CHAPTER FIVE Some strategies to Reduce risk This chapter puts forward the best available evidence on the cost and effec- tiveness of selected interventions to reduce some of the major risk factors dis- cussed in Chapter Four. It looks at the extent to which these interventions are likely to improve population health, both singly and in combination. It illus trates how decision-makers can begin the policy debate about priorities with information about which interventions would yield the greatest possible im provements in population health for the available resources. The chapter exam ines a range of strategies to reduce different types of risk, and the possible impact of those strategies on costs and effectiveness. Many risk reduction strategi involve a component of behaviour change, and some types of behaviour change might require active government intervention to succeed. Different ways of at- taining the same goal are discussed, for example, the population-wide versus the individual-based approach and prevention versus treatment With regard to policy implications, the chapter concludes that very substantial health gain can be made for relatively modest expenditures on interventions. However, the maximum possible gains for the resources that are available will be attained only through careful consideration of the costs and effects of interventions
Some Strategies to Reduce Risk 99 CHAPTER FIVE ome trategies to educe isk 99 This chapter puts forward the best available evidence on the cost and effectiveness of selected interventions to reduce some of the major risk factors discussed in Chapter Four. It looks at the extent to which these interventions are likely to improve population health, both singly and in combination. It illustrates how decision-makers can begin the policy debate about priorities with information about which interventions would yield the greatest possible improvements in population health for the available resources. The chapter examines a range of strategies to reduce different types of risk, and the possible impact of those strategies on costs and effectiveness. Many risk reduction strategies involve a component of behaviour change, and some types of behaviour change might require active government intervention to succeed. Different ways of attaining the same goal are discussed, for example, the population-wide versus the individual-based approach and prevention versus treatment. With regard to policy implications, the chapter concludes that very substantial health gains can be made for relatively modest expenditures on interventions. However, the maximum possible gains for the resources that are available will be attained only through careful consideration of the costs and effects of interventions.
101 SOME STRATEGIES TO REDUCE RISK FROM HEALTH RISKS TO POLICY arlier chapters have quantified the burden of disease attributable to major risk factors, and shown the size of the potentially avoidable burden if the population distribution of risk is reduced across the board. This knowledge is important but it is only the first step required to decide how best to improve population health with the available resources.The second step involves assessing what types of intervention are available to decrease expo- sure to risks or to minimize the impact of exposure on health; to what extent they are likely to improve population health singly and in combination; and what resources are required to implement them. Chapter 4 quantified the importance of selected risk factors in different settings. This chapter evaluates selected interventions to reduce the impact on population health of some of those risk factors 1 Different types of evidence on intervention costs and effectiveness have been consid ered in the analysis detailed in this chapter. Some interventions have been widely imple mented in many settings, and relatively good information on their costs and effects exists. The interventions for which it is easier to obtain this type of evidence are often those that focus on individuals rather than on populations as a whole, and the overall impact on population health of such interventions can be relatively small. Some types of population based interventions with the potential to make very substantial improvements in popula tion health have not been implemented very frequently or have not been evaluated very often. The evidence on the costs and effectiveness of these interventions is less certain, but it is important to consider them because they have the potential to make very substantial differences in health outcomes Cost-effectiveness analysis can be undertaken in many ways and there have been sev- eral attempts to standardize methods to make results comparable(1-3). WHO has devel oped a standardized set of methods and tools that can be used to analyze the costs and population health impact of current and possible new interventions at the same time(3) As part of WHO,'s CHOiCe project, these tools and methods have been used to analyze a range of interventions that tackle some of the leading risks identified in Chapter 4.2 The ChoiCe project is intended to provide regularly updated databases on the costs and effects of a full range of promotive, preventive, curative and rehabilitative health This chapter represents a report on the first stage of a long-term work plan to evaluate the burden of all the major risks to health and the costs and effectiveness of all major interventions CHOICE stands for CHoosing Interventions that are Cost-Effective- see wwwwho int/evidence
