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This fact sheet will be updated in 2019.
What is chronic pain?
Chronic pain is defined as pain lasting six months or more (1). It is common to distinguish between three main types:
- Nociceptive pain, caused by tissue damage, e.g. rheumatic diseases with joint damage.
- Neuropathic pain, caused by dysfunction of the nervous system, e.g. sciatica.
- Idiopathic pain, of unknown origin, e.g. non-specific back and neck pain.
The most common chronic pain conditions occur in the muscles and skeleton (2). Most often this is non-specific back and neck pain and other pain of unknown origin. Muscular and skeletal pain can also be caused by pressure on a nerve (e.g. sciatica), and various rheumatic disorders.
Other chronic pain conditions include headaches, various abdominal, pains from injuries and surgery, pain associated with cardiovascular disease and with neurological disorders.
Although the causes of chronic pain can be complex and very different, there are similarities when it comes to risk factors, symptoms, consequences and treatment. Therefore, chronic pain is often considered to be a distinct disorder, regardless of the cause (3).
Chronic pain in children and adolescents
The incidence of chronic pain in children and adolescents is poorly mapped in Norway, but the consumption of analgesics and figures from other countries suggest that chronic pain is also common in adolescence (8). In the Health Interview Survey of 2005, parents reported that 6 per cent of children aged 6-10 years and 12 per cent of adolescents aged 11-15 years had chronic pain symptoms.
A study of 12-15 year olds in South and North Trøndelag shows that 17 per cent suffered regularly from headaches, abdominal pain, back pain or pain in arms / legs (9). Consumption of analgesic drugs among Norwegian 15-16 year olds is high and has risen considerably since 2001 (10).
Chronic pain in adults
An estimated 25-30 per cent of adults in Norway suffer from chronic pain (Table 1).
Most chronic pain conditions become more common with increasing age. The increase with age is probably mainly due to increased morbidity, but there is also evidence that the mechanisms that suppress pain (e.g, endorphins) are less effective in the elderly, and that this may contribute to increased pain sensitivity (11).
Some studies show a levelling off or slight decline in pain symptoms after 60 years of age, but this may be due to lack of data for people in nursing homes and hospitals.
Chronic pain is inadequately mapped in Norway. In addition, the prevelance of many diseases that lead to chronic pain is unknown. As a result, there is insufficient basis to conclude whether prevalence has changed over time.
Chronic pain in women and men
Women are affected by chronic pain to a much larger extent than men and also report stronger pain than men with similar diseases (12). This gender difference arises only after puberty. It is thought that sex hormones may partly explain these gender difference (12). Gender differences in pain contribute significantly to the higher rates of sick-leave and disability among women.
Social and ethnic differences
|Pain in Europe (4)||30 per cent|
|Rustøen et al. (5)||24 per cent|
|Living Conditions Survey 2005 (6)|| 29 percent
Chronic pain is more common among people with low income and education, but it is unknown whether this is due to work load or more general socio-economic factors.
From the USA it is known that some ethnic minorities have increased pain sensitivity and experience chronic pain as more intense and debilitating than the general population (13). The Oslo Health Study (2000-2002) showed that the prevalence of muscular and skeletal disorders is higher among people born outside Norway (43 per cent) than those born in Norway (33 per cent). Immigrants also report that pain affects their ability to work to a greater extent than ethnic Norwegians. Possible explanations may be socio-economic and cultural differences, differences in work load and genetic differences.
Chronic pain and mental health
Chronic pain increases the risk of impaired mental health and the risk of dependence on addictive drugs. Chronic pain patients have a two to four times higher incidence of anxiety and depression and twice the incidence of suicide as the general population (30, 31). Sleep disorders are also common.
Causes of disability and sick leave
Chronic pain is the most common cause of long term sick leave and disability in Norway today. Muscular and skeletal disorders were the main diagnosis in 41 per cent of sick leave days that were covered by social security in the period January-June 2009. Among disability pension recipients (2007), muscular and skeletal disorders were the cause in 32 per cent of cases. The statistics do not include other types of pain conditions and the impact of chronic pain on work participation is therefore likely to be greater than these figures suggest. Analysis of data from the Health Interview Survey of 2005 (6) shows that chronic pain explained 54 per cent of disability cases.
