Running for over a decade now, the annual Global Burden of Disease (GBD) study is a giant peer-reviewed assessment of global health trends. The results this year, published across a series of articles in the prestigious journal The Lancet, present some concerning trends, from a worrying plateau in global mortality rates to a decline in global fertility rates.

Coordinated by the Institute for Health Metrics and Evaluation (IHME) at the University of Washington in Seattle, the GBD study offers a fantastically detailed snapshot of the current state of the world's health, involving over 3,500 researchers from 140 countries around the globe.

Population and Fertility

This year, for the first time, the study measured population and fertility data and revealed some pretty fascinating stats for the data nerds out there. Overall, the study found the world's population was increasing annually by over 87 million between 2007 and 2017, however global fertility rates are on the downturn.

Average births per woman have dropped by half since 1950, and over 90 countries are registering rates of less than two births per woman. This generally means that these countries are registering current birth rates at below replacement levels to maintain current populations.

"Although total fertility rates are decreasing," notes Christopher Murray from IHME, "the global population continues to grow as death rates decline and because of population 'momentum' in previous decades."

The majority of countries with decreasing birth rates were found to be in Europe (Georgia, Poland, Romania, Greece, Spain, Portugal), while the highest birth rates were seen in sub-Saharan Africa. Niger represented the highest fertility rate of any country in 2017 with a single woman giving birth to an average of seven children in her lifetime.

"These statistics represent both a 'baby boom' for some nations and a 'baby bust' for others," says Murray. "The lower rates of women's fertility clearly reflect not only access to and availability of reproductive health services, but also many women choosing to delay or forgo giving birth, as well as having more opportunities for education and employment."

Global causes of death

In 2017 there were 55.9 million deaths recorded globally, and over half of those deaths (51.5 percent) could be attributed to four preventable risk factors: high blood pressure, smoking, high blood glucose, and high body mass index.

Going back to 1990, almost all of those top four risk factors were significantly less of a global health issue. In 1990, high body mass index was ranked as just the 16th most significant mortality risk factor, yet in 2017 it jumps to the fourth position. High blood sugar also jumped from 11th in 1990 to third in 2017.

"The world has seen several health success stories,"says Murray, explaining the major global shifts in causes of death. "Investments made in poor countries addressing prenatal care and water and sanitation problems clearly have made a significant difference in people's lives. Conversely, the combination of increasing metabolic risks and population aging will continue driving problematic trends in non-communicable diseases."

Other trends

The GBD also offers some alarmingly precise insights into trends we already knew were occurring, such as the striking figures on opioid use. Global deaths from opioid use increased from around 60,000 in 2007 to well over 100,000 in 2017. That's a global increase of over 75 percent in less than a decade.

Another growing cause of global mortality is deaths related to conflict and terrorism. These are two of the fastest growing causes of death worldwide, increasing by around 118 percent over the past decade.

Women continued to display greater life expectancy than men in the latest GBD. In almost every country surveyed women lived, on average, longer than men. However, the disturbing caveat is that women tend to live more of their later years in poor health.

The Lancet published an editorial accompanying the seven papers, describing the data from the 2017 GBD as "disturbing".

"Not only do the amalgamated global figures show a worrying slowdown in progress but the more granular data unearths exactly how patchy progress has been," the editorial states. "GBD 2017 is a reminder that, without vigilance and constant effort, progress can easily be reversed. GBD 2017 should be an electric shock, galvanizing national governments and international agencies not only to redouble their efforts to avoid the imminent loss of hard-won gains but also to adopt a fresh approach to growing threats."

You can dig through the massive trove of GBD 2017 data here at IHME, while the new studies are published in The Lancet.

Source: IHME