Some Strategies to Reduce Risk 101 5 SOME STRATEGIES TO REDUCE RISK FROM HEALTH RISKS TO POLICY arlier chapters have quantified the burden of disease attributable to major risk factors, and shown the size of the potentially avoidable burden if the population distribution of risk is reduced across the board. This knowledge is important but it is only the first step required to decide how best to improve population health with the available resources. The second step involves assessing what types of intervention are available to decrease exposure to risks or to minimize the impact of exposure on health; to what extent they are likely to improve population health singly and in combination; and what resources are required to implement them. Chapter 4 quantified the importance of selected risk factors in different settings. This chapter evaluates selected interventions to reduce the impact on population health of some of those risk factors.1 Different types of evidence on intervention costs and effectiveness have been considered in the analysis detailed in this chapter. Some interventions have been widely implemented in many settings, and relatively good information on their costs and effects exists. The interventions for which it is easier to obtain this type of evidence are often those that focus on individuals rather than on populations as a whole, and the overall impact on population health of such interventions can be relatively small. Some types of populationbased interventions with the potential to make very substantial improvements in population health have not been implemented very frequently or have not been evaluated very often. The evidence on the costs and effectiveness of these interventions is less certain, but it is important to consider them because they have the potential to make very substantial differences in health outcomes. Cost-effectiveness analysis can be undertaken in many ways and there have been several attempts to standardize methods to make results comparable (1–3). WHO has developed a standardized set of methods and tools that can be used to analyze the costs and population health impact of current and possible new interventions at the same time (3). As part of WHO’s CHOICE project, these tools and methods have been used to analyze a range of interventions that tackle some of the leading risks identified in Chapter 4.2 The CHOICE project is intended to provide regularly updated databases on the costs and effects of a full range of promotive, preventive, curative and rehabilitative health interventions. 1 This chapter represents a report on the first stage of a long-term work plan to evaluate the burden of all the major risks to health and the costs and effectiveness of all major interventions. 2 CHOICE stands for CHoosing Interventions that are Cost-Effective – see www.who.int/evidence
102 The World Health Report 2002 To answer key policy questions on tackling risks to health, it is necessary to compare the costs and effectiveness of interventions to the situation that would exist if they were not done. This"counterfactualscenario-what would happen in the absence of the interven- tions against a particular risk factor-is different from the counterfactual used in Chapter 4 to estimate the avoidable burden of disease. There the question was what would the bur- den have been if the distribution of risks could be lowered by 25%, 50% or even 100%.That is useful in showing the relative importance of different risk factors, Table 5.1 Leading 10 selected risk factors as percent. but some of these risks can be reduced relatively easily, at low cost, age causes of disease burden measured in DALYs and others cannot. Because health resources are always scarce in re Developing countries lation to need choices must be made about how to allocate them between the substantial number of options available to reduce risks High mortality countries The best way of doing this is to estimate, for each intervention, the Unsafe 10.2%gans in population health and the associated costs compared to the Unsafe water, sanitation and hygiene 5.5% situation that would exist if the intervention were not undertaken. 3 Indoor smoke from solid fuels 3.7% This chapter reports the best available evidence on the cost and Zinc deficiency effectiveness of selected interventions to reduce some of the major Iron deficiency 3. 