The importance of clinical measures of adiposity (such as body-mass index [BMI], waist circumference, and waist-to-hip ratio) in calculating cardiovascular risk remains controversial.  For example, both the World Health Organisation and the United States National Heart, Lung and Blood Institute recommend assessment of BMI, however several common cardiovascular disease risk scores (e.g. PROCAM) omit adiposity measures.  In this analysis, the Emerging Risk Factors Collaboration analysed records from 58 prospective studies to determine the separate and combined associations of BMI, waist circumference, and waist-to-hip ratio with the risk of first-onset cardiovascular disease.

Individual records were analysed from 221,934 people in 17 countries; serial adiposity measurements were made in 63,821 people.  Hazard ratios (HRs) were calculated per 1 standard deviation (SD) higher baseline values for three clinical adiposity measurements: BMI (1 SD = 4.56kg/m2), waist circumference (1 SD=12.6cm), and waist-to-hip ratio (1 SD=0.083).  Hazard ratios for cardiovascular disease were 1.23 for BMI, 1.27 for waist circumference, and 1.25 for waist-to-hip ratio.  Of note, adding information on BMI, waist circumferece, or waist-to-hip ratio to a cardiovascular disease risk prediction model using conventional risk factors did not significantly improve risk prediction, even when the three measures were considered in combination.

Conclusions:

In this analysis of 58 prospective studies, clinical measures of adiposity, such as BMI, waist circumference, and waist-to-hip ratio, did not improve cardiovascular disease risk prediction over the use of conventional risk factors such as blood pressure, diabetes and cholesterol.

• The Emerging Risk Factors Collaboration.  Separate and combined associations of body-mass index and abdominal adiposity with cardiovascular disease: collaborative analysis of 58 prospective studies.  Lancet 2011; 377:1085-1095.