On Thursday, 12/13/2012, The Lancet published seven papers with the results of the Global Burden of Diseases, Injuries and Risk Factors Study 2010. The epic, 5-year study involved hundreds of collaborators to compile and analyze all available data on health outcomes globally. My role in the project focused on finding and obtaining input data, managing data at IHME, and creating visualizations. This is the first in a series of blog posts in which I’ll discuss the sources of data used in the different components of the study, the availability of health outcomes data in general, and the metrics that were generated, and share some stories from the trenches. This post provides an introduction to the study. Follow me on Twitter or subscribe to my RSS feed to find out about future installments on mortality, causes of death, non-fatal health outcomes, and covariates.
The Global Burden of Diseases, Injuries and Risk factors Study 2010 (GBD 2010) is arguably the most comprehensive assessment on human health ever conducted. Richard Horton, Editor of The Lancet, and Peter Piot, Director of the London School of Hygiene and Tropical Medicine, compared the GBD 2010 to the Human Genome Project in terms of scope and importance. The results were published by The Lancet in seven papers that took up an entire triple issue of the journal. It's the first time in the 189-year history of the Lancet that an entire issue was dedicated to one study (the Lancet was founded in 1823
). The results were officially presented at a launch event at the Royal Society in London last week (picture on the left).
GBD 2010 was coordinated by the Institute for Health Metrics and Evaluation (IHME) – my employer – in collaboration with 6 other organizations, the University of Queensland, Harvard School of Public Health, Johns Hopkins Bloomberg School of Public Health, the University of Tokyo, Imperial College London, and the World Health Organization (WHO). Professors Christopher Murray, director of IHME, and Alan Lopez, head of the school of population health at the University of Queensland, developed approach and methodology for global burden of disease analysis in the 1990s, and oversaw this iteration with a complete revision of all the steps of the analytic process (on the right, editor-in-chief of The Lancet Richard Horton is taking a picture of Chris and Alan at the GBD Study 2010 press conference).
GBD 2010 mapped all known diseases and injuries to 291 causes that were then analyzed for the burden they caused through fatal and non-fatal outcomes. This required compiling and analyzing all available
published and unpublished data and evidence on health outcomes (notice that available is in italics? More on that later). Data sources include censuses, surveys, vital statistics, disease registries, hospital records, and many more. Especially for non-fatal outcomes and risk factors, systematic literature reviews were a key source of data. Hundreds of researchers provided data and expertise, and the seven published papers included 486 authors from over 50 countries. The analysis encompassed 18 different components that are highly interconnected (see the overview paper
Compiling these data was a monumental task, but analyzing the overall global burden provided a key advantage compared to studies that focus on one or few diseases or injuries. There are 235 causes that can lead to death, and in GBD 2010, deaths from these causes always sum up to all-cause mortality in each age-sex-region group, i.e. every death is counted only once or - in scientific terms - all-cause mortality estimates constrain the cause-specific estimates. Studies that estimate mortality for only one or few causes don’t have this constrain and will often provide higher numbers of death.
A key challenge for all parts of this study was the availability of input data (this is the main reason for me to write this series). For many developed countries, data to estimate mortality and non-fatal health outcomes by cause and risk factors are readily available. However, in many of the 187 countries that are part of the 21 GBD regions, these data are not being collected, incomplete, of poor quality, insufficiently documented, only available on paper, or stuck on obsolete storage media. In addition, data are often simply not being shared for political or other reasons, even for this kind of research that provides a global public good. A fundamental take-away from this study is that we need to improve the collection and distribution of health-related data, in developing but also developed countries. For mortality data, this means improving civil registration and vital statistics systems to make sure that we track every death and its cause everywhere in the world. Survey, census and other health-related data are just as important for governments to share. With regard to understanding non-fatal health outcomes, access to health record, disease registry and other detailed health data is essential, of course with proper attention to privacy, confidentiality, and consent of the individuals. All of these can be overcome but that requires commitment and political will by the data owners.
GBD 2010 compiled all data on health outcomes available to us. For the first time ever, we now have estimates on mortality and non-fatal health outcomes by cause and risk factor that were developed with a consistent methodology for several points in time (1990, 2005, and 2010). To provide information about the availability and consistency of input data, 95% uncertainty intervals were calculated at each step, propagated throughout the analytic process, and are available for all results. GBD 2010 provides estimates even for causes, risk factors, regions, or age groups where data was limited or no data was available; these were imputed using different statistical methods and covariates like GDP, education, and many others to inform the estimates. We believe that estimates based on limited data are better for policy and decision making than no evidence at all. The result is a gigantic database with structured results by age and sex that are comparable across geographies and time, all publicly available. The data will allow global health practitioners, policy makers, donors, media, researchers and others to explore patterns and trends in health over time.
Here are your key resources to explore further: