global burden of disease
Every human being has an equal right to a healthy life. To realize this, advocates and policymakers need a comprehensive understanding of factors that are detrimental to health, and how these factors vary across populations. Global Burden of Disease (G B D) is a measure of total health loss from hundreds of diseases and injuries (and their risk factors) that provides insight into the health status of different populations throughout the world
definition of GBD
What illnesses and health problems are out there
WHO divides the global burden of disease into 3 categories → 1. non-communicable diseases (chronic conditions like heart disease, cancer), 2. communicable diseases (contagious diseases caused by infectious agents) which includes maternal health and nutrition, 3. injuries
As diet changes and people live longer, we are getting more non-communicable diseases like cancer and heart disease
The whole idea of global burden of disease is looking at trends where things become more common and where they are less common, as a way to help find interventions and ways to decrease the global burden of disease
Global Burden of Disease Study
- The Global Burden of Disease (G B D) Study tabulates all available information about the causes of deaths and disability in the world and DALYs are used to report on the health status of countries across the globe
- The G B D study is an ongoing endeavor that quantifies the burden of premature mortality and disability for major diseases or disease groups by countries. Data can be broken down by age, sex, and race
Video: Global Burden of Disease Study
In the 1990s, health scientists Alan Lopez and Christopher Murray sought to improve global health measurement beyond basic birth and death data. They developed the Global Burden of Disease (GBD) study, which standardized health data from around the world to quantify the causes of illness and death. The study, first published in 1997, has since grown into a massive, ongoing collaboration involving over 2,600 researchers from 140 countries. It aims to answer key health questions and guide policy, influencing decisions globally, from government spending to research priorities. The GBD has led to significant policy changes and contributed to over 16,000 publications. It helps determine the most pressing health problems, track progress, and project future trends, making it a critical tool in public health. Thanks to continued funding, the GBD remains a valuable resource for improving global health outcomes.
Health Categories Used to Report GBD
The GBD tool organizes diseases and illnesses into three main groups. Group 1 includes communicable diseases, and maternal, neonatal, and nutritional conditions. Non-communicable diseases form Group 2, and Group 3 encompasses Injuries. The GBD numbers and findings are continually updated by WHO researchers. Findings from the 2019 GBD Study provide valuable information about the status of global health at that time
Communicable Diseases, & Maternal, Neonatal, Perinatal, & Nutritional Conditions
- Communicable, maternal, neonatal, perinatal, and nutritional disorders (e.g. tuberculosis, H I V, malaria) represent 2 out of every 10 deaths that occur globally
- These conditions, occur largely in low-income populations due to inadequate access to healthcare, particularly preventative care.
- Although the global rate of death is estimated at 20%, the rate is 50% in low socio-demographic index (S D I) regions, and only 5% in high S D I region
Non-Communicable Diseases
- Non-Communicable Diseases (N C Ds) (e.g. coronary artery disease, cancer, mental illness) account for about 7 out of 10 deaths globally. This means that out of the three health categories, the majority of deaths are due to non-communicable diseases.
- Despite accounting for roughly 70% of deaths globally, many of the lower S D I (social development index) countries do not have a rate this high. In 2019 NCDs were responsible for 41% of deaths in low S D I regions, and 88% in high SDI regions
- Lower SDI regions → typically poorer or less developed countries
- Higher SDI regions → wealthier or more developed countries
- Smaller or poorer countries may have fewer NCD-related deaths because they are still dealing with infectious diseases or other health issues that are more common in lower-income areas. As countries become wealthier and healthier, the prevalence of NCDs tends to increase, as seen in the higher SDI regions.
Injuries
- Injuries (e.g. car crashes, suicide, and war injuries) represent roughly 1 in 10 deaths that occur globally
- This category represents the largest difference between the sexes, with injuries accounting for 12% of overall male deaths and 6% of female deaths in 2019.
Reflecting on Racial and Ethnic Differences in Death Rates
The largest difference between the sexes with respect to death rates occurs in the injury category of G B D. In Canada, 10,957 men and 6,414 women died as a result of injury in 2015, which follows the results of the G B D. Additionally, First Nations, Inuit, and Metis populations are 3.5, 3.2, and 2.7 times more likely to die, respectively, by injury than the general population in Canad
Why might Canadian Indigenous populations be more at risk of dying by injury?