1% risk factors discussed in Chapter 4. The list of interventions is not Vitamin A deficiency 3.0% exhaustive and the chapter does not include all the risk factors of 2.5% Chapter 4. The ones for which interventions are considered here are 2.0% highlighted in bold type in Table 5.1. A more comprehensive picture 1.9% of interventions concerning diseases as well as additional risk factors Low mortality countries (e.g. alcohol)will be presented in The World Health report 2003 Alcohol 6.29 The analysis is used to identify some interventions that are very Blood pressure 5.0% cost-effective and some that are not cost-effective in different set- Tobacco 4.0% tings It illustrates how decision-makers can begin the policy debate derweight 3.1% about priorities for allocating health resources with information about 7% which interventions have the potential to yield substantial improve 2.1% ments in population health for the available resources. Indoor smoke from solid fuels 1.9% is evidence will be only one input to the final decision about Low fruit and vegetable intake the best combination of interventions. Improving population health Iron deficiency 1.8% is the defining goal of health systems, but there are other social goals Insafe water, sanitation and hygiene 1.79 to which health systems contribute Policy-makers will wish to con- Developed countries sider the impact of different combinations of interventions on health inequalities and poverty and on the responsiveness of their systems, Blood pressure 12. 2%6 for example(4). Communities in different settings might differ in Cholesterol 7. 6%activities, and particular activities might be more difficult to incorpo- 7 49 rate into existing health system infrastructure in some settings than ow fruit and vegetable intake 3.9% in others. The information from this chapter is, therefore, one input Physical inactivity 3.3% a key one, but not the only one-to the policy debate. llicit drugs The analysis does not apply simply to interventions funded by Unsafe sex 0.8% government WHO argues that governments should be good stew- 0.7% ards of their health systems(5). If the population uses interventions Risk factors discussed in this chapter are in bold type that are ineffective, dangerous, or are simply not good value for money, 3 The term"intervention"is used in this chapter in a very broad sense. It includes any health action-any motive, preventive, curative or rehabilitative activity where the primary intent is to improve health. nterventions in the chapter range from the introduction of a tax on tobacco products to treating hyp tension to prevent a heart attack
102 The World Health Report 2002 To answer key policy questions on tackling risks to health, it is necessary to compare the costs and effectiveness of interventions to the situation that would exist if they were not done. This “counterfactual” scenario – what would happen in the absence of the interventions against a particular risk factor – is different from the counterfactual used in Chapter 4 to estimate the avoidable burden of disease. There the question was what would the burden have been if the distribution of risks could be lowered by 25%, 50% or even 100%. That is useful in showing the relative importance of different risk factors, but some of these risks can be reduced relatively easily, at low cost, and others cannot. Because health resources are always scarce in relation to need, choices must be made about how to allocate them between the substantial number of options available to reduce risks. The best way of doing this is to estimate, for each intervention, the gains in population health and the associated costs compared to the situation that would exist if the intervention were not undertaken.3 This chapter reports the best available evidence on the cost and effectiveness of selected interventions to reduce some of the major risk factors discussed in Chapter 4. The list of interventions is not exhaustive and the chapter does not include all the risk factors of Chapter 4. The ones for which interventions are considered here are highlighted in bold type in Table 5.1. A more comprehensive picture of interventions concerning diseases as well as additional risk factors (e.g. alcohol) will be presented in The World Health Report 2003. The analysis is used to identify some interventions that are very cost-effective and some that are not cost-effective in different settings. It illustrates how decision-makers can begin the policy debate about priorities for allocating health resources with information about which interventions have the potential to yield substantial improvements in population health for the available resources. This evidence will be only one input to the final decision about the best combination of interventions. Improving population health is the defining goal of health systems, but there are other social goals to which health systems contribute. Policy-makers will wish to consider the impact of different combinations of interventions on health inequalities and poverty and on the responsiveness of their systems, for example (4). Communities in different settings might differ in their ability and willingness to participate in specific risk-reduction activities, and particular activities might be more difficult to incorporate into existing health system infrastructure in some settings than in others. The information from this chapter is, therefore, one input – a key one, but not the only one – to the policy debate. The analysis does not apply simply to interventions funded by government. WHO argues that governments should be good stewards of their health systems (5). If the population uses interventions that are ineffective, dangerous, or are simply not good value for money, 3 The term “intervention” is used in this chapter in a very broad sense. It includes any health action – any