Global Burden of Disease 2023 is officially released

The Global Burden of Disease Study (GBD) is the most comprehensive assessment of health trends and conditions across countries. GBD provides detailed analysis of disease burden related to life expectancy, non-communicable diseases, mental health, and many other health topics. We discuss the latest GBD with IHME Director Dr. Christopher Murray. Read the GBD 2023 capstones, published in The Lancet: • Global demographic analysis: http://ms.spr.ly/6047s2bOv • Global causes of death: http://ms.spr.ly/6040s2bOI • Global burden of diseases, injuries, and risk factors: http://ms.spr.ly/6041s2bOL Access and share all things related to GBD 2023: updated data visualization tools, comprehensive infographics, informative videos, workshops, webinars, and more: https://www.healthdata.org/announcing-launch-gbd-2023-study-results. ________________________ Transcript

Rhonda Stewart: Welcome to Global Health Insights, a podcast from IHME, the Institute for Health Metrics and Evaluation. I’m Rhonda Stewart.

In this episode, we’ll hear from IHME Director Dr. Christopher Murray as he talks about the latest Global Burden of Disease study, also known as GBD.

GBD 2023 is a series of three papers published in The Lancet and presented at the World Health Summit in Berlin. The papers focus on demographic analysis, causes of death, and diseases, injuries, and risk factors. GBD is the largest and most detailed scientific effort undertaken to quantify health trends. GBD provides a unique platform to compare the magnitude of diseases, injuries and risk factors across age groups, sexes, countries, regions, and time.

For decision-makers, the GBD approach provides a unique way to compare countries’ health progress and to understand factors that impact health such as high blood pressure, cancer, and heart disease.

Led by IHME at the University of Washington, GBD is a truly global effort, with more than 16,000 researchers from over 160 countries and territories participating in the most recent update. The latest GBD includes data on topics ranging from life expectancy to mental health to non-communicable diseases.

Chris, the 2023 Global Burden of Disease study covers three capstones published in The Lancet and presented at the World Health Summit in Berlin. The papers cover demographic analysis, causes of death, and diseases, injuries, and risk factors.

Let’s start by talking about the demographic analysis paper. The global age-standardized mortality rate declined significantly since 1950, but that’s only part of the story. What are some of the other key findings from that paper?

Christopher Murray: Well, in the demographic analysis, there’s both the long-term view of progress in expanding life expectancy that has been quite steady, except for the big interruptions due to the HIV epidemic in sub-Saharan Africa as well as the sort of mortality crises in Eastern Europe and Central Asia that occurred in the late 80s and 90s.

But other than those, up to 2019, we had this sort of pattern of progress that we got used to. Then the COVID epidemic came along: 18 million deaths related to COVID and a big drop in life expectancy, and then it really was even worse in 2021 in many countries. And then it bounced back. And so by 2023, we’ve gone in most places back to 2019 levels, but not back yet to the levels we would have expected if the pandemic hadn’t occurred. So that’s one big part of the story.

Another part is the fact that we’ve seen increases in child and adolescent mortality in some parts of the world, particularly some of the high-income countries – the US and Canada stand out. And then we've seen increases in mortality related to drug use disorders, suicides to some extent, in adults that are more in the 25- to 39-year range.

And then there are some changes in methods and data that we now think that younger adult mortality in Africa is higher than we previously thought and older adult mortality is little bit lower than we previously thought.

Rhonda Stewart: And with the causes of death paper, non-communicable diseases (NCDs) account for two-thirds of the world’s mortality and morbidity. What are some of the NCDs that are among the top causes and what accounts for this shift from infectious to noncommunicable diseases?

Christopher Murray: Well, the shift, which is really profound, toward noncommunicable disease causes of healthy life lost, which in the GBD we tend to quantify using a measure called disability-adjusted life years, which reflects premature mortality as well as functional health loss, so this sort of notion of loss of healthy life. And those shifts are very noticeable in lower-middle-income countries and upper-middle-income countries. They’re still occurring in low-income as well, but it’s really profound in the middle-income slice of the world.

So that by 2023, at the top of the list of NCDs and causes of burden is ischemic heart disease. And then the next among the NCDs is stroke, and then diabetes and chronic obstructive pulmonary disease.

And then we get into things that cause functional health loss like low back pain, depression, anxiety,

as other big NCD causes that are going up very substantially. And as we go farther down the list, there are things like lung cancer and chronic kidney disease, Alzheimer’s – these are things that are also going up.

