented at the ACC meeting in March 2006, and showed that the median WC was variable according to the regions under study. Two regions in particular appeared to have a lower WC than the others, namely East Asia and South Asia. The main study also showed clearly that there is a gradual increase in the prevalence of cardiovascular disease across the quintiles of WC, for both men and women. The IDEA study also showed that WC, after adjustment for age and body mass index (BMI), was a strong predictor of the presence of cardiovascular disease in this population.
We report here on the so-called “lean” populations from Asia, and three regions were considered, namely East Asia (incorporating China, Hong Kong, Korea, Taiwan); South Asia (India and Pakistan) and South-East Asia (Indonesia, Malaysia, the Philippines, Singapore, Thailand and Vietnam). Altogether, these three regions represented about 30,000 patients and were compared to 30,000 patients from Western Europe.
There was a higher prevalence of low WC in both East Asia, and South-East Asia, as compared to South Asia. The profile in South Asia was intermediate, between East / South-East Asia, and Northwest Europe, in men. In women, however, there was a similar trend towards higher prevalence of low WC in East and South-East Asia, but the prevalence of high WC in India/Pakistan was particularly striking. The profile of the Indian and Pakistan female populations were very similar to the profile of the European populations.
When considering age-standardised prevalence of cardiovascular disease, and risk factors, it could be seen that the prevalence of hypertension and diabetes was particularly high in South Asia and South-East Asia, as compared to the other two regions, in both men and women. The most striking result is that WC is an independent predictor of the prevalence of diabetes in men, whereas BMI was not. In women, WC was an independent predictor of the presence of cardiovascular disease, and BMI was not. The same was true for diabetes, where once again, WC was a predictor, but BMI was not.
In summary, WC is a better predictor than BMI of the prevalence of diabetes in both men and women, and a better predictor of the prevalence of cardiovascular disease in women.
In conclusion, the prevalence of cardiovascular disease and its risk factors increases as waist circumference increases. The prevalence of obesity in South Asia is similar to that observed in Western Europe, and we noted a high prevalence of obesity in South Asia as compared to East and South-East Asia.
Waist circumference is closely associated with cardiovascular disease, and more so with diabetes, independently of BMI, in patients from primary care practice in Asia. There is a need to reconsider the thresholds for defining abdominal obesity in these so-called “lean” populations, as a unique threshold for all Asia populations would appear to be inappropriate.
*JP Bassand, JP Despres, B Balkau, S Haffner, J Deanfield, P Barter, KAA Fox, L Van Gaal, HU Wittchen, CE Tan, S Smith
Session Number : 710001
Session Title: Clinical Trial Update I
Conclusion
DISCUSSANT: Tuomilehto, J., Helsinki, Finland
Cardiovascular disease prevalence and relationship with waist circumference (WC) in Asian versus European primary health care patients: the International Day for the Evaluation of Abdominal Obesity (IDEA) study - Discussant
Obesity is the major risk factor for type 2 diabetes and cardiovascular disease. There are several fatness measures that have been proposed for the assessment of disease risk. It has been speculated that they may operate differently in different populations, age groups and sexes. The issue of the relative importance of different anthropometric determinants of diabetes and other chronic diseases is still unclear. Thus far, no proper comparative analysis on this matter has been carried out.
In general, it is a great challenge to carry out multinational studies and especially, to interpret results obtained. Many genetic, cultural, environmental, etc. factors that mostly remain unmeasured can result in biases that lead to incorrect conclusions. The same applies to the “population stratification” since even within one country marked differences in the exposure, outcome and confounding factors may exist, and these are difficult to control in geographic data analyses.
In order to control any risk factor, including obesity, in the health care setting, the basic and necessary issue is to measure and document the risk factor value, and to inform people about their current situation and, if possible, provide an interpretation about the trends observed. The International Day for the Evaluation of Abdominal Obesity (IDEA) project aims at producing international comparative data among many populations worldwide. The data were collected in customers of primary health care.
Thus, the study was not population-based strictly speaking, but had no other selection criteria and, therefore, can be considered more or less representative of the adult background population. The obesity indicators, BMI and WC, were also correlated with known cardiovascular disease and diabetes. Due to the nature of the survey, the correlations were cross-sectional. Thus, it is not possible to draw inferences about causality.
There are other data sets from multinational studies based on epidemiological, population-based samples, i.e. the WHO MONICA Project (MONItoring trends and determinants in CArdiovascular disease) that has reported 10-year trends in obesity in many populations (1). The CODA Project (unpublished) has been set up to provide an answer to these questions, primarily regarding diabetes as outcome. Using individual participant data meta-analysis of population-based survey data, we analysed the association of BMI and WC with diabetes risk (presumably almost all type 2) in 29 data sets from 15 countries comprising 204,000 persons over age 30.
Both cross-sectional and prospective analyses were carried out. A total of 106,000 persons with baseline glucose measurements and 1.34 million person years of follow-up for diabetes were included in the analysis. Age-adjusted, sex-specific risk ratios for diabetes were predicted from body fatness using odds ratios from logistic regression in cross-sectional analyses and hazard ratios from Cox proportional hazards regression in prospective analyses. These study-level risk ratios were combined using random effects models.
Diabetes at baseline was defined as newly diagnosed diabetes at the baseline survey using 2003 American Diabetes Association (based on fasting glucose) and 1999 WHO criteria (based on 2-hour glucose after a glucose tolerance test), and diabetes incidence during the follow-up (diabetes based on glucose measurement at a repeat examination, self-reported diabetes, or diabetes medication) depending on study.
Correlation between BMI and WC was 0.83 for men and 0.82 for women, ranging from 0.59 to 0.92 across studies. Pooled risk ratios (odds or hazard ratios) varied from 1.70 to 2.13 per one standard deviation of either fatness measure; they were stronger for WC than for BMI in separate models, and similar in men and women. In analyses of categories of BMI or WC, the risk curve was exponential, increasing even at low body fatness. Between-study heterogeneity existed, but was quantitative, not qualitative. The heterogeneity of risk ratios was not explained by study-specific covariates of mean age, geographic area, baseline study year, or mean follow-up time (in cohorts), but was inversely related to the population prevalence or incidence of diabetes.
The results from the CODA Project demonstrated that the association of BMI and WC with diabetes is strong and is largely similar in both sexes, the measure of body fatness, and diabetes outcome. Although risk became stronger as body fatness increased, there was no clear fatness threshold either for BMI or WC to define “a high relative risk” for diabetes. Information on both parameters should be used in the estimation of the risk of type 2 diabetes in clinical practice. Thus, obesity should be measured not only using body weight but using also waist circumference which is a good surrogate for visceral adiposity. The CODA study showed that high BMI and high WC both predict type 2 diabetes independently.
Conclusion
BMI and waist circumference both predict the risk of CVD and type 2 diabetes in all populations. Several collaborative data sets exist that provide a good basis for the assessment of these associations, not only cross-sectionally but also prospectively.
1. References:
Silventoinen K, Sans S, Tolonen H, et al: Trends in obesity and energy supply in the WHO MONICA Project. Int J Obes Relat Metab Disord 2004;28:710-8. CODA study Steering committee: S Duval (principal investigator) Minneapolis, USA, DR Jacobs Jr. (co-investigator), Minneapolis, USA, K Silventoinen (co-investigator/project manager), Minneapolis, USA and Helsinki, Finland, J Tuomilehto (co-investigator), Helsinki, Finland, M Stern (co-investigator), San Antonio, USA, R Valdez (co-investigator/CDC project officer), Atlanta, USA