promotive, preventive, curative or rehabilitative activity where the primary intent is to improve health. Interventions in the chapter range from the introduction of a tax on tobacco products to treating hypertension to prevent a heart attack. Table 5.1 Leading 10 selected risk factors as percentage causes of disease burden measured in DALYsa Developing countries High mortality countries Underweight 14.9% Unsafe sex 10.2% Unsafe water, sanitation and hygiene 5.5% Indoor smoke from solid fuels 3.7% Zinc deficiency 3.2% Iron deficiency 3.1% Vitamin A deficiency 3.0% Blood pressure 2.5% Tobacco 2.0% Cholesterol 1.9% Low mortality countries Alcohol 6.2% Blood pressure 5.0% Tobacco 4.0% Underweight 3.1% Overweight 2.7% Cholesterol 2.1% Indoor smoke from solid fuels 1.9% Low fruit and vegetable intake 1.9% Iron deficiency 1.8% Unsafe water, sanitation and hygiene 1.7% Developed countries Tobacco 12.2% Blood pressure 10.9% Alcohol 9.2% Cholesterol 7.6% Overweight 7.4% Low fruit and vegetable intake 3.9% Physical inactivity 3.3% Illicit drugs 1.8% Unsafe sex 0.8% Iron deficiency 0.7% a Risk factors discussed in this chapter are in bold type
Some Strategies to Reduce Risk 103 governments should find ways to encourage people to use resources more appropriately even if the finance is not provided by govemment. The evidence presented in this chapter will facilitate this process WHAT STRATEGIES CAN REDUCE RISKS TO HEALTH? WHO defines the health system to include all actions whose primary intent is to im prove health(5) and some activities that improve health fall outside this definition Exam- ples include reductions in poverty, and improvements in housing and education, which may well reduce exposures to some types of risks but are not primarily designed to improve health. This chapter is concerned mainly with interventions that have the primary intent of proving health. Some interventions, however, are difficult to categorize strictly using this definition. One set that has traditionally fallen within the remit of public health covers improvements to water and sanitation. Many water and sanitation programmes fall outside the health por folio, and clearly such improvements do have considerable amenity value outside health. However, clean water and improved sanitation are considered in this chapter because their attributable burden of disease is so significant. It must be noted, however, that althor they improve health, many of their benefits are not readily incorporated into a cost-effec- tiveness framework and should be considered when comparing them with other types of A number of strategies have been used to reduce health risks that are seen as modifi- able. They can be categorized broadly as interventions that seek to reduce risks in the popu lation as a whole, and those which target individuals within the population. The former include intervention by governments through legislation, tax or financial incentives; engi neering solutions such as the introduction of safety belts in motor vehicles or the provision of piped water; and health promotion campaigns targeting the general public. The latter clude strategies to change health behaviours of individuals, often through personal inter- action with a health provider; and strategies to change the behaviours of health providers, particularly in the way they interact with their clients Genetic screening is a valuable tool for some diseases associated with the risk factors described in this report, but individual genes are not susceptible to m Genetic screening is not considered further in this chapter. RISK REDUCTION AND BEHAVIOUR Many risk reduction strategies involve a component of behaviour change. Even engi neering solutions, such as the provision of piped drinking-water, will not result in health improvements unless people are willing to use the new source. Social scientists argue that behavioural change first requires understanding(6, 7).4 Anumber of individual preferences or characteristics influence how people translate understanding into health behaviours, including how averse to health risks individuals are and how they value possible future health decrements compared with other competing choices in their lives such as wealth and lifestyle. These preferences are influenced by information and the influence of adver- Perceived risk "is the subjective assessment of personal disease risk, based on an indi viduals interpretation of epidemiological and other types of data. There may be a difference In the case of addiction, individuals can struggle to change their behaviours despite recognition of the harmful effects to themselves and others( 8)
Some Strategies to Reduce Risk 103 governments should find ways to encourage people to use resources more appropriately even if the finance is not provided by government. The evidence presented in this chapter will facilitate this process. WHAT STRATEGIES CAN REDUCE RISKS TO HEALTH? WHO defines the health system to include all actions whose primary intent is to improve health (5) and some activities that improve health fall outside this definition. Examples include reductions in poverty, and improvements in housing and education, which may well reduce exposures to some types of risks but are not primarily designed to improve health. This chapter is concerned mainly with interventions that have the primary intent of improving health. Some interventions, however, are difficult to categorize strictly using this definition. One set that has traditionally fallen within the remit of public health covers improvements to water and sanitation. Many water and sanitation programmes fall outside the health portfolio, and clearly such improvements do have considerable amenity value outside health. However, clean water and improved sanitation are considered in this chapter because their attributable burden of disease is so significant. It must be noted, however, that although they improve health, many of their benefits are not readily incorporated into a cost-effectiveness framework and should be considered when comparing them with other types of health interventions. A number of strategies have been used to reduce health risks that are seen as modifiable. They can be categorized broadly as interventions that seek to reduce risks in the population as a whole, and those which target individuals within the population. The former include intervention by governments through legislation, tax or financial incentives; engineering solutions such as the introduction of safety belts in motor vehicles or the provision of piped water; and health promotion campaigns targeting the general public. The latter include strategies to change health behaviours of individuals, often through personal interaction with a health provider; and strategies to change the behaviours of health providers, particularly in the way they interact with their clients. Genetic screening is a valuable tool for some diseases associated with the risk factors described in this report, but individual genes are not susceptible to manipulation at present. Genetic screening is not considered further in this chapter. RISK REDUCTION AND BEHAVIOUR Many risk reduction strategies involve a component of behaviour change. Even engineering solutions, such as the provision of piped drinking-water, will not result in health improvements unless people are willing to use the new source. Social scientists argue that behavioural change first requires understanding (6, 7). 4A number of individual preferences or characteristics influence how people translate understanding into health behaviours, including how averse to health risks individuals are and how they value possible future health decrements compared with other competing choices in their lives such as wealth and lifestyle. These preferences are influenced by information and the influence of advertising and marketing. “Perceived risk” is the subjective assessment of personal disease risk, based on an individual’s interpretation of epidemiological and other types of data. There may be a difference 4 In the case of addiction, individuals can struggle to change their behaviours despite recognition of the harmful effects to themselves and others (8)
104 The World Health Report 2002 between risk perception as an individual and cultural concepts of risk acceptability by soci ty. For example, although driving without a seat belt may be deemed so unacceptable by a ociety that legislation is enacted to enforce it, individuals within that society may perceive the risk to themselves as trivial and choose not to use a seat belt When it comes to risks to health, individuals and societies sometimes prefer to enjoy the benefits of an activity now without thinking about possible future health costs. High con- sumption of certain types of food, for instance, is perceived by some people to give current pleasure despite the risk of harmful health effects-to which they give less weight because they will occur in the future. There is considerable variation in the rate at which people events that might happen in the future. Some research has indicated that smokers"dis- count the future"more highly than non-smokers-for example, a given probability of de veloping lung cancer in 20 years is given less weight by smokers than by non-smokers(9) People who discount the future more highly value a given future health risk less highly than people who discount the future less highly, even if they have the same information The question of how technically to incorporate this into the analysis is discussed later but the effectiveness of behavioural modification interventions is clearly influenced by varia- tions in how people perceive the future A set of additional factors also influences the way people respond to risk-reduction interventions. Even when people have heard and understood the message that insecticide treated nets prevent mosquito bites, and wish to use them to avoid both the nuisance value of mosquitoes and the risk of malaria, a number of factors may prevent them from doing so (10). These include the availability and affordability of nets in their locale and their sleeping arrangements(in a house, or on the street). These in turn will be affected by many factors including personal, community and health system characteristics. One determinant is culture and the social support networks available, sometimes called tem is financed(for example, through social health insurance or user charges)or organized (for example, through managed care or