The transition toward NCDs is driven mostly by aging, that the average age of the population gets older in places, mostly because of the declines in fertility. Also, the rates of disease by age have been mostly declining, but declining at a slower rate in the older age groups than population growth. And so you get this more marked shift to NCDs because the rates of progress for the infectious diseases, communicable diseases, as well as maternal and neonatal causes tend to be faster. And so that’s also a contributor to this big transition we’re observing.

Rhonda Stewart: Let’s go back for a second and talk about health loss. So you mentioned health loss and aging. Why is it so important to measure health loss, which is something that other studies really don’t do in the way that GBD does? As people live longer, you’re not necessarily living those years in good health. Why is it important to quantify that?

Christopher Murray: Well, the reason in the 34-year history of the Global Burden of Disease that we’ve always focused on, in addition to reporting standard metrics like death and death rates and causes of death and disease incidence and prevalence, is we roll these up into measures of health loss so that we capture these conditions like mental health disorders, like musculoskeletal disorders,

like drug use, where most of the effect is reducing people’s functional health and not necessarily increasing death rates.

So if you only focus on death, you’re not going to pay attention to things like anxiety and depression and schizophrenia, or back pain, neck pain, that are quite widely experienced and really have a major effect on people’s life. So that’s why we like to look at health loss. When we do look at health loss, there’s a second component to it, which is we’re saying that if you die at a young age, let’s say from an injury at 25, a road traffic injury, that’s a greater loss of health than if you die at 95 from, let’s say, lung cancer.

So we want to capture both the amount of life that somebody’s lost due to premature death, as well as this dimension of things that cause disability or impairment that don’t necessarily kill you. When you do that, you end up with this more complicated, mixed view of what are the leading causes. They include things like back pain or depression. And they also suggest that as lifespan has increased,

We’re not making a lot of progress on reducing the number of years that people live with substantial loss of health function.

Rhonda Stewart: Interesting. And let’s talk about risk factors. So the analysis notes that half of the world’s disease burden is not only preventable, but there are almost 100 modifiable risk factors. What are some of those and how do they contribute to disease burden?

Christopher Murray: Well, the biggest sources of burden, of risk factor–attributable burden,

are a mixture of things that are both behavioral, metabolic, and environmental. At the top is high blood pressure. It’s the number one risk factor around the world. And then that accounts for, as a percent of health loss, more than 8% of all burden is related to high blood pressure.

And then we have, as number two, we have particulate air pollution, both indoor and outdoor, and that’s also slightly over 8% of all burden. And then we fall into a behavioral risk, which is smoking, as number three, and then high blood sugar is number four. Then low birth weight and short gestation, a

critical risk for neonatal death, comes in at number five.

Obesity and overweight is number six. And then we get into kidney dysfunction, high cholesterol,

child growth failure. And interestingly now, which is sort of new for GBD 2023 in the top 10 is lead.

And that’s a change from previous assessments, that lead is now so prominent.

Rhonda Stewart: Okay, let’s go back for a second to some of the things you mentioned about anxiety and depression. The latest GBD provides really important information on mental health. Tell us about some of those findings.

Christopher Murray: Well, mental health as a share of health loss is going up quite steadily around the world. And there’s a sort of steady rise that started in some countries. We can see that rise starting around 2010.

But there was a big jump in anxiety and depression during COVID And although it’s come down somewhat after COVID, it has not come down to the sort of pre-COVID levels. And so there is this rise in the burden of mental health disorders.

A lot of controversy as to what’s driving that, with theories ranging from device use, cell phone use, social media use, and then exacerbated by COVID lockdowns for children particularly. But it’s very hard to get a definitive answer. What we see in the data is that things are getting worse, and that trend started before COVID and is certainly made worse by COVID.

Rhonda Stewart: It’s important to note that although IHME coordinates the GBD, the work is carried out by a global network of almost 16,000 researchers. What does their participation add to the study?

Christopher Murray: Well, we take a very collaborative approach to the burden of disease and have done now for at least the last 16, 17 years of the study. And the reason that the network of collaborators matter so much is in multiple dimensions. So first, they find and contribute data that we might not know about, whether that’s a local study on the prevalence of depression or something on tobacco use. You know, there’s a broad array of studies that are often not part of one of the well-known global datasets like the Demographic and Health Surveys. So they identify and contribute important datasets.

