As death rates drop, nonfatal diseases and injuries take a bigger toll on health globally

Using a measurement known as years lived with disability, or YLDs, researchers from around the world quantified the impact of health problems that impair mobility, hearing, or vision, or cause pain in some way but aren't fatal. In 2013, low back pain and major depressive disorder were among the 10 leading causes of YLDs in every country. Other leading causes globally included neck pain, anxiety disorders, migraine headaches, and diabetes. The leading causes of years lived with disability have remained largely the same during this period, but they are taking an increased toll on health due to population growth and aging.

YLDs per person increased in 139 of 188 countries between 1990 and 2013, meaning that more people are spending more time in poor health. Musculoskeletal disorders, combined with fractures and soft tissue injuries, accounted for one-fifth of YLDs globally in 2013, ranging from 11% in Mali to 30% in South Korea. Mental and substance abuse disorders also caused 20% of YLDs globally, ranging from 15% in Germany to 37% in Qatar.

"Global, regional, and national incidence, prevalence, and years lived with disability for 301 acute and chronic diseases and injuries in 188 countries, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013" is the first study to examine the extent, pattern, and trends of nonfatal health loss across countries. Published in The Lancet on June 8, the study was conducted by an international consortium of researchers working on the Global Burden of Disease project and led by the Institute for Health Metrics and Evaluation (IHME) at the University of Washington.

"Many countries around the world have made great progress in addressing fatal diseases, but nonfatal illnesses pose the next major threat in terms of disease burden," said Professor Theo Vos of IHME, the study's lead author. "This need to meet the challenge of nonfatal diseases and injuries only becomes more urgent as the population increases and people live longer."

Between 1990 and 2013, YLDs increased globally from 537.6 million in 1990 to 764.8 million in 2013 for both sexes. Men and women around the world share the same leading causes of YLDs, with the exception of schizophrenia as a leading cause for men and other musculoskeletal disorders for women. Musculoskeletal disorders, mental and substance use disorders, neurological disorders, and chronic respiratory conditions were the main drivers of YLDs in 2013. The disease burdens of both low back pain and depression have increased more than 50% since 1990.

Researchers found that as people aged they experienced a greater number of ailments resulting from nonfatal diseases and injuries. Many people also suffered from multiple conditions at the same time. The number of people who suffered from 10 or more ailments increased by 52%. And it's not just the elderly who are affected. Although the impact of YLDs increases with age, of the 2.3 billion people who suffered from more than five ailments, 81% of them were younger than 65 years old.

A relatively small number of diseases have a massive impact, researchers found. Just two acute diseases -- affecting people for less than three months -- caused more than 20 billion new cases of disease globally in 2013: upper respiratory infections (18.8 billion) and diarrheal diseases (2.7 billion). And just eight causes of chronic diseases -- affecting people for three months or longer -- impacted more than 10% of the world's population. These included tension-type headaches and iron-deficiency anemia.

In 2013, war and conflict was a leading cause of YLDs in several countries as well, including El Salvador, Lebanon, Guatemala, Peru, and Syria. In three countries -- Cambodia, Nicaragua, and Rwanda -- war was the top cause of years lived with disability. Other notable causes of YLDs in different regions included falls (Central Europe), asthma (a top-10 cause in many Latin American countries), and opioid dependence (a top-five cause in several Middle Eastern countries). Nonfatal conditions are not yet becoming the dominant source of disease burden in sub-Saharan Africa as they are in other parts of the world, but their impact has grown since 1990.

"What ails you isn't necessarily what kills you," said IHME Director Dr. Christopher Murray. "As nonfatal illnesses and related ailments affect more people of all ages, countries must look closely at health policies and spending to target these conditions."

Leading causes of YLDs globally for both sexes in 2013

1. Low back pain
2. Major depressive disorder
3. Iron-deficiency anemia
4. Neck pain
5. Age-related and other hearing loss
6. Diabetes mellitus
7. Migraine
8. Chronic obstructive pulmonary disease
9. Anxiety disorders
10. Other musculoskeletal disorders

Leading causes of YLDs globally for men in 2013

1. Low back pain
2. Major depressive disorder
3. Age-related and other hearing loss
4. Iron-deficiency anemia
5. Diabetes mellitus
6. Neck pain
7. Chronic obstructive pulmonary disease
8. Migraine
9. Anxiety disorders
10. Schizophrenia

Leading causes of YLDs globally for women in 2013

1. Low back pain
2. Major depressive disorder
3. Iron-deficiency anemia
4. Neck pain
5. Migraine
6. Other musculoskeletal disorders
7. Anxiety disorders
8. Age-related and other hearing loss 9 Diabetes mellitus 10 Chronic obstructive pulmonary disease