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World Health Report 2002 (WHR 2002), the World Health Organisation's premier publication, discusses the latest evidence on risks to public health, how these risks are perceived, measured and communicated and explores solutions available to governments and others to reduce and prevent these risks. It highlights the growing recognition for greater international cooperation in the design of comparable indicators and in standardising the measurement and assessment of risk factors.

Risk, as discussed in the World Health Report 2002, is a probability of an adverse outcome, or a factor that raises this probability. Of course, the number of risks that exist in the world is enormous and not all are as risky as others. The WHR 2002 focuses on the ten risks that cause the most damage to health, in terms of death and disability. They are:

This document focuses on WHR 2002 and noncommunicable diseases (NCDs). Cardiovascular disease, cancers, diabetes, chronic respiratory disease and are the most common NCD's. Levels of risk for NCDs involve people's patterns of behaviour, determined by the interplay between personal characteristics, social interactions and many environmental factors. Individual behaviour is only part of the problem. The WHR 2002 points out that poverty, violence, rapid social and economic changes, lack of education, inadequate or total absence of health services contribute as much to the increasing cases of NCDs as they do to AIDS, malaria and tuberculosis. This shift reflects a significant change in diet habits, physical activity levels, and tobacco consumption worldwide as a result of industrialisation, urbanisation, economic development and food market globalisation. People are consuming a more energy-dense diet high in fat and are less physically active. Processed foods have increased the variety and quality of food available globally, as well as facilitating social and workplace changes. But many processed foods are high in sugar, excessively salty, or contain high levels of saturated fats.

Despite strong evidence of the magnitude of this burden and the preventability of its causes, not to mention the threat it poses to already strained health systems, national and global action remain inadequate. The globalisation of the production and marketing campaigns of the tobacco and food industries exemplify the challenges to policy makers and public health practitioners. A full range of policy responses is required. Unfortunately the capacity and resources for this response are limited. This nutrition transition and increasing physical inactivity is taking place in developing countries at a much faster pace than was the case for the developed world. As a consequence, risk factor levels have risen dramatically in poorer countries. Unless effective action is taken, NCDs and deaths will inexorably continue to increase.

In developed countries NCD risk factors constitute seven of the 10 leading risk factors contributing to the burden of disease, six of 10 among low mortality developing countries, and three of 10 in high mortality developing countries. In most developing countries, trends for most NCD risk factors over the last decade portend a massive increase in the occurrence of NCDs over the next two decades.

1. Attributable burden of disease (DALYs)

High mortality developing countries (38.2% world population) are characterised by the dominance of three major risks: underweight: unsafe sex; unsafe water; food, sanitation and hygiene. For these risk factors there are minimal differences by sex. Additional important risk factors include indoor smoke; lack of breastfeeding; and micronutrient deficiencies.

For low mortality developing countries (39.6% of the world's population), the distribution of risk factors is more complex and more differentiated by sex. Alcohol, tobacco and high blood pressure are most prominent for men; with high blood pressure: underweight and overweight being most important for women.

Among many developing countries (22.2% of the world's population) tobacco and alcohol dominate for men. For men and women, high blood pressure, high cholesterol, being overweight, low fruit and vegetable intake and lack of physical activity are all major contributors to the burden. Tobacco is also a major risk factor for women.

2. Attributable mortality

In comparing the burden of disease data to mortality, the above comments still apply, but the global impact of a few major risks emerges starkly:

Low mortality developing countries have a risk factor profile closer to that of developing countries with respect to the above mentioned risks.

This document provides a brief overview of some of the salient points in the WHR 2002. It seeks to explain which risk factors are the most important in the world today as concerns NCDs, how people understand these risks to their health and how the public health community approaches concepts of risk and works to reduce and prevent these risks.

The WHR 2002 was preceded by several national and international consultations on the subject of risk. These culminated in a series of roundtables on risk at the 55th World Health Assembly (WHA 2002) in May 2002. Several ministers of health and senior government officials, gathered in Geneva, testified to the need to address NCDs in a comprehensive manner. WHA 2002 also mandated WHO to develop a Global Strategy on Diet, Physical Activity and Health over the next two years, a process which is now underway in consultation with all stakeholders. This document seeks to add its voice to that nascent call to redress the imbalance of investments - research, policy, resources - in NCD's.