The collaborators help interpret data, giving that local knowledge that’s so critical. Like if there was a certain survey, they didn’t go to two provinces in a country because they were war-torn or because the rainy season was particularly challenging, or other biases that might exist in data sources for a particular country. And so that local insight, local knowledge is really essential.

Then they help interpret the modeling process where we take all the raw data that’s out there on every health condition and over time and then use models to iron out fluctuations in the data or inconsistency across studies or make estimates where in years where we don’t have studies or data, and the Collaborators help in making sure those models pass the sort of face validity test – do they match local insight and understanding.

And then lastly, they play a key role in writing papers, interpreting the results, thinking about local policy implications. And that’s why in addition to the capstones that we’re publishing now, we will follow suit with hundreds, or now with each cycle of GBD, thousands of reports and papers written by the Collaborators covering local regional disease-specific, risk-specific patterns that emerged from the study.

Rhonda Stewart: And new data sources and new modeling methods have helped to expand the depth and the breadth of the latest GBD, contributing to the results that you’ve been talking about. Tell us about that.

Christopher Murray: Well, you know, one of the important aspects of the Global Burden of Disease study is we are collectively across the collaboration always looking for ways to enhance the quality of the analysis. And so that’s, as we discussed, new datasets, but it’s also capturing methods innovation.

So for this cycle, some of the main innovations have included a new approach to measuring or estimating all-cause mortality by age and sex that is much more driven by the data and does not use anymore what has always been a feature of demographic analysis, a thing called model life tables –that the original ones date back to the 1960s and they’ve been periodically revised and have a heavy influence on, for example, what we did in the past or what the UN Population Division or WHO does for life expectancy and age-specific mortality.

And now we have very much a statistically driven empirical approach that doesn’t depend as much or at all on these model life tables. And that’s, for example, contributed to our understanding that mortality in some parts of sub-Saharan Africa is higher at younger adult ages and lower at older adult ages as an example.

Other innovations, we’ve added as we do each round, some new causes. So we’ve added some of the thyroid diseases, we’ve added electrocution as a cause of injury, and a number of other causes have been broken into more detailed categories. We’ve very substantially revised the outcomes related to some key risks, particularly sexual violence against children, where the data is now there for many more risks, outcomes, diseases than we had previously appreciated. and as I mentioned earlier, a pretty big change in our understanding of lead, driven in that case by new data.

But it does reflect our commitment to use the Burden of Proof methods to always be looking at what is the evidence base on the relationship between the risk exposure and particular disease outcomes.

Rhonda Stewart: There are numerous examples of how GBD has been used by policymakers and others. You mentioned that one of the things that’s so useful about the Collaborator Network is their ability to gather information that might be policy-relevant at a local level. So what value does the GBD have for evidence-based decision-making by policymakers and other decision-makers?

Christopher Murray: You know, primarily what the GBD provides is the broad comparative view for a country or a region or a province where it’s done subnationally of what are the biggest diseases and injuries, and are they getting worse, are they getting better, what are the biggest risk factors – that can become the targets for public health action.

We’ve looked at how people are using in government, particularly the GBD. And so we’ve been trying to examine, how the user base out there is making use of the GBD. And it’s very interesting because what you find is thousands, actually, of examples of governments in reports, in policy analyses, using the GBD for a range of activities, priority setting, formulating strategic plans, using the current and future burden that comes from forecasting to plan human resource development – you know, what specialties, for example, to train – using the GBD for agenda setting to identify problems that maybe government hasn’t really tackled or had a plan for, but look to be large problems and therefore warrant policy review and formulation. And then some explicit examples where the results are used to push through policy change or legislation.

Examples are tobacco and alcohol, but others as well where governments have used the results to argue in parliaments and legislatures for legislation to tackle a risk or a disease.

So a pretty innovative, diverse set of uses. And we keep learning about more and more ways that the GBD is used to enhance resource allocation or prioritization.

Rhonda Stewart: Great. Well, thanks so much, Chris.

Christopher Murray: Okay, thank you.

Rhonda Stewart: Details about the Global Burden of Disease study and a wide range of GBD-related resources can be found at healthdata.org. ________________________ An independent population health research organization based at the University of Washington School of Medicine, the Institute for Health Metrics and Evaluation (IHME) works with collaborators around the world to develop timely, relevant, and scientifically valid evidence that illuminates the state of health everywhere. In making our research available and approachable, we aim to inform health policy and practice in pursuit of our vision: all people living long lives in full health. Learn more about IHME. Where to follow us:

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