The World Health Report 2002 represents one of the largest research projects ever undertaken by the World Health Organization. In collaborating with experts worldwide, WHO has collected and analyzed evidence that will have implications for global health for many years to come. Although the report carries some ominous warnings, it also opens the door to a healthier future for all countries -- if they are prepared to act boldly now.
The report describes the amount of disease, disability and death in the world today that can be attributed to a selected number of the most important risks to human health. This is of great interest in itself but, more importantly, the report also calculates how much of this present burden could be avoided in the next couple of decades if the same risk factors were reduced from now onwards.
Furthermore, it shows how some of those possible reductions can be achieved in a range of cost-effective ways. The ultimate goal is to help governments of all countries to raise the healthy life expectancy of their populations. The report says that very substantial health gains can be made for relatively modest expenditures. It suggests that at least an extra decade of healthy life could be within the grasp of the populations of many of the world's poorest countries. Even the people of the most industrialized countries, such as the United States of America, the Western European nations and those of the Asian Pacific, stand to gain another five years or so of healthy life.
Although there are many possible definitions of the word "risk", it is defined in this report as "a probability of an adverse outcome, or a factor that raises this probability". The number of such factors is countless and the report does not attempt to be comprehensive. For example, some important risk factors associated with infectious diseases, such as viruses, bacteria, and antimicrobial resistance, are not included. Instead the report concentrates on a selection of risk factors -- real risks to health, and often the actual causes of major diseases -- for which the means to reduce them are known, and produces some startling findings about their true impact.
From this selected group, the report identifies the top ten risks, globally and regionally, in terms of the burden of disease they cause. The ten leading risk factors globally are: underweight; unsafe sex; high blood pressure; tobacco consumption; alcohol consumption; unsafe water, sanitation and hygiene; iron deficiency; indoor smoke from solid fuels; high cholesterol; and obesity. Together, these account for more than one-third of all deaths worldwide.
The report shows that a relatively small number of risks cause a huge number of premature deaths and account for a very large share of the global burden of disease.
For example, at least 30% of all disease burden occurring in many developing countries, such as those in sub-Saharan Africa and South-East Asia, results from fewer than five of the ten risks listed above. Underweight alone accounts for over three million childhood deaths a year in developing countries.
In other, more developed, countries such as China and most countries in Central and South America, five risk factors cause at least one-sixth of their total disease burden. At the same time in the most industrialized countries of North America, Europe and the Asian Pacific, at least one-third of all disease burden is caused by tobacco, alcohol, blood pressure, cholesterol and obesity. Furthermore, more than three-quarters of cardiovascular disease -- the world's leading cause of death -- results from tobacco use, high blood pressure or cholesterol, or their combination. Overall, cholesterol causes more than 4 million premature deaths a year, tobacco causes almost 5 million, and blood pressure causes 7 million.
The report identifies a number of cost-effective interventions to counter some of the risk factors. In the report, an intervention is defined broadly as "any health action -- any promotive, preventive, curative or rehabilitative activity where the primary intent is to improve health". According to the report, the impact of many of the risk factors can be reversed quickly, and most benefits will accrue within a decade. Even modest changes in risk factor levels could bring about large benefits.
In order to know which interventions and strategies to use, governments must first be able to assess and compare the magnitude of risks accurately. The subject of risk assessment is thus a major component of this report. Risk assessment is defined as "a systematic approach to estimating the burden of disease and injury due to different risks".
The report makes key recommendations to help countries develop risk reduction policies which, if implemented, will result in substantially more years of healthy life for many millions of people. At the same time, governments will need to strengthen the scientific and empirical bases for their policies. They will have to improve public dialogue and communications, and develop greater levels of trust for risk prevention among all interested parties. They will also have to develop sound strategies to manage risk uncertainties, and consider carefully a range of ethical and other issues.
Apart from the obvious health benefits, the report says that, overall, reducing major risks to health will promote sustainable development and reduce inequities in society.