The Burden of Disease research team aims to provide comparable estimates of the impact of diseases and injuries to inform priorities for policies, funding, and further research. Individual indicators about health conditions – such as the total number of deaths by age and sex, or the incidence of particular conditions – are useful but insufficient to understand the real impact of a given condition on a population.
To assess the burden of disease, both mortality and morbidity must be taken into account using the disability-adjusted life year (DALY). The DALY is a time-based measure that combines years of life lost due to premature mortality and years of life lost due to time lived in health states of less than ideal health.
Much of the research conducted by this team feeds into the Global Burden of Diseases, Injuries, and Risk Factors Study 2010, which is a complete systematic assessment of the data on all diseases and injuries, producing comprehensive and comparable estimates in DALYs for 1990, 2005, and 2010. IHME is leading the study with collaborators from Harvard University, Johns Hopkins University, the University of Queensland, the World Health Organization, and 800 condition-specific experts from around the world.
Other IHME research teams producing research for this study include Causes of Death, Demographics: Mortality and Population, Risk Factors, and Functional Health Status. By approaching each condition in the same way and analyzing all available data, this effort will produce the most highly comparable and methodologically-advanced set of burden estimates available, so that decision-makers have the evidence they need to design the best prevention and treatment programs.
Key Activities
- Produce estimates of incidence and prevalence for all conditions using DisMod III
A systematic and global effort is underway as part of the Global Burden of Diseases (GBD) Study 2010 to collect all available information on incidence, prevalence, duration, remission, and mortality for 220 conditions.
Once these data are collated, we assess whether the observations are internally consistent. For some conditions, we can derive numbers of incident cases directly from disease registers, routine databases, and epidemiological studies, but for many other diseases, only prevalence data are available.
We often need to estimate average duration from known rates of remission or death for a particular condition. To do this, the research team has developed DisMod III, a computer software program that allows the user to check if a set of assumptions on incidence, prevalence, remission, case-fatality rates, and observed mortality rates are consistent with one another.
DisMod III, which will be used to analyze all relevant conditions, allows users to calibrate the number and size of the age groups for input and output variables as required, supplement available data with expert knowledge, and force the estimates to be internally consistent.
- Produce a new analytic engine to calculate DALYs
To produce final estimates, software is needed to systematically calculate DALYs. The DALYnator combines estimates from CoDMod (which produces years of life lost) and DisMod (which produces years lived with disability) with health state severity weights to produce estimates of disease burden (in DALYs) with an appropriate degree of uncertainty.
The DALYnator tracks the uncertainty intervals around all of these measurements, ensuring that the resulting outputs accurately reflect the confidence of the predictions. The DALYnator also considers complications that arise in calculating health state severity measures for conditions that are often comorbid.
- Produce burden estimates for all conditions and risk factors
The Burden of Disease research team's work supports the ultimate goal of the GBD Study 2010, to produce estimates of disease burden for 220 conditions and nearly 40 risk factors by age and sex in 21 regions of the world for 1990, 2005, and 2010.
- Develop instruments and methods to assess incidence and prevalence of key conditions in populations
Population-level incidence and prevalence of chronic conditions are often poorly understood because of a lack of data. A validated population-based survey providing accurate information on such conditions could be a cost-effective way to fill significant data gaps. As part of the Population Health Metrics Research Consortium Mexico Study, the research team has fielded a survey instrument in Mexico City.
To validate the instrument, the study ties the surveys back to verified clinical information about individuals interviewed about conditions of interest, including angina pectoris, chronic obstructive pulmonary disease, asthma, depression, vision loss, hearing loss, cirrhosis of the liver, osteoarthritis, rheumatoid arthritis, and cataracts.
Drawing from the lessons learned through the analysis of verbal autopsies, the research team is developing a new method, the Symptom Diagnosis Method, to analyze the collected data.
Impact
Improving the health and well-being of the world’s population is a moral imperative and is essential for global stability and progress. The vast energies, technologies, and resources pouring into global health have given us the capacity to reduce disease, improve health conditions, and address deep inequalities in health between populations. The Burden of Disease research team provides tools and knowledge to inform efforts for making effective interventions possible.
