International Differences in Mortality at Older Ages Dimensions and Sources (2010) / Chapter Skim
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6 Can Obesity Account for Cross-National Differences in Life-Expectancy Trends?--Dawn E. Alley, Jennifer Lloyd, and Michelle Shardell
6 Can Obesity Account for Cross-National Differences in Life-Expectancy Trends?--Dawn E. Alley, Jennifer Lloyd, and Michelle Shardell
Pages 164-192
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From page 164... ...
Several trends suggest that the effect of obesity on life expectancy will increase in the future, including (1) an increase in abdominal adiposity, reflected by higher waist circumference at a given body mass index (BMI)
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From page 165... ...
Only men in Italy and Japan have an obesity prevalence below 10 percent. Overall patterns are similar among adult women.
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From page 166... ...
Canada 30 Denmark 25 England France 20 Italy 15 Japan 10 Netherlands Spain 5 USA 0 1978 1981 1984 1987 1990 1993 1996 1999 2002 Year FIGURE 6-1 Trends in adult obesity prevalence by country and sex, 1978-2004. SOURCES: Data are nationally representative unless otherwise noted.
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From page 167... ...
The first and last estimates of adult obesity prevalence available for each country between 1978 and 2004 were used to estimate annual change in obesity prevalence. Among the 10 countries included here, the United States ranked eighth in life expectancy at age 50 for men (28.9 years)
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From page 168... ...
Australia, ages 55 -64 30 Canada, ages 45 -69 25 England, ages 55 -64 France, ages 50 -59 20 Italy, ages 55 -64 15 Japan, ages 50 -59 10 Netherlands, ages 55 -64 5 USA, ages 50 -59 0 1978 1981 1984 1987 1990 1993 1996 1999 20 02 20 04 Year FIGURE 6-2 Trends in obesity prevalence by country and sex: Older adults, 1978 2004. SOURCES: Data are nationally representative unless otherwise noted.
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From page 169... ...
Among women, there was some evidence of a negative association between change in adult obesity prevalence and changes in life expectancy at age 50 (r = –0.421)
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From page 170... ...
, 1978 -2004 FIGURE 6-3 Trends in life expectancy at age 50 and adult obesity prevalence by country and sex. SOURCE: Figure 6-1 and Glei, Meslé, and Vallin, Chapter 2, in this volume.
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From page 171... ...
If obesity is slowing life expectancy gains in the United States, it is likely that it is also affecting life expectancy trends in other countries, particularly countries like Australia, Canada, and England, which have also experienced rapid increases in obesity prevalence. Among men, there was little evidence of an association between changes in adult obesity prevalence and changes in life expectancy at age 50, although we did find some evidence of an association among women.
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From page 172... ...
. In one large cohort study of adults ages 50-71 at baseline, the excess mortality risk associated with obesity (relative to a BMI of 23.5-24.9)
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From page 173... ...
; CHD = coronary heart disease; normal weight = body mass index (BMI) 18.5-24.9kg/m2; overweight = BMI 25.0-29.9kg/m2; obese = BMI ≥ 30kg/m2.
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From page 174... ...
The following section explores the potential effects of BMI on trends in life expectancy. OBESITY AND LIFE EXPECTANCY In order to move from a discussion of mortality risks at an individual level to a discussion of life expectancy at the population level, we must examine the size of the population at increased risk for poor outcomes.
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From page 175... ...
Class II obesity: BMI = 35.0-39.9kg/m2; Class III obesity: BMI ≥ 40.0kg/m2. Fig6-5.eps landscape
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From page 176... ...
White Men White Women 8 8 Age Age 7 7 6 6 50 50 5 5 60 60 4 4 70 70 3 3 2 2 1 1 0 0 Years of Life Lost Years of Life Lost –1 –1 –2 –2 –3 –3 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 BMI BMI Black Men Black Women 8 8 Age Age 7 7 6 6 50 50 5 5 60 60 4 4 70 70 3 3 2 2 1 1 0 0 Years of Life Lost Years of Life Lost –1 –1 –2 –2 –3 –3 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 BMI BMI FIGURE 6-6 Years of life lost relative to life expectancy for a BMI of 24, by age, race, and sex. SOURCE: Fontaine et al.
