Chronic Pain: Definition, Statistics and Causes

Chronic pain affects 29 percent of Australians, which means that at any given time nearly three out of ten people are suffering in some way (Stollznow Research for Pfizer Australia, 2010). When we add the emotional, physical, and financial challenges of those who care for them, the percentage of lives touched by chronic pain is much higher. In this article, we’ll define chronic pain, and look at some statistics (in both Australia and United States), as well as the causes behind this debilitating condition.


If you were to injure yourself or have an accident, at what stage would you deem that you had “chronic” pain? Some people define it as pain that goes on three to six months without letting up. One in five Australians believes that chronic pain is simply intense pain, yet the actual meaning of the term relates to duration, not quality. Some countries use the phrase “long-term” instead of “chronic” to differentiate it from intense, short-term pain (usually called “acute”). This is an important distinction to make, because the methods for managing long-term pain can be different to managing intense, short term pain (Pfizer Health Report, 2011).

Some definitions focus on sensations and emotions, defining pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage” (Merskey & Bogduk, 1994).

For the definition of chronic pain we can use the Chronic Pain Australia definition:

“Chronic pain is defined as pain that extends beyond the expected healing time of an injury, or can accompany chronic illnesses such as arthritis or lupus” (Pfizer Health Report, 2011; Stollznow Research for Pfizer Australia, 2010).

Snapshot statistics on pain

In the United States

Chronic pain has been said to be the most costly health problem in the United States, where estimated annual costs total around $100 billion. Some of the component facts that comprise that statistic are:

  • Low back pain. A significant health problem, the Center for Disease Control and Prevention in the U.S. says that 70 – 85 percent of all people have back pain at some time in their life, and it is the most frequent cause of activity limitation in those under 45.
  • Cancer pain. This pain affects most people in intermediate and advanced stages of cancer; about 1.4 million new cancer cases are diagnosed each year in the U.S.
  • Arthritis pain affects nearly 66 million Americans each year (Stanford Hospital and Clinics, 2009).

In Australia

  • A 2007 report by Access Economics estimates the total cost of chronic pain in this country at $34.3 billion, which equates to $10, 847 per person with chronic pain; this estimate is expected to increase over time. It breaks down to:
    • 34% ($11.7 billion) in lost productivity
    • 34% ($11.5 billion) attributed to the burden of disease.
    • 20% ($7 billion) of health system costs, including hospital and medical costs as well as pharmaceuticals, other professional services and residential aged care (Access Economics, 2007).

In addition

  • An estimated 8.7% of people with chronic pain said that their pain problem had involved claims for damages or a legal case (Access Economics, 2007).
  • Twenty percent of people with chronic pain receive worker’s compensation payments (Stollznow Research for Pfizer Australia, 2010).

Lost productivity is traditionally counted as days off work, and these total about 9.9 million from chronic pain in Australia. But increasingly employers are recognising that “presenteeism” – reduced productivity while at work – are impacting on the bottom line as well, accounting for $1.4 billion per year. Adding presenteeism to absenteeism, we get about 36.5 million lost workdays per year in Australia, costing employers $5.1 billion (Access Economics, 2007, p24).

When Chronic Pain Australia launched an online survey for those living with chronic pain, there were nearly 600 respondents (n =587). Of those, nearly 93 percent (n=543) were between the ages of 20 and 65, indicating a sample of the population which would normally be participating in the workforce. The geographic distribution showed that over 51 percent (n=300, or 51.1%) lived in either New South Wales or A.C.T., while less than 1 percent came from the Northern Territory and Tasmania (n=3 and n=2, respectively).

In terms of duration of pain, most of the respondents had had pain for over five years. Sixty seven percent (n=395) had had pain for five years or more, while 44 percent (n=260) had had pain for over 10 years. The frequency of pain was also rated by respondents, with “1” indicating that they rarely had pain and “10” indicating constant pain. For this scale, 97.4 percent (n=572) recorded their frequency at “5” or above, with 44 percent of respondents nominating a frequency of “10”. Thus, greater than 40 percent of respondents experienced constant pain (Nielsen, Copleston, & Wales, 2009).

Causes of chronic pain

Anyone can develop chronic pain, although it most commonly affects older adults and people with health conditions such as arthritis, cancer, back problems, multiple sclerosis, and diabetes (Pfizer Health Report, 2011). Two people can have identical injuries or conditions, but experience very different levels of pain. Medical science does not know why one person may be so susceptible to feeling pain, while another has a relatively high threshold for experiencing it. While the differences could be due to individual or cultural background, genetic science is giving increasingly strong indications that pain response may be affected by our genes (Medtronic, 2013).

