Obesity-Related Deaths Hit New High Worldwide

More people worldwide are dying from obesity-related causes than ever before, a new study indicates.

Between 1990 and 2015, the global rate of death related to high body mass index (BMI) increased by 28.3%, from 41.9 to 53.7 deaths per 100,000 people, and the rate of BMI-related disability-adjusted life-years increased by 35.8%, from 1200 to 1630 per 100,000 people, Christopher JL Murray, MD, director of the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, Seattle, and colleagues in the Global Burden of Disease (GBD) program report in an article published online today in the New England Journal of Medicine.

In a systematic evaluation of the health effects of high BMI, "we found that excess body weight accounted for about 4 million deaths and 120 million disability-adjusted life-years worldwide in 2015," the authors write. "Nearly 70% of the deaths that were related to high BMI were due to cardiovascular disease, and more than 60% of those deaths occurred among obese persons."

The increasing burden of disease parallels the substantial and widespread rise in global obesity rates over the past 3 decades and suggests that obesity continues to be a major public-health problem in both the developed and the developing world, Dr Murray and colleagues stress.

Increases in Obesity Seen Across the Board, Often Greatest in Children

For the current report, the international consortium of GBD researchers analyzed trends in the global prevalence of overweight and obesity between 1980 and 2015 among children and adults, and they evaluated patterns of BMI-associated deaths and disability-adjusted life-years according to age and sex in 195 countries from 1990 through 2015.

In 2015, an estimated 107.7 million children and 603.7 million adults worldwide met the criteria for obesity, with an overall obesity prevalence of 5% and 12%, respectively, for children and adults. The prevalence among adults was higher in women than men, and the highest rate of increase in obesity between 1980 and 2015 was seen in early adulthood.

Sociodemographic factors appear to be related to obesity rates. "In general, the prevalence of obesity among both women and men increased with the increase in the [sociodemographic index (SDI)] across all age groups," the authors write. Similarly, among children, obesity prevalence was greater in countries with higher SDI levels; however, between 1980 and 2015, the prevalence of obesity in children in low-SDI countries increased significantly, by 20%.

The increased prevalence of obesity across levels of development "indicates that the problem is not simply a function of income or wealth," the authors write. "Increased availability, accessibility, and affordability of energy-dense foods, along with intense marketing of such foods, could explain excess energy intake and weight gain among different populations."

Obesity prevalence among children and adults increased consistently over the 35-year period in nearly all of the countries, and it more than doubled in 73 countries.

And although the prevalence of childhood obesity is lower than the prevalence of adult obesity, "the rate of increase in childhood obesity in many countries has been greater than the rate of increase in adult obesity," the authors note.

Egypt Has Highest Rate of Obese Adults; for Kids, it's the US

Examining the 20 most populous countries specifically, between 1980 and 2015, the age-standardized prevalence of obesity increased by a factor of two or more in 13 of the 20 countries, and the highest levels of age-standardized adult obesity and childhood obesity, respectively, were seen in Egypt (35.3%) and in the United States (12.7%), the authors report.

In 2015, the United States and China had the highest number of obese adults, and China and India had the highest number of obese children.

The burden-of-disease analyses showed that cardiovascular disease accounted for 2.7 million of the 4.0 million obesity-associated deaths and 66.3 million of the 120 million obesity-associated disability-adjusted life-years.

"Globally, 41% of BMI-related deaths and 34% of BMI-related disability-adjusted life-years were due to cardiovascular disease among obese persons," the researchers say.

Diabetes was the second leading cause of BMI-related mortality in 2015, and chronic kidney disease was the second leading cause of BMI-related disability-adjusted life-years.

Despite the nearly 30% relative increase in the global rate of death related to high BMI from 1990 through 2015, there was no significant change in age-standardized rates of death during this period, nor was there a significant change in age-standardized rates of disability-adjusted life-years, the authors report.

This is likely because "globally, the increases in BMI-related deaths and disability-adjusted life-years due to population growth, population aging, and increasing risk exposure were partially offset by reductions in underlying rates of death and disability-adjusted life-years," the authors say.

The rate of increase of obesity prevalence is greater than that of disease burden.

"This difference was driven mainly by the decline in risk-related mortality, particularly for cardiovascular disease; factors such as improved treatment or changes in other risks have resulted in decreases in the rate of cardiovascular disease despite increases in BMI."

More Time Spent With Damaging Coexisting Illnesses

The fact that population-level age-adjusted rates of death and disability have not increased at the same rate as high BMI prevalence is "encouraging" in that it indicates better care and risk-factor management.

But it also introduces a new burden, Edward W Gregg, PhD, of the division of diabetes translation at the Centers for Disease Control and Prevention and Jonathan E Shaw, MD, of the division of clinical and population health at the Baker Heart and Diabetes Institute in Melbourne, Australia, write in an accompanying editorial.

"The mix of increased prevalence and decreased mortality leads to more years spent with obesity and more time for the damaging coexisting illnesses, such as type 2 diabetes and chronic kidney disease, to develop."

Of particular concern to the editorialists is the near-tripling of obesity rates seen in children and young adults in developing, middle-income countries, such as China, Brazil, and Indonesia.

"An early onset of obesity is likely to translate into a high cumulative incidence of type 2 diabetes, hypertension, and chronic kidney disease," they write. "An increased incidence of diabetes among children may shift a proportionately greater load of morbidity into middle age and spread the burden of chronic disease more fully across the entire age distribution, even as populations continue to age."

Referring to the study findings as "an impressive and essential effort to provide policy makers with both global and country-specific estimates," the editorialists caution that some of the modeling assumptions may obscure the influence that racial, ethnic, and regional variations might have on obesity-related outcome risks.

"Gaps in available data have forced the GBD researches to make the best of a checkerboard of periodic and suboptimal data to provide a global picture," say Drs Gregg and Shaw.

"However, the magnitude of obesity-related morbidity and the demands for effective public-health decision-making point to the need for improvements in at least three types of data: efficient, continuous surveillance systems to assess risk factors, prevalence, care, and outcomes of chronic diseases; cohorts in more diverse populations to capture variation in progression to outcomes; and platforms for natural experimental studies to determine which of the interventions are working locally and why."

This study was funded by the Bill and Melinda Gates Foundation. The study authors have no relevant financial relationships. Dr Shaw reports receiving personal fees from Novo Nordisk.

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N Engl J Med. Published online June 12, 2017. Article, Editorial

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