The best evidence-based health policies are made on the basis of thorough and regular updates of the global burden of disease. Aid agencies need to know how and where to target their funding and monitor impact. Knowledge of what sickens and kills people can help health-care providers and researchers to tailor their priorities to needs and to long-term trends in the health of populations. Yet in many poor areas of the world, basic systems such as death certification are lacking, and quality health-care data are scarce and scattered. At national, regional and global levels, collection of comprehensive health metrics is too often the poor cousin in health care and in health research. The result is a shortage of high-quality, comparable and readily accessible data.

For these reasons, the publication in The Lancet last week of the Global Burden of Disease 2010 study (GBD 2010) should be applauded. The study is an unprecedented five-year effort by hundreds of researchers in dozens of countries worldwide, who made a huge effort to track down, collate and analyse surveys, as well as published and unpublished health-care data. Led by the Institute for Health Metrics and Evaluation at the University of Washington in Seattle, they have produced a vast smorgasbord of global estimates of the burden of multiple diseases, injuries, risk factors and chronic complications (see page 322).

The findings capture the world’s health status in impressive detail, and highlight significant trends, including how, in almost all countries, life expectancies are rapidly converging towards the long lives previously enjoyed only by the richest. The study also charts the demise of major causes of global health burden such as infectious diseases and maternal and child mortality, although these continue to blight many poorer countries, particularly in sub-Saharan Africa.

People benefit from longer lives but they are increasingly experiencing a downside. They spend many of those extra years in ill health, often with more than one illness, which creates large costs for health-care systems. The study found that age-related illnesses include not only the usual suspects such as cancers and heart disease, but also a host of conditions that rarely kill but often disable, such as mental illness and musculoskeletal disorders.

The GBD 2010 should be required reading for health leaders and research administrators.

Health-care systems and research agendas must adapt accordingly; for example, health-care providers must learn how to manage the high costs of tackling this new disease landscape. The GBD 2010 should be required reading for health leaders and research administrators, and should lead them to re-examine how well current research portfolios match emerging trends in the burden of sickness and disease.

The GBD 2010 is far from perfect. Some of the underlying data are weak — for example, they may be scarce, unreliable or unstandardized — and in places the study relies heavily on sophisticated modelling to eke out meaning. To its credit, it has tried to provide transparency in the form of quantitative indicators as to the robustness — or otherwise — of each of its estimates. Given such caveats, some of its findings will inevitably be dubious. Malaria researchers have vigorously contested the GBD’s assertion earlier this year that malaria killed twice as many people in 2010 as previously thought, but the study stands by its data (see Nature;2012).

Such disagreements are inevitable in any complex, large-scale, international collaborative undertaking of this kind, particularly in areas where uncertainties in the data are highest. Such health metrics are also highly political, because they can affect the direction of national and international health-care and research funds, where there is much turf to fight over. But, ultimately, the findings of the GBD 2010, however imperfect, provide a robust basis and analytical framework for further research and health policies that is better than anything that went before. That its findings and methodologies will be challenged and debated in the months and years to come is not only healthy, but how science works. The way forward is to rework and build on the foundations that have been laid.