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Epidemiology and Health Economics of Obesity
OBESITY
Epidemiology and Health Economics of Obesity
WHO classification of overweight Classification
BMI (kg/m2)
• Underweight
< 18.5
• Normal • Overweight Pre-obese Obese class I Obese class II Obese class III
18.5–24.9 ≥ 25.0 25.0–29.9 30.0–34.9 35.0–39.9 ≥ 40
Jacob C Seidell
Definition of obesity The most recent WHO classification of body weight is shown in Figure 1. In many community studies in affluent societies, this scheme has been simplified and body mass index (BMI) cut-off points of 25 kg/m2 and 30 kg/m2 are used to define ‘overweight’ and ‘obesity’. The prevalence of both very low BMI (< 18.5 kg/m2) and very high BMI (≥ 40 kg/m2) is usually about 1–2% or less in the general population, but these individuals are seen more commonly by health services. Over the last decade, much research has suggested that, to classify overweight individuals accurately with respect to health risks, both BMI and an indicator of fat distribution must be considered. Traditionally, this indicator has been waist: hip circumference ratio. However, it is increasingly clear that this complex classification of BMI and waist:hip ratio is not a powerful tool in health promotion and may be replaced by a classification based on waist circumference alone (see page 14).
Increased Moderately increased Severely increased Very severely increased
1
of low socioeconomic status. The prevalence increases with age until about 70 years, then declines. Obesity is also common in other parts of the world. Relatively high prevalences are found in the former socialist economies of Eastern Europe and Latin America, and in the Caribbean, the Middle East and North African countries. Recent trend data suggest that the very high prevalence of obesity seen in some former socialist economies of Europe (as high as 45% in women in parts of Russia and Lithuania) may be declining, but other reports show that obesity is still increasing in Latin America, the Caribbean and the Middle East. Obesity is uncommon in sub-Saharan Africa, China and India, though the prevalence seems to be increasing, particularly in affluent populations in larger cities. In these countries, both undernutrition and overnutrition are increasing; this is related to growing inequalities in income and access to food.
Prevalence Estimates of the prevalence of obesity are uncertain because of lack of data, differences between countries within the same region, and secular trends. Taking the mid-point of the estimates (Figure 2) gives a figure of about 250 million obese adults worldwide (about 7% of the total adult population). The true prevalence of obesity is likely to be about 5–10%. In most countries, the prevalence of overweight (BMI 25–30 kg/m2) is about two to three times as great as the prevalence of obesity; thus, as many as 1 billion individuals may be overweight or obese. It has been demonstrated in many reviews that obesity (BMI ≥ 30 kg/m2) is common in most countries with established market economies and is increasing (Figures 3 and 4), but the prevalence and rate of increase varies between and within these countries; for example, in France, the prevalence is 10% in Toulouse and 22% in Strasbourg. Obesity is usually more common in those
Costs of obesity Overweight and obesity are likely to be major contributors to total health care costs in affluent societies, but there is an urgent need for better data on all sources of costs associated with obesity. Such data are vital for efforts to convince governments and health professionals about the importance of the problem of overweight and obesity in social and economic terms, and they may help improve the cost-effectiveness of strategies for the management and prevention of obesity. Direct costs (Figure 5) Direct costs comprise costs to the community from diversion of resources to the treatment of obesity, and the cost of diagnosis and treatment of diseases associated with obesity. Direct costs vary between countries because of differences in: • the prevalence of obesity • the definition of obesity and the reference population (different BMI cut-off points used) • relative risks of obesity-related illnesses • costs of diagnosis and treatment of obesity-related illnesses • methods used to calculate the costs. Two methods have been used to calculate the direct costs of obesity:
Jacob C Seidell is Head of the Department of Chronic Diseases Epidemiology at the National Institute of Public Health, Bilthoven, Netherlands, and Honorary Professor in the Department of Nutrition at the University of Glasgow, UK. He trained in nutrition and epidemiology in Wageningen, Netherlands. His main research interest is obesity.
