摘要：Estimates of deaths attributable to obesity in the United States rely on estimates from epidemiological cohorts of the relative risk of mortality associated with obesity. However, these relative risk estimates are not necessarily appropriate for the total US population, in part because of exclusions to control for baseline health status and exclusion or underrepresentation of older adults. Most deaths occur among older adults; estimates of deaths attributable to obesity can vary widely depending on the assumptions about the relative risks of mortality associated with obesity among the elderly. Thus, it may be difficult to estimate deaths attributable to obesity with adequate accuracy and precision. We urge efforts to improve the data and methods for estimating this statistic. The increasing prevalence of obesity over the last 2 decades has generated considerable concerns about its health burdens. It is frequently stated in scientific and lay literature that obesity causes about 300 000 deaths per year in the United States. 1– 5 It has been suggested that obesity is second only to smoking as a preventable cause of death. 1, 3 Many methodological and conceptual difficulties arise in attempting to estimate the number of deaths in the United States that are attributable to obesity. The concept of a death being “attributable” to obesity generally relies on a statistical excess of deaths among people who are obese, relative to people who are nonobese, rather than on identifying obesity as the specific cause of death for an individual. Obesity itself may not be the only contributing factor to this statistical excess, but rather a marker for other factors such as sedentary behavior or adverse body fat distribution. Existing estimates of deaths attributable to obesity 5 are based on body mass index (BMI; defined as weight in kilograms divided by height in meters squared). BMI is correlated with body fat and is the measure recommended by a National Heart, Lung, and Blood Institute expert committee for use in clinical practice and epidemiological studies. 6 In this article, we restrict our discussion to the context in which obesity is defined by BMI and relative risk estimates from epidemiological cohorts are used to generate estimates of the number of deaths owing to obesity. We discuss some of the issues involved in finding appropriate relative risks to apply to the US population. Attempts to control for confounding by baseline health status affect estimates of the relative risk associated with obesity and thus estimates of deaths attibutable to obesity. Estimates of deaths owing to obesity are particularly sensitive to the precision and accuracy of estimates of relative risk in the elderly.
