The goal of this research was to estimate deaths and years of lives lost (YLLs) by age, sex, and region for 235 causes at two points in time – 1990 and 2010. This information can be used to better inform global efforts to assess whether society is or is not making progress in reducing the burden of premature – and especially avoidable – mortality.
Capturing and sharing reliable and timely information on the leading causes of death and how they are changing has been a major analytical challenge. Too often, we have not known with any certainty which diseases or ailments contribute to death. For example, of the more than 50 million deaths each year in the world, less than 40% get a death certificate certified by a physician.
All available data on causes of death for 187 countries from 1980 to 2010 from vital registration, verbal autopsies, mortality surveillance, censuses, surveys, hospitals, police records, and mortuary records were identified. Data quality was assessed for completeness, accuracy, missing data, variations, and probable causes of death. Six different modelling strategies were employed to estimate cause‐specific mortality trends. Strategies differed depending on whether a disease or ailment was rarely associated with deaths, a frequent cause of deaths, or somewhere in between.
The world is witnessing a huge shift in leading causes from premature death from communicable, maternal, neonatal, and nutritional causes toward noncommunicable diseases. The most important driver of this shift is aging – not population growth. Age‐specific death rates for most causes are actually declining. The declines for communicable, maternal, neonatal, and nutritional causes are greater than for noncommunicable causes and injuries.
In 1990, 34% of all deaths were due to communicable, neonatal, and maternal causes. By 2010, though, these largely preventable conditions accounted for one‐quarter (13 million) of the 52.8 million deaths that year. The annual number of deaths from noncommunicable diseases, by contrast, rose by over 8 million, to 34.5 million, or two out of every three deaths in 2010.
There are important variations in what is causing the greatest number of YLLs across regions:
- The causes that rank highest in global rankings of YLLs, such as lower respiratory diseases, ischemic heart disease, and stroke, are in the top 10 causes of premature death in almost all regions in 2010.
- The massive impact of HIV/AIDS on mortality in most developing regions can be seen in how it ranks in 2010, with north Africa and Middle East, east Asia, central Asia, and southern Latin America being notable exceptions.
- Malaria is a leading global cause but a minor cause in most regions outside sub‐Saharan Africa and Oceania.
- Road injury is a remarkably consistent cause of YLLs. Its lowest regional ranking is 19th in Oceania and it is in the top five causes in eight regions.
- All the neonatal causes and tuberculosis are important causes in some developing regions but relatively minor causes in many regions.
- Suicide is a top ten cause in the eight regions with the most advanced health transition. Other causes that seem to be strongly related to the epidemiological and demographic transition include colorectal cancer, breast cancer, pancreas cancer, brain cancer, non‐Hodgkin’s lymphoma, Alzheimer’s disease, kidney cancer, and prostate cancer.
The world has done a tremendous job battling infectious diseases such as HIV and malaria. The burden from these diseases rose until 2004, and now is coming down. After more than 15 years of increasing death rates, global deaths from HIV fell from 1.7 million in 2006 to 1.5 million in 2010, a 12% drop. Malaria deaths have fallen from 1.5 million in 2005 to 1.2 million in 2010.
While many more children live past the age of 5 now than in 1990, some diseases persist as high causes of child death, particularly lower respiratory infections, diarrhea, and neonatal causes. Nearly 900,000 children continue to die from rotavirus, HiB, pneumococcal pneumonia, meningitis, and other diseases for which effective vaccines are available.
These successes have been tempered by a dramatic rise in the number of deaths from noncommunicable diseases. Four of the top five leading causes of death in 2010 were noncommunicable: ischemic heart disease (first), stroke (second), chronic obstructive pulmonary disease (third), and lung cancer (fifth). Ischemic heart disease and stroke together killed 12.9 million people in 2010, or 1 in 4 deaths worldwide, compared with 1 in 5 in 1990. Of the leading causes of death, diabetes mellitus is the fastest growing globally. Diabetes was responsible for 1.3 million deaths in 2010, which is twice as many as in 1990.
The world is making good progress in fighting some cancers, but others are beating back the best scientific efforts. Eight million people died from cancer in 2010, 38% more than two decades ago; of these, 1.5 million (19%) were from trachea, bronchus, and lung cancer. Liver and stomach cancers combined now cause nearly as much death and as trachea, bronchus, and lung cancers. Colorectal cancer is causing a significant burden globally.
The proportion of global deaths due to injuries (5.1 million) was marginally higher in 2010 (9.6%) compared with two decades earlier (8.8%). This was driven by a 46% increase in deaths worldwide due to road traffic accidents (1.3 million in 2010) and a rise in deaths from falls.
These findings highlight the importance of looking more critically and comprehensively at the leading causes of death and YLLs worldwide and how they are changing. Such analyses will be important inputs into discussions about how targets should be set following the conclusion of the Millennium Development Goal period in 2015. These discussions should include effective and affordable prevention of noncommunicable diseases and injuries, as well as their treatment. In addition, there are important regional challenges that need to be addressed. Below are some of the key discussions that should take place as a result of GBD 2010:
- A robust analysis of the way HIV estimates are assessed. We need improved estimation of mortality from HIV/AIDS, malaria, and other causes, including uncertainty. There are too many instances of estimates from large countries, such as Thailand and Nigeria, where the uncertainty intervals are implausibly narrow. By using the GBD approach of ensuring that all causes of death fit inside the envelope of the total number of deaths, we can progress toward better capturing both levels and trends in infectious diseases and their contribution to overall disease burden.
- Further inquiry into the pathogens that cause diarrhea and lower respiratory infections. Specific pathogens as causes of death were added to GBD 2010, which will provide important information for prioritization of existing treatments, such as rotavirus or pneumococcal vaccines, and for the development of future technologies. Studies such as the Global Enterics Multi‐Center Study (GEMS) will provide important additions to our understanding of the relative risks of diarrhea in the presence of different pathogens.
- Looking at the trends from 1990 to 2010 indicates that the MDG‐related YLLs are declining at 2% per year, whereas the non‐MDG‐related YLLs are increasing at 0.8% per year. Population aging, and the substantial if incomplete progress in reducing age‐specific death rates from the MDGrelated causes all suggest that these trends will continue. Indeed, if they do, then non‐MDGrelated causes are likely to account for over two‐thirds (67.6%) of YLLs by 2025. These findings highlight the importance of looking more critically and comprehensively at what are the leading causes of death and YLLs worldwide and how these are changing.
- Our analyses, for the first time, allow such comparative assessments and are important inputs into discussions about goals and targets for the post‐MDG era. The rapid and global rise in premature death from leading noncommunicable diseases argues strongly for inclusion of these conditions and their principle causes in this agenda, particularly given their close relationship to poverty reduction goals. It also stresses the need to understand the effective and affordable options for prevention of noncommunicable diseases and injuries and their treatment, including both medical and surgical interventions.