a publicly funded system), also influence beha iours and, through them, the costs and effectiveness of interventions INDIVIDUAL- BASED VERSUS POPULATION APPROACHE TO RISK REDUCTION Two broad approaches to reducing risk were defined earlier. The first is to focus the intervention on the people likely to benefit, or benefit most, from it. The second is to seek to reduce risks in the entire population regardless of each individual's level of risk and poten tial benefits. In some cases, both approaches could be used at the same time. Focusing on high-risk individuals can reduce costs at the population level because an intervention is provided to fewer people, but on the other hand it might also increase the costs of identify the of peop likely to ber Focusing on people who are more likely to benefit has a significant impact on the healtl of a nation only when there are large numbers of them. For example, lowering cholesterol with drugs is effective in reducing overall mortality in a group of people at high risk of leath from heart disease; targeting interventions to reduce cholesterol to the needs of these people focuses the interventions on a group of people likely to benefit. However, only a small percentage of the population is at high risk of death from heart disease at any given time, and only some of them can be identified purely on the basis of
104 The World Health Report 2002 between risk perception as an individual and cultural concepts of risk acceptability by society. For example, although driving without a seat belt may be deemed so unacceptable by a society that legislation is enacted to enforce it, individuals within that society may perceive the risk to themselves as trivial and choose not to use a seat belt. When it comes to risks to health, individuals and societies sometimes prefer to enjoy the benefits of an activity now without thinking about possible future health costs. High consumption of certain types of food, for instance, is perceived by some people to give current pleasure despite the risk of harmful health effects – to which they give less weight because they will occur in the future. There is considerable variation in the rate at which people value and assess adverse events that might happen in the future. Some research has indicated that smokers “discount the future” more highly than non-smokers – for example, a given probability of developing lung cancer in 20 years is given less weight by smokers than by non-smokers (9). People who discount the future more highly value a given future health risk less highly than people who discount the future less highly, even if they have the same information. The question of how technically to incorporate this into the analysis is discussed later but the effectiveness of behavioural modification interventions is clearly influenced by variations in how people perceive the future. A set of additional factors also influences the way people respond to risk-reduction interventions. Even when people have heard and understood the message that insecticidetreated nets prevent mosquito bites, and wish to use them to avoid both the nuisance value of mosquitoes and the risk of malaria, a number of factors may prevent them from doing so (10). These include the availability and affordability of nets in their locale and their sleeping arrangements (in a house, or on the street). These in turn will be affected by many factors including personal, community and health system characteristics. One determinant is culture and the social support networks available, sometimes called social capital. Health system and provider characteristics, such as the way the health system is financed (for example, through social health insurance or user charges) or organized (for example, through managed care or a publicly funded system), also influence behaviours and, through them, the costs and effectiveness of interventions. INDIVIDUAL-BASED VERSUS POPULATION APPROACHES TO RISK REDUCTION Two broad approaches to reducing risk were defined earlier. The first is to focus the intervention on the people likely to benefit, or benefit most, from it. The second is to seek to reduce risks in the entire population regardless of each individual’s level of risk and potential benefits. In some cases, both approaches could be used at the same time. Focusing on high-risk individuals can reduce costs at the population level because an intervention is provided to fewer people, but on the other hand it might also increase the costs of identifying the group of people most likely to benefit. Focusing on people who are more likely to benefit has a significant impact on the health of a nation only when there are large numbers of them. For example, lowering cholesterol with drugs is effective in reducing overall mortality in a group of people at high risk of death from heart disease; targeting interventions to reduce cholesterol to the needs of these people focuses the interventions on a group of people likely to benefit. However, only a small percentage of the population is at high risk of death from heart disease at any given time, and only some of them can be identified purely on the basis of their cholesterol levels. Recent evidence suggests that the group most likely to benefit from