MEDICINE
Associated health risks Low (but risk of other clinical problems increased) Average
5
© 2003 The Medicine Publishing Company Ltd
OBESITY
Estimated world prevalence of obesity
• • • • • • • •
Established market economies Former socialist economies India China Other Asian countries Sub-Saharan Africa Latin America and Caribbean Middle East
Population aged ≥ 15 years (millions) 640 330 535 825 430 276 280 300
Prevalence of obesity (%) 15–20 20–25 0.5–1.0 0.5–1.0 1–3 0.5–1.0 5–10 5–10
Approximate estimate (with mid-point) of number of obese individuals (millions) 96–128 (112) 66–83 (75) 3–7 (5) 4–8 (6) 4–12 (8) 1–3 (2) 14–28 (21) 15–30 (22)
3616
World
(251)
Source: Murray C J L, Lopez A D. The Global Burden of Disease. Cambridge: Harvard University Press, 1996.
2
• the fraction of incidence of diseases attributable to obesity multiplied by the costs of these diseases – total direct costs are the sum of these costs • the fraction of use of medical care attributable to obesity (e.g. excess consultations with general practitioners and medical specialists, excess hospitalization, excess medication) – total direct costs are the sum of these costs. Despite these differences, most estimates are about 2–8% of total health-care costs. It has also been shown that the direct costs associated with overweight (BMI 25–30 kg/m2) are about double the direct costs associated with obesity (BMI > 30 kg/m2). However, these calculations are crude and involve assumptions
that may lead to an overestimation of the costs of obesity (e.g. neglect of adjustment for social class), or underestimation (e.g. many diseases are excluded from the calculation, the definition of obesity is usually narrow). Indirect costs Indirect costs of obesity are related to loss of productivity through absenteeism, provision of disability pensions and premature death. There is a lack of good economic analysis in this field, though research from Sweden, Finland and the Netherlands shows that obesity is associated with increased sick leave and need for disability pensions (Figure 6). In obese
Prevalence of obesity in women
25
25
20
20
Obese women (%)
Obese men (%)
Prevalence of obesity in men
15
10
5
15
10
5
0
19 78 19 79 19 80 19 81 19 82 19 83 19 84 19 85 19 86 19 87 19 88 19 89 19 90 19 91 19 92 19 93 19 94 19 95 19 96
19 78 19 79 19 80 19 81 19 82 19 83 19 84 19 85 19 86 19 87 19 88 19 89 19 90 19 91 19 92 19 93 19 94 19 95 19 96
0
Year USA Germany
Year UK Netherlands
USA Germany 4
3
MEDICINE
UK Netherlands
6
© 2003 The Medicine Publishing Company Ltd
OBESITY
Direct costs of obesity
• • • • •
USA USA Australia Netherlands France
1986 1988 1990 1989 1992
Definition of obesity 2
BMI > 29 kg/m BMI > 29 kg/m2 BMI > 30 kg/m2 BMI > 25 kg/m2 BMI > 27 kg/m2
Percentage of health care costs 5.5 7.8 2 4 2
2.2
Men Women
2.0
Relative risk compared to BMI < 22.5 kg/m2
Year
Provision of disability pensions and BMI in Finnish adults
Most costs are additonal to those incurred at BMI 22–23 kg/m2
1.8
1.6
1.4
1.2
5 1.0
Finns, chronic cardiovascular disease and musculoskeletal disorders increase the likelihood of receiving a disability pension. The likelihood of receiving a disability pension for respiratory diseases is increased in very lean individuals, but this probably reflects the underlying relationship between heavy smoking and leanness. In a group of Dutch civil servants, obese men and women (BMI > 30 kg/m2) were more likely to be absent from work for all medical reasons combined, as well as for more specific problems (psychological and musculoskeletal disorders).
2. 5 >3
2. 4 .0 –3 30
27 .5 –
29
.9
.4 25
.0 –
27
.9 24
BMI (kg/m2) Source: Rissanen A et al. BMJ 1990; 301: 835–7.
6
• costs of adaptations to a larger body size (e.g. tailormade clothing for larger sizes, adaptations to furniture) • costs of weight management/control (in the USA, $30 billion per year is spent on weight-loss remedies). The costs of obesity for an obese individual may be only partly reflected in economic costs, however; there are also consequences in terms of diminished social functioning and quality of life. Knowledge about the relationship between obesity and diminished social, mental and physical functioning and economic situation is limited.
