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A narrow definition of risk is hampering the search for new methods of tuberculosis control, say Christopher Dye and Mario Raviglione. What factors put people at risk of illness, disability

and death? The answers to this question have far-reaching implications: identifying a risk factor suggests interventions that could avoid or alleviate sickness and suffering. Unfortunately,

for tuberculosis (TB) and other diseases, current risk assessments are not up to the job. > This proposal goes beyond TB: for many causes of ill health, an > unidentified risk is a 

missed opportunity. The Global Burden of Disease Study (GBD) includes an ambitious attempt to pinpoint the major causes of illness worldwide, and to use them to set a global agenda for

preventive health care. But, despite listing 67 risk factors in 10 categories1, the GBD is selective and has little relevance to some important diseases, including TB. A broad set of both

disease determinants and factors that limit disease control and treatment should be included in future studies, with this combined set used as the basis for developing a wider range of

options for disease prevention and care. This proposal goes beyond TB: for many causes of ill health, an unidentified risk is a missed opportunity. BROADER CONCEPTS Most of the risk factors

selected by the GBD are environmental exposures, harmful behaviours, such as alcohol abuse, or physiological abnormalities, such as hypertension or high cholesterol. Only 3 of the 67 factors

listed are linked to TB — tobacco smoke, alcohol abuse and diabetes. And yet there are clearly many other factors that determine who becomes ill or infectious. For example, migration,

urbanization and the way people interact through contact networks are important for the transmission of infection. Genetic factors are also excluded, even though these risks might one day be

managed or treated. But perhaps the most significant drawback of the GBD and similar risk assessments is that they do not consider the limitations of current interventions as avoidable

risks. In TB control, these limitations include poor awareness of symptoms, lack of access to diagnostic and treatment facilities, the prohibitive cost of drugs to treat multidrug-resistant

strains, medical malpractice, poor quality of care from health workers, broken drug supply chains, and patients not completing their treatment. Although these shortcomings are not

conventionally thought of as risk factors, they account for a large proportion of the avertible burden of disease. To choose the best options for disease control, their importance must be

considered next to conventional TB risk factors such as overcrowded housing, diabetes, tobacco smoking, HIV co-infection and under-nutrition. We need, in short, to adopt a more comprehensive

view of risk. ADVERSITY INTO OPPORTUNITY Finding new ways to reduce TB is a global health priority, and expanding the concept of risk will generate more options for control. By comparing

the costs and benefits of possible interventions, we can prioritize the best among them. For example, in India we recently found that the increases in TB risk from diabetes, malnutrition and

urbanization are modest compared with the expected positive impact of early detection and treatment2. In this setting, the next step is to compare the costs and potential benefits of better

case detection and treatment strategies with those of interventions to mitigate other risk factors. To be comprehensive, this work should go beyond evaluating measures targeted specifically

at TB to look at those that have wider benefits for public health, such as health insurance schemes. In this way, the healthcare profession will be encouraged to evaluate interventions that

could benefit TB but that lie beyond the reach of current disease control programmes. CHANGING THE AGENDA The United Nations (UN) Millennium Development Goals (MDGs) will expire in 2015.

During the MDG era, the rise in the TB incidence rate has been halted and reversed, but the decline is still only a disappointing 2% per year globally3. Effective TB control programmes

should be able to reduce incidence by at least 5–10% each year4 The new UN agenda for international development will probably focus on poverty reduction and sustainable development5. Given

limited resources, the challenge for TB control is to take a broader view of risk, setting priorities that overcome a diverse array of obstacles and exploit all possible opportunities. These

priorities should include better ways to use existing technologies while promoting the most effective new technologies; working closely with the control of non-communicable diseases; and

participating in initiatives to improve health that come not only from the health sector, but also from agriculture, education, finance, industry and housing. This demands a big but

potentially rewarding programme of data collection, quantitative analysis and modelling — one that enlarges the idea of risk to unify TB treatment and prevention, and places both in the

wider context of health and development. REFERENCES * Lim, S. S. et al. _Lancet_ 380, 2224–2260 (2012). Article  Google Scholar  * Dye, C. et al. _PLoS ONE_ 6, e21161 (2011). Article  ADS 

CAS  Google Scholar  * World Health Organization. _Global Tuberculosis Control: WHO Report 2012_ (World Health Organization, 2012). * Dye, C. et al. _Annu. Rev Public Health_ 34, 271–286

(2013). Article  Google Scholar  * United Nations. _A New Global Partnership: Eradicate Poverty And Transform Economies Through Sustainable Development_ (United Nations, 2013). Download

references AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Christopher Dye is Director of Health Information at the World Health Organization, Geneva, Switzerland., Christopher Dye * Mario

Raviglione is Director of the Global Tuberculosis Programme in the HIV/AIDS, Tuberculosis, Malaria & Neglected Tropical Diseases Cluster at the World Health Organization, Geneva,

Switzerland., Mario Raviglione Authors * Christopher Dye View author publications You can also search for this author inPubMed Google Scholar * Mario Raviglione View author publications You

can also search for this author inPubMed Google Scholar CORRESPONDING AUTHORS Correspondence to Christopher Dye or Mario Raviglione. ADDITIONAL INFORMATION _The author(s) alone are

responsible for the views expressed in this article. The article does not necessarily represent the decisions, policy or views of the WHO. The WHO retains copyright_. RIGHTS AND PERMISSIONS

Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Dye, C., Raviglione, M. Perspective: Weigh all TB risks. _Nature_ 502, S13 (2013). https://doi.org/10.1038/502S13a Download

citation * Published: 09 October 2013 * Issue Date: 10 October 2013 * DOI: https://doi.org/10.1038/502S13a SHARE THIS ARTICLE Anyone you share the following link with will be able to read

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