Psychological causes of pain have been identified as untreated occurrence of:

  • Depression
  • Anxiety
  • Grief
  • Unexpressed anger
  • Emotional overwhelm (, 2013)

Chronic pain frequently sets the sufferer up for a complex set of physical and psycho-social changes that are at the heart of the chronic pain problem. These secondary changes add greatly to the person’s burden of pain. They include:

  • Immobility and consequent wasting of muscles and joints
  • Depression of the immune system (more on this below) and increased susceptibility to disease
  • Upset sleep
  • Appetite and nutrition issues
  • Dependence on medication
  • Over-dependence on family and other caregivers
  • Repeated and/or inappropriate use of health care services
  • Poor job performance, or inability to work at all
  • Withdrawal from friends and family
  • Anxiety and/or fear
  • Bitterness, frustration, depression, and even suicide (Medtronic, 2013).

Nearly half (47 percent) of chronic pain sufferers in Australia say that their pain is the result of a diagnosed condition, such as multiple sclerosis, cancer, or some inflammatory condition. An additional 40 percent say that their chronic pain has been the consequence of some event such as an operation or accident-related illness. But fully 13 percent of chronic pain sufferers have no identified medical reason for their pain (Stollznow Research for Pfizer Australia, 2010). With so many possible causes (including the list of secondary causes, above) the precise cause of pain can be difficult to pinpoint. Moreover, whatever the original cause, pain can persist because of stress, emotional problems, improper treatment, or ongoing abnormal pain signals in the body.

And possibly the worst news of all is that pain can occur without any previous injury, illness or known cause, and even when it occurs from known diseases or illnesses, chronic pain may carry on long after the disease has been controlled or cured (Medtronic, 2013, emphasis added). To understand chronic pain and help someone move beyond it, we must examine two bodily systems which greatly affect the experience of pain: the nervous system and the immune system.

Pain and Central Nervous System Sensitisation: Off-balance chemistry

The next time you get a client with ongoing pain – someone who is experiencing high levels of stress and emotion – you could look the person straight in the eye and say, “You are causing yourself pain with your thoughts and emotions. Stop it right now!” Hopefully you won’t do that, because it would normally be far from a psychologically validating intervention. However, you could, because you would be stating with some accuracy how thoughts, feelings, and movements all impact on the nervous system to affect chronic pain.

In a process called Central Nervous System Sensitisation, the nervous system receives chemicals produced by the body as we respond cognitively and affectively to events in or perceptions of our environment (both inner and outer). Some of the chemicals produced calm down the system, inhibiting the pain reaction, and others excite the system, stimulating the pain response. The pain experience is related to ascending and descending messages, and also those involving processing centralised in the spinal cord itself (Wales, 2012a).

Messages ascending to the brain: Messages ascend to the brain from the spinal cord about damage or threat in the tissues, and sometimes the nerves transmit messages to the brain about their health (called “neuropathic” or neurogenic” pain).

Pain centralised in the nervous system: Within the spinal cord, the central nervous system can become highly sensitive to stimuli coming both from within the body and outside of it. In this process – the Central Nervous System Sensitisation referred to above – the nervous system adapts, becoming like a high quality amplifier. The analogy with the pain experience is that of the princess in the fairy tale who could feel a pea placed under 20 mattresses. The person’s system becomes so aware of stimuli that even low-key events, not noticed by normal people (i.e., non-chronic pain sufferers), are perceived as painful.

Messages descending from the brain: Fibres coming down from the brain via the spinal cord involve the sympathetic nervous system (our emergency “fight or flight” response), and also the parasympathetic, endocrine, immune, and motor systems. These are bound up with, respectively: resting and digesting, hormone production, defence, and movement. The nerve fibres associated with each make a contribution to the pain experience.

Normally, the sympathetic and parasympathetic nervous systems work to find a balance with each other so that we can function optimally in response to our environment. That is, we want to have a way to let the brain know when nerves or other tissues have been damaged, so that the brain can try to sort out a repair job. And we also want the body to know when the brain has detected danger so that it can respond protectively or defensively (preparing us to fight or flee, or raising the level of defence in the immune system to keep out unwanted biological invaders, for instance).

The role of the sympathetic system: The sympathetic is the part of our system that allows us to respond to emergencies, by distributing the stress hormone adrenalin, and also other chemicals, such as the feel-good endorphins (which, in primitive man’s existence, helped him to keep fighting despite injuries). The adrenalin gives us a shot of turbo-charged oxygen, which activates the muscles, dilutes the pupils, and generally helps us to become “superhuman” in order to take care of the emergency. Think sympathetic system when you hear the miraculous tales of, say, a parent lifting an entire car off their child that has just been run over.