Personal costs Some direct and indirect costs may be paid partly by society and partly by individuals; the proportions vary between countries and between individuals. Increasingly, in European countries, a minimum cost related to treatment of illness is paid by patients. Insurance policies covering health-care costs vary in their reimbursement strategies. Obese individuals may earn less than their lean counterparts even when earnings are corrected for intellectual ability and social background. One prospective study showed that overweight young women (aged 16–24 years at baseline) had completed fewer years of school, were less likely to be married, had lower household incomes and experienced higher rates of household poverty than women who were not overweight after 7 years of follow-up. These results were independent of baseline socioeconomic status and aptitude test scores. Prospective studies in Denmark and the USA confirmed that obesity in young adults determines lower social class attainment and income. The relationship between social class and obesity is complex, and it has been proposed that there may be common underlying genetic causes that may promote obesity and tend to reduce social class. However, discrimination against obese young adults has been well documented and remains the most likely explanation for these observations. Other excess costs for obese individuals may include: • additional costs of health and life insurance • costs of adaptation to impaired physical functioning – the strong relationship between obesity and difficulty performing activities of daily life (e.g. carrying groceries, climbing stairs, bending and kneeling, walking, bathing, dressing) means that obese individuals may need paid or unpaid assistance
MEDICINE
22 .5 –
<2
2. 5
0.8
FURTHER READING Bulpitt C J, Battersby C, Palmer A J et al. Association of Symptoms of Type 2 Diabetic Patients with Severity of Disease, Obesity and Blood Pressure. Diabetes Care 1998; 21: 111–15. Gortmaker S L, Must A, Perrin J M et al. Social and Economic Consequences of Overweight in Adolescence and Young Adulthood. N Engl J Med 1993; 329: 1008–12. Lean M E J, Han T S, Seidell J C. Impairment of Health and Quality of Life in Men and Women with a Large Waist. Lancet 1998; 351: 853–6. Seidell J C. Time Trends in Obesity: An Epidemiological Perspective. Horm Metab Res 1997; 29: 155–8. Seidell J C, Flegal K M. Assessing Obesity: Classification and Epidemiology. Br Med Bull 1997; 53: 238–52. Sjöström L, Narbro K, Sjöström D. Costs and Benefits when Treating Obesity. Int J Obes 1995; 19: (Suppl. 6): S9–12. WHO. Obesity: Preventing and Managing the Global Epidemic. Geneva: WHO, 1998.
7
© 2003 The Medicine Publishing Company Ltd
Epidemiology and Health Economics of Obesity
WHO classification of overweight Classification
BMI (kg/m2)
• Underweight
< 18.5
• Normal • Overweight Pre-obese Obese class I Obese class II Obese class III
18.5–24.9 ≥ 25.0 25.0–29.9 30.0–34.9 35.0–39.9 ≥ 40
Jacob C Seidell
Definition of obesity The most recent WHO classification of body weight is shown in Figure 1. In many community studies in affluent societies, this scheme has been simplified and body mass index (BMI) cut-off points of 25 kg/m2 and 30 kg/m2 are used to define ‘overweight’ and ‘obesity’. The prevalence of both very low BMI (< 18.5 kg/m2) and very high BMI (≥ 40 kg/m2) is usually about 1–2% or less in the general population, but these individuals are seen more commonly by health services. Over the last decade, much research has suggested that, to classify overweight individuals accurately with respect to health risks, both BMI and an indicator of fat distribution must be considered. Traditionally, this indicator has been waist: hip circumference ratio. However, it is increasingly clear that this complex classification of BMI and waist:hip ratio is not a powerful tool in health promotion and may be replaced by a classification based on waist circumference alone (see page 14).
Increased Moderately increased Severely increased Very severely increased
1
of low socioeconomic status. The prevalence increases with age until about 70 years, then declines. Obesity is also common in other parts of the world. Relatively high prevalences are found in the former socialist economies of Eastern Europe and Latin America, and in the Caribbean, the Middle East and North African countries. Recent trend data suggest that the very high prevalence of obesity seen in some former socialist economies of Europe (as high as 45% in women in parts of Russia and Lithuania) may be declining, but other reports show that obesity is still increasing in Latin America, the Caribbean and the Middle East. Obesity is uncommon in sub-Saharan Africa, China and India, though the prevalence seems to be increasing, particularly in affluent populations in larger cities. In these countries, both undernutrition and overnutrition are increasing; this is related to growing inequalities in income and access to food.
Prevalence Estimates of the prevalence of obesity are uncertain because of lack of data, differences between countries within the same region, and secular trends. Taking the mid-point of the estimates (Figure 2) gives a figure of about 250 million obese adults worldwide (about 7% of the total adult population). The true prevalence of obesity is likely to be about 5–10%. In most countries, the prevalence of overweight (BMI 25–30 kg/m2) is about two to three times as great as the prevalence of obesity; thus, as many as 1 billion individuals may be overweight or obese. It has been demonstrated in many reviews that obesity (BMI ≥ 30 kg/m2) is common in most countries with established market economies and is increasing (Figures 3 and 4), but the prevalence and rate of increase varies between and within these countries; for example, in France, the prevalence is 10% in Toulouse and 22% in Strasbourg. Obesity is usually more common in those
Costs of obesity Overweight and obesity are likely to be major contributors to total health care costs in affluent societies, but there is an urgent need for better data on all sources of costs associated with obesity. Such data are vital for efforts to convince governments and health professionals about the importance of the problem of overweight and obesity in social and economic terms, and they may help improve the cost-effectiveness of strategies for the management and prevention of obesity. Direct costs (Figure 5) Direct costs comprise costs to the community from diversion of resources to the treatment of obesity, and the cost of diagnosis and treatment of diseases associated with obesity. Direct costs vary between countries because of differences in: • the prevalence of obesity • the definition of obesity and the reference population (different BMI cut-off points used) • relative risks of obesity-related illnesses • costs of diagnosis and treatment of obesity-related illnesses • methods used to calculate the costs. Two methods have been used to calculate the direct costs of obesity:
Jacob C Seidell is Head of the Department of Chronic Diseases Epidemiology at the National Institute of Public Health, Bilthoven, Netherlands, and Honorary Professor in the Department of Nutrition at the University of Glasgow, UK. He trained in nutrition and epidemiology in Wageningen, Netherlands. His main research interest is obesity.
MEDICINE
Associated health risks Low (but risk of other clinical problems increased) Average
5
© 2003 The Medicine Publishing Company Ltd
OBESITY
Estimated world prevalence of obesity
• • • • • • • •
Established market economies Former socialist economies India China Other Asian countries Sub-Saharan Africa Latin America and Caribbean Middle East
Population aged ≥ 15 years (millions) 640 330 535 825 430 276 280 300
Prevalence of obesity (%) 15–20 20–25 0.5–1.0 0.5–1.0 1–3 0.5–1.0 5–10 5–10
Approximate estimate (with mid-point) of number of obese individuals (millions) 96–128 (112) 66–83 (75) 3–7 (5) 4–8 (6) 4–12 (8) 1–3 (2) 14–28 (21) 15–30 (22)
3616
World
(251)
Source: Murray C J L, Lopez A D. The Global Burden of Disease. Cambridge: Harvard University Press, 1996.
2
• the fraction of incidence of diseases attributable to obesity multiplied by the costs of these diseases – total direct costs are the sum of these costs • the fraction of use of medical care attributable to obesity (e.g. excess consultations with general practitioners and medical specialists, excess hospitalization, excess medication) – total direct costs are the sum of these costs. Despite these differences, most estimates are about 2–8% of total health-care costs. It has also been shown that the direct costs associated with overweight (BMI 25–30 kg/m2) are about double the direct costs associated with obesity (BMI > 30 kg/m2). However, these calculations are crude and involve assumptions
that may lead to an overestimation of the costs of obesity (e.g. neglect of adjustment for social class), or underestimation (e.g. many diseases are excluded from the calculation, the definition of obesity is usually narrow). Indirect costs Indirect costs of obesity are related to loss of productivity through absenteeism, provision of disability pensions and premature death. There is a lack of good economic analysis in this field, though research from Sweden, Finland and the Netherlands shows that obesity is associated with increased sick leave and need for disability pensions (Figure 6). In obese
Prevalence of obesity in women
25
25
20
20
Obese women (%)
Obese men (%)
Prevalence of obesity in men
15
10
5
15
10
5
0
19 78 19 79 19 80 19 81 19 82 19 83 19 84 19 85 19 86 19 87 19 88 19 89 19 90 19 91 19 92 19 93 19 94 19 95 19 96
19 78 19 79 19 80 19 81 19 82 19 83 19 84 19 85 19 86 19 87 19 88 19 89 19 90 19 91 19 92 19 93 19 94 19 95 19 96
0
Year USA Germany
Year UK Netherlands
USA Germany 4
3
MEDICINE
UK Netherlands
6
© 2003 The Medicine Publishing Company Ltd
OBESITY
Direct costs of obesity
• • • • •
USA USA Australia Netherlands France
1986 1988 1990 1989 1992
Definition of obesity 2
BMI > 29 kg/m BMI > 29 kg/m2 BMI > 30 kg/m2 BMI > 25 kg/m2 BMI > 27 kg/m2
Percentage of health care costs 5.5 7.8 2 4 2
2.2
Men Women
2.0
Relative risk compared to BMI < 22.5 kg/m2
Year
Provision of disability pensions and BMI in Finnish adults
Most costs are additonal to those incurred at BMI 22–23 kg/m2
1.8
1.6
1.4
1.2
5 1.0
Finns, chronic cardiovascular disease and musculoskeletal disorders increase the likelihood of receiving a disability pension. The likelihood of receiving a disability pension for respiratory diseases is increased in very lean individuals, but this probably reflects the underlying relationship between heavy smoking and leanness. In a group of Dutch civil servants, obese men and women (BMI > 30 kg/m2) were more likely to be absent from work for all medical reasons combined, as well as for more specific problems (psychological and musculoskeletal disorders).