Discussion

Which actions, conditions, circumstances and decisions endanger health? To what extent? What can be done to protect health against these factors? How does this apply to an individual and the population at large? The answers to these questions can only be sought in a complex intersection of science, influence, opinion, and subjectivity.

The risk factors that are most often found in rich countries, not unlike those found in poor countries, are related to patterns of living—how people are obliged to live or how they choose to live. Risk factors associated with over-consumption are lethal in their own right.

Among NCD risk factors, some have already emerged as major killers, requiring urgent action. These include tobacco use, high blood pressure, high cholesterol, being overweight, low fruit and vegetable intake, inadequate physical activity and excessive alcohol consumption.

Tobacco

According to WHR 2002, scientific uncertainty should not be allowed to delay the control of large and important risk factors given the evidence that substantial future reductions could be achieved. Tobacco control is an example where prevention has been given a very high priority, as in South Africa, Thailand and Brazil, and where valuable gains for public health have already been registered.

Cessation and prevention are the foundation upon which the world's first public health treaty, the Framework Convention on Tobacco Control, currently under negotiation among WHO's 191 Member States, is built. The FCTC will act as a pathfinder in tobacco to advance national public health policies shielded from the risk of being undermined by transnational phenomena, including internet-based marketing and advertising and smuggling.

Tobacco use kills 4.2 million people every year. This figure has nearly doubled in the last ten years and it is estimated to reach 8.4 million by 2020 if action is not taken now to curb the tobacco epidemic. The four hundred and seventy-nine deaths per hour, or one every 7.5 seconds, from cardiovascular disease, chronic respiratory disease, cancer and other diseases caused by tobacco is a reality that has economic and social consequences beyond what is currently appreciated.

Obesity, overweight, high blood pressure, high cholesterol

There are more than a billion adults in the world who are overweight and 300 million who are clinically obese. In North America and Western Europe, about half a million people die every year from obesity-related diseases. Overweight and obesity lead to adverse changes in metabolism, including unhealthy levels of blood pressure and cholesterol and resistance to insulin. Obesity has also been associated with asthma and lower lung function. High blood pressure and high blood cholesterol are most often caused and/or aggravated by eating too much fatty, salty and sugary foods. Overweight and obesity raise the risk of cardiovascular disease, which accounts for one out of every three deaths in the world, as well as diabetes and many cancers.

There are about 600 million people with high blood pressure in the world. Most of them are unaware and undiagnosed. High blood pressure and cholesterol are major risk factors of cardiovascular disease. Overweight and obesity raise the risk of diabetes, cardiovascular disease and many cancers. Obesity has also been associated with asthma and impaired lower lung function.

Diet also relates to health through other mechanisms. An intake of high saturated fats (animal fat) and low unsaturated fat (from vegetable oils), raises blood cholesterol, a powerful risk factor for CVDs. A high salt intake raises blood pressure, irrespective of weight. A diet high in fruit, vegetables and whole grains, not only reduces the risk of obesity, but is also protective through other mechanisms. Finally, physical activity not only helps maintain normal weight, but has a multiple impact in helping resist NCDs.

Alcohol

Alcohol consumption has increased in recent decades, mostly in developed countries. Alcohol causes 1.7 million deaths and 56 million disability-adjusted life years lost (DALYs) a year. It is estimated that alcohol causes 20-30% of oesophageal cancer, liver cancer, cirrhosis of the liver, homicide, epilepsy, motor vehicle accidents, and other intentional injuries.

While a list that outlines the top ten risk factors may seem straightforward, the fact is that the risk story is very complicated. First, while each of these risks has an important impact on health, they rarely manifest themselves individually. Their effects are compounded and become even more lethal when they co-exist—when an individual or a community is exposed to several risks together.

Another issue that must be taken into consideration is how the public perceives risks. Social, cultural and economic factors are central to how individuals perceive every aspect of their world—including the risks to their health. By the same token, it would be irresponsible to presume that the countless diverse groups that make up a given community or population might understand the risks that surround them in the same way, or more importantly, that they might share the same views about risk with health practitioners or public health professionals.

