The Demographics: Mortality and Population research team is developing and advancing methods for quantifying fundamental indicators of population health. Through country-specific estimates of premature mortality by age and sex, we can begin to address the causes of premature death. The ideal method to capture death data is a vital registration system where all deaths in a population are documented. However, less than half (approximately 44%) of the world’s population has their births and deaths recorded in a vital registration system.
In the absence of such systems, mortality estimates must be derived from other sources of data, such as censuses and surveys. IHME compiles and synthesizes data across each of these types of sources and systematically generates estimates of mortality levels for 187 countries since 1970. Providing comparable estimates of mortality rates is necessary to help inform global and national health policy and research aimed at preventing premature deaths in both children and adults.
Key Activities
- Improve demographic estimation methods
We are developing new methods to improve data collection, analysis, and estimation, particularly in the areas of survey design, forecasting, synthesis of data from multiple sources, and single-source data analysis (including death distribution, birth histories, and sibling/parental survival). For example, we have fielded household surveys as part of the Population Health Metrics Research Consortium (PHMRC) in an effort to refine sibling survival and parental survival methods, and have developed and tested alternative methods for mortality forecasting.
Currently, IHME relies upon population estimates generated by the United Nations Population Division. To ensure the highest internal consistency among results, IHME must produce its own population estimates. The research team will draw upon lessons learned from developing the methods used to derive mortality estimates and incorporate these advancements into improved methods for population estimation. The team will need to undertake a full systematic analysis of fertility data to produce these estimates.
- Produce global, regional, and country-level estimates of mortality
We continually update our mortality database as new data sources become available. We incorporate all available data sources to generate global, regional, and country-level estimates of key indicators of child mortality, adult mortality, and life expectancy at birth. In addition to key indicators, we also produce age- and sex-specific mortality estimates for the full age spectrum from birth to 85 and older for both sexes.
Continual assessments of progress toward reaching international targets for child mortality reduction are essential for decision-makers. The research team is currently updating our estimates of under-5 mortality, integrating new data and further improving our methods to meet that need. In 2007, 2010, and 2011, IHME released estimates for under-5 mortality that show an accelerated rate of decline in under-5 mortality in 13 regions in the world, including all regions in sub-Saharan Africa. For the first time in recent history, the number of children dying worldwide has fallen below 8 million.
- Produce subnational mortality estimates
Subnational estimates of mortality by age and sex are an important input into national policy debates. In Brazil, we generated infant mortality estimates at the microregion and municipality levels from 2000 to 2010. We faced two main methodological challenges: vital registration is incomplete in many places, and the small size of many microregions and municipalities may lead to unstable estimates of mortality rates. The research team addressed the gaps in these data by comparing under-5 mortality from surveys and censuses with data from birth and death registries and using a small area model to make mortality rate estimates more reliable, even with small sample sizes.
Given the health disparities that exist within large populations, the Demographics: Mortality and Population research team is currently producing mortality estimates for several countries, including Zambia, India, China, and the United States. We expect that significant differences will be revealed from one locality to the next within each of these countries, highlighting inequalities resulting from a range of factors, such as socioeconomic and geographic indicators.
- Develop new model life tables
Many global health applications require life tables, which show the probability that a person at a given age will die before his or her next birthday in a specific population for each age and sex. Current model life table systems lack an integrated process to generate life tables for populations affected by HIV/AIDS, which has greatly altered the mortality trends of numerous countries, and they generally lack the capability to provide life tables with plausible time trends. For example, if one life table has a higher summary mortality index for people between the ages of 15 and 60, then the estimated age-specific mortality rates for age groups between 15 and 60 should also be higher. The research team has developed a new model life table system that will be used to generate full life tables for all countries from 1970 to 2010.
Select activities by the Demographics: Mortality and Population research team support the Global Burden of Diseases, Injuries, and Risk Factors 2010 Study, producing estimates measuring the impact of hundreds of diseases, injuries, and risk factors in 21 regions around the world.
Impact
We continue to refine new demographic methods to provide systematic and comparable mortality estimates for the global health community. In the future, we plan to use these mortality estimates along with other data sources to produce a series of population estimates.