2. 5 >3
2. 4 .0 –3 30
27 .5 –
29
.9
.4 25
.0 –
27
.9 24
BMI (kg/m2) Source: Rissanen A et al. BMJ 1990; 301: 835–7.
6
• costs of adaptations to a larger body size (e.g. tailormade clothing for larger sizes, adaptations to furniture) • costs of weight management/control (in the USA, $30 billion per year is spent on weight-loss remedies). The costs of obesity for an obese individual may be only partly reflected in economic costs, however; there are also consequences in terms of diminished social functioning and quality of life. Knowledge about the relationship between obesity and diminished social, mental and physical functioning and economic situation is limited.
Personal costs Some direct and indirect costs may be paid partly by society and partly by individuals; the proportions vary between countries and between individuals. Increasingly, in European countries, a minimum cost related to treatment of illness is paid by patients. Insurance policies covering health-care costs vary in their reimbursement strategies. Obese individuals may earn less than their lean counterparts even when earnings are corrected for intellectual ability and social background. One prospective study showed that overweight young women (aged 16–24 years at baseline) had completed fewer years of school, were less likely to be married, had lower household incomes and experienced higher rates of household poverty than women who were not overweight after 7 years of follow-up. These results were independent of baseline socioeconomic status and aptitude test scores. Prospective studies in Denmark and the USA confirmed that obesity in young adults determines lower social class attainment and income. The relationship between social class and obesity is complex, and it has been proposed that there may be common underlying genetic causes that may promote obesity and tend to reduce social class. However, discrimination against obese young adults has been well documented and remains the most likely explanation for these observations. Other excess costs for obese individuals may include: • additional costs of health and life insurance • costs of adaptation to impaired physical functioning – the strong relationship between obesity and difficulty performing activities of daily life (e.g. carrying groceries, climbing stairs, bending and kneeling, walking, bathing, dressing) means that obese individuals may need paid or unpaid assistance
MEDICINE
22 .5 –
<2
2. 5
0.8
FURTHER READING Bulpitt C J, Battersby C, Palmer A J et al. Association of Symptoms of Type 2 Diabetic Patients with Severity of Disease, Obesity and Blood Pressure. Diabetes Care 1998; 21: 111–15. Gortmaker S L, Must A, Perrin J M et al. Social and Economic Consequences of Overweight in Adolescence and Young Adulthood. N Engl J Med 1993; 329: 1008–12. Lean M E J, Han T S, Seidell J C. Impairment of Health and Quality of Life in Men and Women with a Large Waist. Lancet 1998; 351: 853–6. Seidell J C. Time Trends in Obesity: An Epidemiological Perspective. Horm Metab Res 1997; 29: 155–8. Seidell J C, Flegal K M. Assessing Obesity: Classification and Epidemiology. Br Med Bull 1997; 53: 238–52. Sjöström L, Narbro K, Sjöström D. Costs and Benefits when Treating Obesity. Int J Obes 1995; 19: (Suppl. 6): S9–12. WHO. Obesity: Preventing and Managing the Global Epidemic. Geneva: WHO, 1998.
7
© 2003 The Medicine Publishing Company Ltd