Body Mass Index: From Quételet to Evidence ... - Giorgio Bedogni

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6 Giorgio Bedogni, Claudio Tiribelli and Stefano Bellentani curvilinear association between BMI and mortality was in fact detected in: 1) current or former smokers with a history of disease; 2) current or former smokers without a history of disease; 3) subjects who had never smoked and with a history of disease; and 4) subjects who had never smoked and without a history of disease. In line with the expectations, smoking and a history of disease increased the risk of mortality among the very lean and the very heavy. In healthy people who had never smoked, the nadir of the curve for BMI and mortality was found at a value of BMI of 23.5 to 24.9 kg / m 2 in men and 22.0 to 23.4 kg / m 2 in women. White males and females with BMI of 40.0 kg / m 2 and over had a relative risk of death of 2.58 and 2.00, respectively, as compared with those with a BMI between 23.5 and 24.9 kg / m 2 (Figure 3). Black men and women with the highest BMI had however lower risks of death (1.35 and 1.21). A high BMI was most predictive of death from cardiovascular disease, especially in men. Collectively, the risk of death from all causes increased throughout the range of moderate and severe overweight for both men and women in all age groups. Figure 3. Relationship between the risk of death and BMI in US white mean and women. The graph was drawn from the data of Calle et al. [55].
Body Mass Index: From Quételet to Evidence-Based Medicine 7 A recent study, performed on about 900000 US individuals followed for 16 years, offers important new information on the relationship between BMI and the risk of death from cancer [56]. In men with BMI ≥ 40 kg/m 2 , the relative risk of death from cancer was 1.52 as compared to men with BMI between 18.5 and 24.9 kg/m 2 ; in women with BMI ≥ 40 kg/m 2 , the relative risk of death from cancer was 1.62 as compared to women with BMI between 18.5 and 24.9 kg/m 2 . In both genders, BMI was significantly associated with higher rates of death due to cancer of the esophagus, colon and rectum, liver, gallbladder, pancreas, and kidney; the same was observed also for death due to non-Hodgkin’s lymphoma and multiple myeloma. Significant trends of increasing risk with higher BMI values were observed for death from cancers of the stomach and prostate in men and for death from cancers of the breast, uterus, cervix, and ovary in women. On the basis of these associations, it was estimated that the current patterns of overweight in the United States may account for 14 and 20 percent of all deaths from cancer in men and women respectively [56]. Body Mass Index at Work The classification of overweight proposed by the World Health Organization for adults is given in Table 1 [27]. This classification, based on the association between BMI and mortality (see previous paragraph), may not apply to non-caucasian populations [27]. This has been reemphasized more recently by an ad hoc committee of the World Health Organization asked to assess the need of different BMI cut-points for different ethnic backgrounds [26]. It should be noted that in this classification the term “overweight” applies to every value of BMI equal or greater than 25.0 kg/m 2 so that obesity (BMI equal or greater than 30 kg/m 2 ) is a “special case” of overweight [27]. In the classification of the US Expert Panel on the Identification, Evaluation and Treatment of Overweight in Adults [29], the term “overweight” is used instead to label a value of BMI comprised between 25.0 and 29.9 kg/m 2 . A classification of overweight for children should ideally be based on an association of BMI with disease such as that recognized for adults [57-59]. Because of the scarcity of data, however, BMI has been proposed as an index of adiposity in children mainly because of its association with adult BMI [15, 16, 60, 61]. The International Obesity Task Force (IOTF) has suggested to employ a value of BMI greater than the 95 th percentile for age to diagnose “overweight” and one comprised between the 85 th and 95 th percentile for age to diagnose a “risk of overweight” in children [15, 16, 62]. Cole et al. have developed international reference values of BMI to be used in children and adolescents [62]. They have averaged the centile curves of about 190000 children aged 2-18 years obtained from six cross-sectional studies (Brazil, Great Britain, Hong Kong, Netherlands, Singapore and United States) and developed age- and sex-specific cut-points that, at an age of 18 years, pass through the cutpoints of 25.0 and 30.0 kg/m 2 , the values used to define adult overweight and obesity (Table 2). Even if this definition is less arbitrary than others and offers the possibility of performing international comparisons, it should not be considered alternative to the use of local reference values (when available) because the two methods give often discordant results [63-65]. There is also some controversy as to whether BMI has the same prognostic value in adult and elderly subjects. The relative risk of death associated with adiposity seems in fact to decrease
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Body Mass Index: From Quételet to Evidence ... - Giorgio Bedogni

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