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When information on other risk factors is available, how useful are measures of adiposity (obesity) for assessing cardio-vascular disease risk? If a clinician knows a patient's blood pressure, history of diabetes, and cholesterol levels, is any additional predictive value gained by assessing body mass index (BMI), waist circumference, or waist-to-hip ratio?
Expert opinion has been divided on these questions, and guidelines issued in the United States and other developed countries vary widely. Although some guidelines omit adiposity assessments, others recommend them as additional screening; still others formally include them in their prediction models.
Seeking to produce reliable estimates of associations between BMI, waist circumference, and waist-to-hip ratio with first-onset cardiovascular disease outcomes, the Emerging Risk Factors Collaboration, an international team of investigators funded by the British Heart Foundation and the United Kingdom's General Medical Council, recently analyzed 58 prospective studies comprising data on close to 220,000 participants in 17 countries. Participants had no history of cardiovascular disease when they were first examined, and at least a year's worth of follow-up data was available for each. Three fatal or first-ever nonfatal disease outcomes were examined: coronary heart disease, ischemic stroke, and coronary heart disease and any cerebrovascular disease.
The results show that when information on blood pressure, history of diabetes, and total and high-density lipoprotein cholesterol levels is available, additional data on BMI, waist circumference, and waist-to-hip ratio, assessed individually or in combination, don't significantly improve the prediction of first-onset cardiovascular disease.
The researchers emphasize that these results don't diminish the importance of weight control to prevent disease. The authors also note that although assessments of simple adiposity may be adequate in low-resource settings where no information on lipids is available, developing the capacity to assess lipids in such settings should be prioritized.—James M. Stubenrauch
The Emerging Risk Factors Collaboration. Lancet 2011;377(9771):1085-95.