A number of contemporary trends greatly influence the existence of risks to health in the modern world, and how they are perceived. Global debates sparked by the power and influence of special interest groups associated with corporate, often multinational, business interests and the juxtaposed efforts of many advocacy coalitions and public health groups to educate and promote policies that prioritise the public good have become central to any serious consideration of public health policy.

Parallel to this phenomenon, the ever-growing power and reach of mass media and new forms of communication have created a platform for messages of all types to be transmitted in a way rarely witnessed before.

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The way forward

The WHR 2002 explains that in constructing health policies for the prevention of well-known risks, choices need to be made between different strategies. For instance, will preventing small risks in large populations avoid more adverse health outcomes than avoiding large risks in a smaller number of high risk individuals? What priority should be given to cost-effective interventions for primary rather than secondary prevention, such as lowering blood pressure distribution by reducing salt intake compared to treatment of people with high blood pressure? For example, policy-makers might need to analyse cost-effectiveness of lowering the blood pressure distribution of the whole population through reducing salt intake versus pharmacological treatment of high risk individuals only. Or the value of lowering cardiovascular risk by promoting healthy diets and physical activity through policy interventions compared to expensive bypass surgery. In the case of tobacco control, the question might compare tobacco product tax increases or advertising bans to cessation programmes.

Decisions also have to be made with regard to comprehensive risk factor approaches that address tobacco use, diet, physical inactivity, high blood pressure, and high blood cholesterol together; as opposed to single risk factor interventions (treating blood pressure or cholesterol alone) as the latter is much less effective both in terms of costs and outcomes.

What priority should be given to cost-effective interventions to primary prevention rather than expensive approaches to secondary prevention? The optimal mix of interventions depends on the underlying economic, political and social reality of specific countries. Implementing these interventions requires strong and sustained political commitment that places health above special interests.

What are these interventions?

Advocacy for healthy public policy frames the issues and creates public support for action. For example, WHO has worked to reframe the tobacco debate in profound ways. We have put the spotlight on tobacco industry behavior and shown that unless we address this, progress will be slow.

Many aspects of successful health policy require legislation and regulation. For risks like alcohol and tobacco use this includes laws to ban tobacco advertising and sponsorship, stop tobacco and alcohol sales to young people, and food labeling regulations.

For Diet, Physical Activity and Health, WHO recognises that the causes of NCDs are complex and because of this, the response needs to be multi-faceted and multi-institutional. The evidence is overwhelming that prevention is possible when sustained actions are directed both at individuals and families, as well as the broader social, economic and cultural determinants of NCD. All stakeholders have a role to play in encouraging the consumption of healthier food and more physical activity.

Governments, health professionals, the food and advertising industries, and wider civil society should contribute to making the easy choices the healthy choices, both for diet and physical activity. WHO recognizes that there is a range of possible interventions by the public and private sectors, and is committed to keeping its member states informed of effective means to accomplish these goals.

Missed opportunities in health care services abound. With the help of health care personnel, patients can adopt behaviours that prevent the onset of NCD, or reduce their complications. For example, advice to TB patients to quit smoking or informing diabetics on the importance of physical activity. However, patients need knowledge, motivation, and skills to stop using tobacco products, to eat a proper diet, and to engage in regular physical activity. Prevention and health promotion should be part of every visit to health care service providers, but this is far from routine clinical care.

Beyond interventions and policies, the WHR 2002 underscores the need for trust in order to reduce risks--trust in sources of information, and trust in the information itself. While no government or health agency can reduce risk to zero, it is incumbent upon them to deliver information about risks to health to their constituencies. Important lessons in risk communications are detailed in the WHR 2002. For example, risk communicators should release a full account of the known facts. Governments and public agencies are often tempted to present simplified explanations. Political credibility and public trust are rapidly lost if the public believes it has not been given the full information on the risks that affect them.

Risk factors of today translate into the deaths and diseases of tomorrow. Early action saves lives and money. The impact of risk factors has a cumulative effect on people's lifespan starting in early childhood. Combined with adverse social and economic factors, this impact grows exponentially.

If the definition of risk is about power, the communication of risk is about trust. Public health professionals, health care practitioners, NGOs, media, governments and the private sector have to earn that trust.

For more information about the World Health Report 2002 or to order the Report, please visit the WHO website.