Risk factors and protective factors
Genetic factors play a role in the development of chronic pain conditions and pain sensitivity (15, 16). Twin studies indicate that about half the risk of developing chronic pain can be attributed to genetic factors. Heritability estimates range from 30 to 70 per cent for most pain conditions (14).
Low back pain is more common in occupations involving heavy physical labour. Pain in the upper back, shoulders and arms are common among people who have lighter and more sedentary work such as medical secretaries (17). Although it is conceivable that these findings are related to selective recruitment to specific professions, they suggest that occupational stress is important.
- Pain sensitivity
Chronic pain patients have increased pain sensitivity compared with the general population. In people with various conditions, including fibromyalgia, there are documented changes in the mechanisms that regulate pain in the spinal cord and brain (18). It is uncertain whether increased pain sensitivity is a cause or a consequence of chronic pain.
- Psychological factors
Psychological factors have some significance for pain. Surgical patients with high pre-operative anxiety and depression, experience greater pain after surgery than patients with low pre-operative anxiety and depression (19). It is likely that anxiety and depression also give an increased risk of developing chronic pain (20).
The interaction between pain and mental health is complex. Chronic pain and psychiatric disorders are most likely mutually reinforcing (21), but mental health issues are unlikely to be the initial cause of pain.
- Side effects of surgery
Chronic pain may in some cases be a result of treatment, in particular surgical treatment.. Depending on the type of surgery, 10-50 per cent experience chronic pain after surgery. The pain is severe in 2-10 per cent of these (22). In a Norwegian study of young, healthy women who had cosmetic breast surgery, 13 per cent reported spontaneous pain and 20 per cent reported pain when touched one year after surgery (23).
- Protective factors and prevention
Physical activity seems to be protective against the development of chronic pain by activating pain inhibiting mechanisms. Physical activity is also an important part of pain management. Reducing heavy and / or repetitive physical strain at work may help reduce the incidence of chronic pain.
Beyond this, preventive measures focus primarily on the individual problem, e.g. improved surgical techniques that minimise nerve damage prevent chronic pain after surgery. Prevention of osteoporosis can avoid compression fractures in the back which often cause significant chronic pain.
Pain is probably the most common reason for patients to seek health care (26). A Swedish study found that 28 per cent of patients in general practice had one or more medically-defined pain conditions (27). Corresponding figures are found in Denmark (28), where it has also been shown that chronic pain patients had four to five times more in-patient days in hospital than the general population (29). Corresponding figures for Norwegian conditions are unavailable.
The Norwegian Directorate of Health has developed national guidelines for the right to prioritised health care for pain conditions (32). The Ministry of Health and Care Services has also ordered the regional health authorities to improve services for patients with chronic pain in collaboration with the municipal health service. Internationally, a multi-disciplinary approach to pain management is recommended.
The most common method of chronic pain management is with analgesic drugs (painkillers). Both opioids (morphine-like agents) and paracetamol /acetaminophen (pain relief/anti-pyretic) and NSAIDs (non-steroidal anti-inflammatory drugs) are used.
Around 200 of 1000 men and 270 of 1000 women under 80 years were given analgesic drugs on prescription in 2015 (figure 1). This amounted to around 1 million people. Of these, about 90 of 1000 men (nine per cent) and 110 of 1000 women (11 per cent) under 80 years were dispensed an opioid, a total of 498 000 people. Most people use opioids for a short time, but approximately 13 000 people received more than 400 defined daily doses per year in the period 2004-2007 (25).
In addition, sales statistics for 2008 show that over-the-counter analgesic drugs amounting to 70 analgesic tablets per person per year were sold.
Figure 1. The proportion of men who and women who received analgesics on prescription 2005-2015. The graph shows the number of users per 1000; at the top, total analgesics used. Figure in English Source: Norwegian Prescription Database.
Figure 2. The use of different analgesics in 2015. Number of users per 1000 inhabitants; men (blue) and women (yellow). At the top, total analgesics used. Below, by subgroup; anti-inflammatories, opioids, other analgesics, anti-migraine medication Figure in English Source: Norwegian Prescription Database.
Many analgesics are effective for a short time period, but carry a risk of habituation and dependency with prolonged use. This is particularly the case for opioids. Other analgesics can also cause side effects when used over time. NSAIDs can cause bleeding / stomach ulcers. Both NSAIDs and weaker analgesics can cause medication-induced headache.
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