The number of deaths and illnesses due to metabolic risks has increased since 2000

The latest results from the 2021 Global Burden of Diseases, Injuries and Risk Factors (GBD) study, published in The Lancet, provide new evidence on health problems and the risk factors that cause them.

The increasing number of people exposed to metabolic risk factors such as high systolic blood pressure (SBP), high fasting plasma glucose (FPG), high body mass index (BMI), high LDL cholesterol and kidney dysfunction demonstrates the consequences of population ageing and lifestyle changes on a global scale.

According to the study, there was a 49.4% increase in global DALYs, or disability-adjusted life years (years of healthy life lost due to ill health and premature death), associated with metabolic risk factors between 2000 and 2021.

During this period, poor health among people aged 15 to 49 was increasingly associated with high BMI and high fasting plasma glucose (FPG), also known as high blood sugar, which increases the risk of developing diabetes. Other metabolic risk factors, such as high SBP and high LDL cholesterol, also made the top 10 risk factors for people in this age group.

"While these risk factors are metabolic in nature, their development can often be driven by a variety of lifestyle factors, especially among younger generations," said Dr. Michael Brauer, an associate professor at the Institute for Health Metrics and Evaluation (IHME).

"They also point to an ageing population that is more likely to develop these conditions over time. Targeting preventable noncommunicable diseases through modifiable risk factors represents a huge opportunity to proactively change the trajectory of global health through policy and education."

The GBD risk factor analysis provides comprehensive estimates of the burden of disease for 88 risk factors and their associated health outcomes for 204 countries and territories from 1990 to 2021. For the first time, the GBD study incorporates IHME's new "burden of evidence" methodology, which rigorously evaluates the evidence linking risk factors, diseases, and injuries, and offers an additional perspective for prioritizing action and identifying areas requiring further research.

Particulate air pollution, smoking, low birth weight and short gestational age were also among the largest contributors to DALYs in 2021, with significant variations by age, sex and location.

The study found that significant progress has been made between 2000 and 2021 in reducing the global burden of disease associated with maternal and child health risk factors; unsafe water, sanitation and hand hygiene; and indoor air pollution from cooking with solid fuels.

"Risk factors that currently lead to poor health, such as obesity and other components of metabolic syndrome, exposure to ambient particulate matter, and smoking, must be addressed through a combination of global health policy and exposure reduction efforts to mitigate health risks and improve population health," said Dr. Emmanuela Gakidou, professor of health metrics sciences at IHME.

"With increasing exposure to risk factors such as high blood sugar, high blood pressure, low physical activity and diets high in sugar-sweetened beverages, there is an urgent need for interventions targeting obesity and metabolic syndromes," said Dr. Greg Roth, director of the Cardiovascular Health Evaluation Program and adjunct assistant professor of health metrics sciences at IHME.

"GBD highlights that future trends may differ significantly from the past due to factors such as climate change and rising rates of obesity and addiction, but at the same time, there is enormous opportunity to change the trajectory of health in the next generation," said Dr. Lian Ong, a leading researcher at IHME.

The largest reductions in disease burden occurred for risk factors related to maternal and child health, unsafe water, sanitation and hand hygiene, driven by both reduced exposure levels and proportionately smaller populations of infants and young people.

These figures demonstrate that public health interventions and humanitarian health initiatives over the past three decades have been successful, with particularly high rates of reduction in the burden associated with these risk factors in regions with low levels on the Sociodemographic Index, measures of income, fertility and education.

A significant reduction was found in the global burden of disease associated with risk factors for child and maternal undernutrition, such as child stunting, with a 71.5% reduction in age-standardized DALYs between 2000 and 2021, and low birth weight and short gestational age, with a 33.0% reduction over the same period.

The authors found that despite the global decline, the disease burden associated with risk factors for child and maternal undernutrition remained high in the GBD super-regions of sub-Saharan Africa, South Asia, parts of North Africa and the Middle East, and parts of South-East Asia, East Asia and Oceania.

The disease burden associated with unsafe water sources, unsafe sanitation and lack of access to handwashing facilities (all in the top 25 risks) declined, with age-standardised DALY reductions of 66.3%, 69.2% and 65.7%, respectively.

In contrast, the burden of smoking (age-standardized risk-related DALYs) has increased modestly due to population ageing, despite declining levels of exposure to this risk factor. The burden of disease (age-standardized risk-related DALYs) associated with particulate air pollution, high BMI, high FPG, and high SBP has increased significantly as exposure to these risk factors has increased and the population has aged.

Also published in The Lancet was a GBD projection study for 204 countries from 2022 to 2050, indicating that global life expectancy is likely to increase between 2022 and 2050.