The Global Burden of Disease (GBD) Study systematically quantifies health loss across the globe. It provides a comprehensive framework for understanding the magnitude of health challenges from various diseases, injuries, and risk factors. This effort helps paint a detailed picture of the world’s health landscape, shedding light on disparities and guiding interventions. The study offers a comparable assessment of health worldwide, providing crucial data for informed public health decision-making.
What the Global Burden of Disease Study Is
The Global Burden of Disease (GBD) Study is a rigorous, systematic endeavor that comprehensively assesses health loss from diseases, injuries, and risk factors. It considers factors such as age, sex, and population over extended periods. Thousands of international researchers collaborate on the study, primarily coordinated by the Institute for Health Metrics and Evaluation (IHME) at the University of Washington.
The GBD Study aims to provide a consistent and comparable evaluation of health conditions across different countries and regions, allowing for a better understanding of global health disparities. It quantifies the impact of hundreds of diseases, injuries, and associated risk factors, with its findings regularly released through the IHME’s website and scientific journals like The Lancet. The latest iteration, GBD 2021, includes data spanning from 1950 to 2021, and specifically accounts for the impacts of the COVID-19 pandemic.
How Health Burden is Measured
The GBD Study employs specific metrics to quantify the burden of disease, with Disability-Adjusted Life Years (DALYs) serving as the primary measure. One DALY represents the loss of one year of healthy life, providing a comprehensive measure of health loss due to a particular cause or risk factor. This metric allows for comparisons across diverse health conditions and populations.
DALYs are comprised of two distinct components: Years of Life Lost (YLLs) and Years Lived with Disability (YLDs). YLLs quantify the years of life lost due to premature mortality, calculated by multiplying the number of deaths from a specific cause by the standard life expectancy at the age of death.
YLDs measure the years lived with disability or health loss due to non-fatal health outcomes. These are calculated by multiplying the prevalence of a condition by its “disability weight,” a numerical score between 0 (full health) and 1 (equivalent to death) that reflects the severity of the disability. By combining YLLs and YLDs, DALYs offer a holistic view of the health burden, encompassing both mortality and morbidity.
How the Study Informs Global Health
The GBD Study provides data that policymakers, researchers, and global health organizations use to identify health priorities and allocate resources effectively. The study’s findings inform health policy decisions and drive improvements in healthcare worldwide. For instance, GBD data has contributed to efforts aimed at reducing child mortality by highlighting specific causes and informing the introduction of vaccines against diseases such as measles and pneumonia.
The data from the GBD Study helps in designing targeted interventions and tracking progress towards health goals. It offers a detailed picture of disease prevalence, incidence, and the health effects of various risk factors, enabling a more precise allocation of resources to address pressing health needs. Countries can use these estimates to benchmark their population’s health against its own historical trends or against other comparable communities globally. The GBD Study also supports assessments of associations between health metrics and other factors, such as workforce headcounts and related costs, informing public health and health service decision-making.
Key Insights from the Study
The GBD Study has revealed significant shifts in global health patterns over time. A prominent trend is the worldwide transition from communicable diseases to non-communicable diseases (NCDs) as leading causes of health burden. In 2021, NCDs were responsible for approximately 43.8 million deaths and 1.73 billion DALYs globally. This represents a substantial portion of non-pandemic-related deaths, with 75% attributed to NCDs in 2021.
Cardiovascular diseases consistently account for the largest share of NCD-related DALYs, followed by cancers, chronic respiratory diseases, and diabetes. For example, cardiovascular diseases had the highest age-standardized DALYs among NCD subtypes across 16 of 21 regions and 159 of 204 countries in 2021. Diabetes and kidney diseases have shown a notable increase, with DALYs more than doubling between 2000 and 2021.
Major risk factors identified by the GBD Study contribute significantly to the overall health burden. High systolic blood pressure, dietary risks, and tobacco usage are among the leading attributable risk factors globally. Elevated blood pressure, for instance, is linked to 25% of global NCD deaths. The study also highlights the increasing impact of high body mass index, which saw a 57.8% increase in its contribution to age-standardized DALYs since 1990. Environmental factors like air pollution also play a role, contributing to millions of deaths globally, primarily from NCDs.