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From page 177... ...
In order to estimate the effect of increasing obesity prevalence on trends in life expectancy at age 50 in the United States, we applied Fontaine and colleagues' estimates (Fontaine et al., 2003) of YLL at age 50 to the BMI distribution from NHANES II (1976-1980)
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From page 178... ...
For example, if all sex- and BMI-specific YLLs were uniformly twice as high as those estimated by Fontaine and colleagues, the projected reduction in life expectancy would be twice as high. These data suggest that increasing obesity prevalence is likely to slow life-expectancy growth in the United States.
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From page 179... ...
Although obesity is associated with increased incidence of chronic diseases, including diabetes and cardiovascular disease, many of these chronic conditions are also associated with both involuntary weight loss and increased mortality. Thus, BMI appears to have an attenuated or negative association with mortality among those with existing illness.
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From page 180... ...
However, simple measures of anthropometry can provide useful indicators of body composition and fat distribution. In particular, waist circumference, an indicator of abdominal adiposity, may provide a useful indicator of mortality risk (Baik et al., 2000; Koster et al., 2008; Visscher et al., 2001)
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From page 181... ...
CAN OBESITY ACCOUNT FOR CROSS-NATIONAL DIFFERENCES Males 3.0 Age 50 Current 2.5 Relative Risk 2.0 1.5 1.0 0.5 ≥40 <18.5 18.5- 21.0 - 23.5 - 25.0 - 26.5 - 28.0 - 30.0 - 35.0 20.9 23.4 24.9 26.4 27.9 29.9 34.9 39.9 BMI Group Females 3.5 Age 50 Current 3.0 2.5 Relative Risk 2.0 1.5 1.0 0.5 ≥40 <18.5 18.5- 21.0 - 23.5 - 25.0 - 26.5 - 28.0 - 30.0 - 35.0 20.9 23.4 24.9 26.4 27.9 29.9 34.9 39.9 BMI Group FIGURE 6-7 Association between BMI and mortality by sex, based on current BMI (ages 50-71)
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From page 182... ...
98 Australia 94 Canada 90 Denmark England 86 France 82 Netherlands USA 78 74 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 20 01 20 03 Year FIGURE 6-8 Trends in mean waist circumference by country and sex, 1981 Fig6-8.eps 2003. SOURCES: Data are nationally representative unless otherwise noted.
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From page 183... ...
American women had smaller waist circumference than British women after adjusting for hip or thigh girth, possibly related to greater total body size. These results suggest that it is important to consider body composition in cross-national comparisons in the health consequences of obesity.
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From page 184... ...
INTERNATIONAL DIFFERENCES IN MORTALITY AT OLDER AGES rates of obesity at younger ages have two important implications for mortality. First, because the association between obesity and mortality is higher at younger ages, a rising prevalence of obesity at these ages is likely to have a greater effect on population life expectancy.
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From page 185... ...
Thus, increases in obesity prevalence have important effects on the population burden of morbidity. As BMI increases, disability risk increases more than mortality risk (Al Snih et al., 2007; Lang et al., 2008)
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From page 186... ...
. Meta-analysis of the effect of excluding early deaths on the estimated relationship be tween body mass index and mortality.
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From page 187... ...
. The obesity paradox: Body mass index and outcomes in patients with heart failure.
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From page 188... ...
. Elevated body mass index and mortality risk in the elderly.
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From page 189... ...
. Body mass index and mortality: A meta-analysis based on person-level data from twenty-six observational studies.
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From page 190... ...
and seasonal variation in body mass index and waist circumference in the Netherlands. International Journal of Obesity and Related Metabolic Disorders, , 1309-1316.
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From page 191... ...
International Journal of Obesity, , 152-159. Wolf, A., and Colditz, G
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From page 192... ...
= expected years of life lost given BMI = b, from Fontaine et al.
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