Typically, men engage in more unsafe behaviour and employment than women, and are less likely to be protected by someone else, whereas women might be protected by their brother, father, etc. Indigenous populations may be less likely to seek or receive poor medical treatment when injured as a result of stigma and historical oppression
Comparing High Socio-Demographic Index (SDI) and Low SDI Countries
Differences in G B D between high and low socio-demographic (S D I) countries are often explored in research and policy creation. The S D I takes into account the income per person, educational attainment, and fertility rate
how SDI relates to causes of death
The Socio-Demographic Index (SDI), which combines income, education, and fertility rates, offers a more accurate measure of a country’s development and health than traditional labels like “developed” or “developing.” The 2015 Global Burden of Disease study used SDI to show that, as countries develop, life expectancy increases and causes of death shift from infectious diseases and maternal mortality in low SDI regions to non-communicable diseases like heart disease and cancer in high SDI regions. It also highlights how mortality shocks, like wars and natural disasters, can cause sudden spikes in deaths. The study emphasizes the importance of understanding both the age profile and the causes of death to guide global health policies.
Disability Adjusted Life Years (DALYs)
Disability Adjusted Life Years (DALY) is a measure of overall disease burden, which is expressed as the cumulative number of years lost due to ill-health, disability, or early death
Years Lived with Disability (YLD)
- To incorporate disability and mortality into a single measure of burden, Years Lived with Disability (YLD) is used
- YLD multiplies the number of years a person has a condition that affects their quality of life. Each condition has a weighting factor between 0 and 1, 0 being perfect health and 1 being death. The rating is indicative of the degree to which a disease negatively impacts an individual’s life
Different disability weighting factors
0: perfect health
0.10: chronic insomnia
0.20: congestive health failure
0.41: multiple sclerosis
0.59: blindness
0.66: alzheimer’s dementia
1: death
Years of Life Lost (YLL)
- Years of Life Lost (Y L L) is the second component of the DALY measure. This measure of premature mortality has two defining characteristics.
YLL = (# of Deaths) x (Life Expectancy - Age of Death)
- Ultimately, the YLL equation places more weight on illnesses that result in early mortality because dying young has a bigger impact on both the individual and society at large
GBD Compare Tool
The Institute for Health Metrics and Evaluation (I H M E) created an interactive tool to analyze global health trends from 1990 to present. This tool enables you to see how patterns of disease change over time and to compare disease trends by country, age, and sex
The Institute for Health Metrics and Evaluation (I H M E)
An independent population health
research center at U W Medicine, part of the University of Washington, that provides rigorous and
comparable measurement of the world’s most important health problems and evaluates the strategies
used to address them. I H M E makes this information freely available so that policymakers have the
evidence they need to make informed decisions about how to allocate resources to best improve
population health
How have the global DALYs of each disease changed from 2005 to 2019?
DALYs of H I V, tuberculosis, and malaria have decreased, while DALYs of depression and ischemic heart disease have increased
What trends do you see in the three health categories from 1990 to 2019? Hypothesize why these trends might have occurred.
During this time period, the percentage for DALYs/100,000 for non-communicable diseases (blue) significantly increased, while the DALYs/100,000 for communicable diseases (red) decreased. Injuries (green) remained third. However, all three categories experienced a decrease in DALYs/100,000.
Comparing Death Rates to DALYs
- What do you notice about IHD when you compare its death rates to its DALYs? How would you explain these results?
- IHD has a large death rate (16.7% of total deaths) but a smaller proportion of the DALYs (7.19% of total DALYs). IHD is often characterized by an acute life-threatening episode. As a result, it has a high proportion of deaths when compared to proportion of Y L Ds, creating a smaller DALY score
Comparing High SDI and Low SDI Countries
- What differences do you notice in death rates between high and low S D I countries? What are some possible explanations for these differences?
- When comparing the rates between high and low SDI countries, it appears that in the low SDI countries more deaths can be attributed to communicable diseases, such as tuberculosis. Meanwhile, high SDI countries have more deaths attributed to non-communicable diseases, such as breast cancer. The death rates in low and high SDI countries that are attributed to injuries, appear comparable.
- Some of the reasons for these differences in death rates are because of the life expectancy difference, and the access to and quality of healthcare. Because life expectancy is longer in high SDI countries, more deaths can be attributed to non-communicable disease like coronary artery disease, which is impact by stress and other lifestyle factors. Meanwhile, in low SDI countries, life expectancy is lower and the access to healthcare is more limited, leading to more death being attributed to non-communicable diseases like tuberculosis, which can be more easily treated in high SDI countries
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