Hip and waist circumference ‘should be included in CVD risk prediction models’

1 February 2012

MedWire News: The effect of central obesity on mortality risk may be significantly underestimated without adjustment for hip circumference, suggest study results.

The team, led by Adrian Cameron (Deakin University, Victoria, Australia), found that adding waist and hip circumference to a Framingham-type model for cardiovascular disease (CVD) or all-cause mortality resulted in a marked increase in the model’s predictive capacity.

“Hip and waist circumference should be considered jointly for inclusion in CVD risk prediction models and in the assessment of obesity-related risk of future death,” remark Cameron et al.

Writing in the International Journal of Epidemiology, they explain that a higher waist circumference and lower hip circumference are both associated with increased CVD risk, despite being directly correlated.

“The real effects of visceral obesity may therefore be underestimated when hip circumference is not fully taken into account.”

Using data from a population-based cohort of almost 8000 individuals, Cameron and co-authors therefore investigated the effect of adding waist and hip circumference to a risk prediction model based on the Framingham Heart Study (including age, gender, total cholesterol, high-density lipoprotein cholesterol, systolic blood pressure, diabetes, blood pressure treatment, and cigarette smoking).

Before adjustment for hip circumference, no significant association was seen between waist circumference and CVD or all-cause mortality, reports the team. However, after additional adjustment for hip circumference, a strong and graded relationship with both all-cause and CVD mortality was observed.

Similarly, a strong negative relationship between hip circumference and both CVD and all-cause mortality was only observed after adjustment for waist circumference.

Furthermore, for those who died from cardiovascular causes, adding waist and hip circumference to the Framingham-type model increased the estimated 10-year cumulative CVD risk by more than 25.0% among 23.7% of the cohort whereas 4.5% had a decrease in estimated risk of more than 20.0%.

The authors conclude, therefore, that both waist and hip circumference should be included in CVD risk prediction models, and should be considered in future studies of obesity and mortality.

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Int J Epidemiol 2012; Advance online publication