Waist Circumference a Stronger Independent Predictor of Cardiovascular Disease Than BMI, According to International Study

April 10, 2006

"The IDEA study confirms to us the importance of measuring waist circumference, alongside current measures such as BMI, blood pressure, blood glucose, and lipid levels, in identifying patients in a primary care setting who are at increased cardiometabolic risk..."

INTERHEART [1,2] was the first large, international study to establish that obesity is a cardiovascular disease (CVD) risk factor that is statistically significant in basically all of the world's populations. Subsequent prespecified analyses of the INTERHEART results have further determined that a simple measure of waist-to-hip ratio is a more powerful predictor of obesity-associated CVD risk level than any other single measure of obesity (eg, body mass index [BMI]) or constellation of measures (eg, metabolic syndrome). [2]

Now, a second large trial, the International Day for the Evaluation of Abdominal Obesity (IDEA) study, has also shown that waist circumference is a stronger predictor of CVD outcomes than BMI. [3] First results of this large international study in over 170,000 people indicate that waist circumference is associated with CVD, independently of the relationship that BMI has with CVD risk, and regardless of age or geography.

The IDEA data were presented at the American College of Cardiology 55th Annual Scientific Session, held March 11-14, 2006 in Atlanta, Georgia, by Steve Haffner, MD, Professor of Medicine at the University of Texas Health Science Center (San Antonio), and member of the IDEA study Executive Committee. [3] "The IDEA study confirms to us the importance of measuring waist circumference, alongside current measures such as BMI, blood pressure, blood glucose, and lipid levels, in identifying patients in a primary care setting who are at increased cardiometabolic risk," said Dr. Haffner.

The IDEA study involved 6407 primary care physicians in 63 countries worldwide (the United States, for whatever reason, declined to participate). An unselected population made up of 177,345 patients aged 18 to 80 years who consulted their primary care physician for any reason on 2 prespecified half-days were enrolled in the study between May and July 2005. In addition to measurements of waist circumference, height, and body weight, demographic data were collected on gender, age, and highest level of education. The presence or absence of classic CVD risk factors (eg, hypertension, diabetes, dyslipidemia, and smoking status) and existing CVD (coronary heart disease, stroke, or prior revascularization) were also recorded.

The relevant characteristics of the IDEA population were:

  • Prevalence of overweight (BMI cutpoint 25-30 kg/m 2) did not differ regionally, but was consistently higher in men than in women

  • Prevalence of obesity (BMI ≥ 30 kg/m 2) was very high overall, highest in Canadian and Middle Eastern countries, and lowest in Asia

  • Waist circumference in both men and women was lowest in East Asia and highest in South Africa, the Middle East, and Eastern Europe.

The worldwide prevalence of physician-diagnosed CVD in men in the study was 16%, ranging from 10% in Latin America to 26% in Eastern Europe. In women, the worldwide prevalence was 12.5%, ranging from 7% in North America to 23% in Eastern Europe.

Analysis of the data showed that both waist circumference and BMI were independently associated with the presence of CVD. Each increase in waist circumference of 14 cm for men and 14.9 cm for women increased the likelihood of a person having CVD by between 21% and 40% (Table). When adjusted for BMI, waist circumference was an even stronger predictor of CVD, particularly in men.

Table. Age- and Region-Adjusted Odds Ratios (95% CI) for Risk of Cardiovascular Disease for a Change of 1 SD in Waist Circumference or BMI
  Men
(OR [95% CI])
Women
(OR [95% CI])
BMI without waist measurement 1.32
(1.29 - 1.35)
1.38
(1.35 - 1.41)
Waist circumference without BMI measurement 1.36
(1.33 - 1.39)
1.40
(1.36 - 1.40)
BMI adjusted for waist circumference 1.13
(1.09 - 1.17)
1.20
(1.16 - 1.24)
Waist circumference adjusted for BMI measurement 1.24
(1.19 - 1.25)
1.21
(1.17 - 1.25)
BMI = body mass index; CI = confidence interval; OR = odds ratio

The independent relationships with CVD for waist circumference and for BMI were seen in all geographical regions, even those where people were lean, such as East Asia. However, in 75% of regions, the association of CVD with waist circumference was stronger than the association with BMI.

The IDEA study is the first part of a large epidemiology program that includes 2 other international studies of intra-abdominal adiposity and its predictive relationship to cardiometabolic risk. The International Study of Prediction of Intra-Abdominal Adiposity and its Relationship with Cardiometabolic Risk/Intra Abdominal Adiposity (INSPIRE ME) will examine the relationship between cardiometabolic risk markers and previous CVD events and type 2 diabetes in 15,000 subjects. The INSPIRE ME Intra-Abdominal Adiposity (INSPIRE ME/IAA), a prospective trial, will investigate new-onset CVD and type 2 diabetes over a follow-up period of 3 years in 6000 subjects who will have measurement of intra-abdominal adiposity (by computed tomography), waist circumference, and cardiovascular risk factors such as C-reactive protein and insulin.

References
  1. Yusuf S, Hawken S, Ôunpuu S, on behalf of the INTERHEART Study Investigators. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet. 2004;364:937-952.

  2. Rosengren A, Hawken S, Ôunpuu S, et al, for the INTERHEART investigators. Association of psychosocial risk factors with risk of acute myocardial infarction in 11 119 cases and 13 648 controls from 52 countries (the INTERHEART study): case-control study. Lancet. 2004;364:953-962.

  3. Haffner SM, Despres J-P, Balkau B, et al. Waist circumference and body mass index are both independently associated with cardiovascular disease: The International Day for the Evaluation of Abdominal Obesity (IDEA) survey. J Am Coll Cardiol. 2006;47(4 suppl A):358A. Abstract 842-6.

The IDEA study was sponsored by an unrestricted grant from sanofi-aventis.

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