With long-term stress, however, the picture begins to look a bit different. The body cannot stay at a level of “red alert” forever, so if the situation causing stress does not go away and is not dealt with, then we produce another chemical: cortisol. Too much cortisol can be damaging to both brain and body. The person becomes sick (Wales, 2012a).

Descending fibres: the chemical transporters: The descending fibres coming from the brain transport chemicals to the spinal cord, just as other chemicals are coming up from the body. The chemicals mix, and if there are more stimulating chemicals than inhibitory ones, the person has relatively more pain; if it is the other way around, the person experiences relatively less pain (Wales, 2012a).

The nervous system’s role in the experience of chronic pain is thus crucial, but it is not the only player in the game. There is also impact from the immune system.

The workaholic immune system

Like the nervous system, the immune system is set up to protect us, responding to anything that it deems a threat. It works by releasing chemicals which attack “invaders”. The chemicals trigger inflammation (from the Latin word “inflammare”, meaning “to inflame”) (The Free Dictionary, 2013). An inflamed area will often feel hot and be swollen and reddened. The immune system then works in further ways to protect us. The chemicals responsible for the inflammation make the surrounding area much more sensitive (called “peripheral sensitisation”), which reduces a person’s desire to use or move the area, thus ensuring that the injured/sick part is allowed to rest and recuperate.

Similar to the nervous system chemicals released in the fight-or-flight response, the chemicals brought forward by the immune system are a great aid to healing in the short term, but when the inflammation becomes long-term, the immune system becomes overactive and hypersensitive, responding to many innocent substances as if they were threats. The resultant auto-immunity then makes people ill with diseases such as ulcerative colitis, rheumatoid arthritis, and asthma (Wales, 2012b).

Spinal cord immune system becoming active: Moreover, the immune system can contribute to the spinal sensitisation described above (Central Nervous System Sensitisation), so even if the inflamed area is a person’s big toe, she may have inflammation from that showing up in the spine, causing pain to spread and worsen more than would be expected for such a localised injury. The release of these chemicals into the spine causes fever, fatigue, sleepiness, malaise, loss of appetite, loss of libido, social withdrawal, irritability, and hyperalgesia (heightened sensitivity to everyday activities causing increased pain). This group of symptoms, called the sickness response, can be triggered by many stressors:

  • Physical stress, as when one pushes one’s body too hard, say by overdoing exercise
  • Long-term use of codeine or high-dose morphine (opioid tolerance and opioid-induced hypersensitivity can be partially explained by this)
  • Nervous system injuries and infections
  • Ongoing stress, such as being involved in a legal case or caring long-term for a chronically ill family member (Wales, 2012b).

The good news about chronic pain

The good news is short and (sometimes) sweet. There are a raft of treatments and techniques to help manage pain. As many of them involve training the mind of the sufferer to think differently, you can have a starring role in a chronic sufferer’s pain management plan.

This article was adapted from the MHA CPD course “Managing Chronic Pain”. The purpose of this course is to give you, a counsellor, psychologist, or psychotherapist, a basic understanding of chronic pain, and how to help manage it, whether your client is an individual suffering from it or a caregiver supporting someone who does.


  • Access Economics (2007). The high price of pain: The economic impact of persistent pain in Australia, November, 2007. Access Economics Pty., Ltd, for MBF Foundation in collaboration with University of Sydney Pain Management Research Institute.
  • (2013). Chronic Pain. Retrieved on 22 May, 2013, from: hyperlink.
  • Medtronic (2013). Improving life by easing chronic pain. Medtronic, Inc. Retrieved on 22 May, 2103, from: hyperlink.
  • Nielsen, A., Copleston, P., & Wales, C. (2009). Pain is not invisible project. Chronic Pain Australia.
  • Pfizer Health Report (2011). Australians living with chronic pain. Pfizer Health Report, 46, p 4.
  • Stollznow Research for Pfizer Australia (2010). Chronic pain. Stollznow Research for Pfizer Australia. Australia: Pfizer Australia Pty Ltd.
  • The Free Dictionary (2013) Inflame. The Free Dictionary. Farlex, Inc. Retrieved on 3 June, 2013, from: hyperlink.
  • Wales, C. (2012a). The nervous system. Chronic Pain Australia. Retrieved on 22 May, 2013, from: hyperlink.
  • Wales, C. (2012b) The immune system. Chronic Pain Australia. Retrieved on 22 May, 2013, from: hyperlink.