How big a problem is chronic pain?

Chronic pain has been linked to numerous physical and mental conditions, and contributes to high health care costs and lost productivity. (1)

Chronic pain, one of the most common reasons adults seek medical care. (2)

It is estimated that between at least 20% and in some sub-groups 40% of people are experiencing chronic pain at any given time.

This is linked to:
 - restrictions in mobility and daily activities (3,4),
 - dependence on opioids (5),
 - anxiety and depression (3),
 - and poor perceived health or reduced quality of life 

Chronic pain is a huge problem. In the USA alone chronic pain contributes to an estimated $560 billion each year in direct medical costs, lost productivity, and disability programs.

Despite an abundance of pain killers on the market, and a wide variety of physical therapies, chronic pain continues to be the experience for hundreds of millions of people. Plus, it's incidence is on the rise. (6)

Is there...