By Pat Anson, Editor

Lower back pain remains the world's leading cause of disability, according to an extensive new study of health data that also warns that the number of people living in poor health is set to rise rapidly over coming decades.

Using a statistical analysis known as "years lived with disability" (YLD),  the Global Burden of Disease Study ranks lower back pain as the leading cause of disability worldwide, followed by major depression.  

Low back pain was the leading cause of YLDs in 86 countries and the second or third leading cause in 67 countries. It also caused more health loss than diabetes, chronic obstructive pulmonary disease, and asthma combined.

Several other painful conditions also ranked high, including neck pain (#4), migraine (#7),  musculoskeletal disorders (#10), osteoarthritis (#13) and medication overuse headache (#18).

The study, which is published online in The Lancet, is the first to examine the extent, pattern, and trends in disabilities worldwide. An international consortium of researchers led by the Institute for Health Metrics and Evaluation (IHME) at the University of Washington studied 301 diseases and injuries in 188 countries.

They found that while people around the world are living longer, they are spending more time in ill health as rates of diseases and injuries decline more slowly than death rates.

Just one in 20 people worldwide had no health problems in 2013, with a third of the world’s population -- 2.3 billion people -- experiencing more than five ailments. Of those, 81% were younger than 65 years old.

The disease burdens for low back pain and depression both increased more than 50% since 1990. There was also a startling increase in disability caused by diabetes (up 136%), Alzheimer’s disease (up 92%), medication overuse headache (up 120%), and osteoarthritis (up 75%).

"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."

Between 1990 and 2013, YLDs increased from 537.6 million to 764.8 million for both sexes. The leading causes of YLD remained largely stable during this period, but they took an increased toll on health due to population growth and aging.

Musculoskeletal disorders, combined with fractures and soft tissue injuries, accounted for one-fifth of YLDs globally in 2013, ranging from a low of 11% for Mali's population to a high of 30% in South Korea.

"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."

Leading Causes of YLDs in 2013:

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

“Large, preventable causes of health loss, particularly serious musculoskeletal disorders and mental and behavioral disorders, have not received the attention that they deserve. Addressing these issues will require a shift in health priorities around the world, not just to keep people alive into old age, but also to keep them healthy,” said Vos.

This study was funded by the Bill & Melinda Gates Foundation.