Waist Circumference as a measurement of Cardio Vascular Risk

For may years we have recognized that obesity is a risk factor for cardiovascular disease, as well as being associated with insulin resistance and the development of Type 2 Diabetes.¹

However, all fat is not created equal. Intraabdominal fat or visceral fat, is more "metabolically active" and as such, is associated with the "Metabolic Syndrome". This syndrome is characterized by hypertension, hyperglycemia, low high density lipoprotein (HDL) cholesterol and the non-traditional risk factors of insulin resistance, hyperinsulinaemia, raised apolipoprotein B, and small dense low density lipoprotein (LDL) cholesterol particles.

Moreover, presence of these non-traditional markers (hyperinsulinaemia, raised apolipoprotein B, and small dense low density lipoprotein (LDL) cholesterol particles), predicts a 20 fold increase in risk of CV disease, even in the absence of hypertension, diabetes and elevated cholesterol.

Intraabdominal fat can be assessed using CT and MRI scanning, but most of us do not have ready access to these scans, especially for this purpose. However measurement of waist circumference and plasma triglyceride can give us an easy and accurate assessment of this risk factor. In fact, this measurement predicts subsequent coronary artery disease better than body mass index.⁴

Waist circumference is measured midway between the costal margin and the anterior superior iliac spine. Sensitivity and specificity analyses conducted in a sample of men aged between 30 and 65 years showed that a cut off point of a 90 cm waist measurement provides the best ability to distinguish men with hyperinsulinaemia and increased apolipoprotein B concentration from those with normal concentrations for both variables.² Furthermore, a fasting triglyceride concentration of 2 mmol/l provides the best cut off point to identify men with the small, dense, low density lipoprotein phenotype.²

By using these simple cut off values,it has been shown that more than 80% of men with a waist circumference 90 cm and fasting triglyceride concentrations 2 mmol/l are carriers of the atherogenic metabolic triad.³

It should be noted that there are sex and ethnic differences in the relation of waist measurement to accumulation of visceral adipose tissue, and there may be different cut off values for these groups.

Never the less, monitoring of waist circumference along with plasma triglyceride may provide the practitioner with another tool for the assessment of CV risk in white males. It may also be a marker that patients can more readily relate to, and can provide them with a "visible" improvement in their risk as their girth recedes.

- John Hickey

1. Chan JM, Rimm EB, Colditz GA, Stampfer MJ, Willett WC. Obesity, fat distribution, and weight gain as risk factors for clinical diabetes in men. Diabetes Care. 1994 Sep;17(9):961-9.(Level 3 Evidence)
    
2. Lemieux I, Pascot A, Couillard C, Lamarche B, Tchernof A, Almeras N, Bergeron J, Gaudet D, Tremblay G, Prud'homme D, Nadeau A, Despres JP. Hypertriglyceridemic waist: A marker of the atherogenic metabolic triad (hyperinsulinemia; hyperapolipoprotein B; small, dense LDL) in men? Circulation. 2000 Jul 11;102(2):179-84. (Level 3 Evidence)
    
3. Jean-Pierre Després, Isabelle Lemieux, and Denis Prud'homme. Treatment of obesity: need to focus on high risk abdominally obese patients.BMJ 2001 322: 716-720. (Review Article)
    
4. Ohlson LO, Larsson B, Svardsudd K, Welin L, Eriksson H, Wilhelmsen L, et al. The influence of body fat distribution on the incidence of diabetes mellitus. 13.5 years of follow-up of the participants in the study of men born in 1913. Diabetes 1985; 34:1055-1058 (Level 3 Evidence).

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