Understanding Chronic Pain

The International Association for the Study of Pain (IASP; 1994) defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage”. It can be further divided into two subcategories which are acute pain and chronic pain. Acute pain is a short-lived normal sensation that alerts individuals of potential injury while chronic pain is any pain that lasts more than twelve weeks and can be mild or intense. Chronic pain has a distinct pathology, causing changes throughout the nervous system that often worsen over time. It has significant psychological and cognitive correlations and can constitute a serious, separate disease entity (Institute of Medicine, 2011, p.3). Some forms of chronic pain, such as pain resulting from fibromyalgia, may be controlled or treated with therapies; however chronic pain, such as neuropathic pain or migraine, may be far more challenging to diagnose and treat.

Chronic pain exists in almost every age group. The pattern of chronic pain can be episodic or continual, and the intensity of chronic pain can be minor and merely inconvenient, or excruciating and totally incapacitating which can cause serious impairment in sufferers’ daily life. Chronic pain was also found to have associations with other comorbid issues such as fatigue, depression and post-traumatic stress disorder (PTSD). Additionally, individuals who suffer from chronic pain are at greater risk for suicide as compared to pain-free community controls (Fishbain, Bruns, Disorbio, & Lewis, 2009).

Various studies have been done to investigate different aspects of chronic pain. This review will briefly cover the prevalence of chronic idiopathic pain (i.e., non-cancer related pain), its impacts on sufferers’ quality of life and their emotional status, followed by a view of causes and treatments of chronic pain, and also discuss several pros and cons of some of the studies being covered.

Method

In the studies reviewed, three main instruments were used, i.e., numerical rating scale (NRS), verbal descriptor scale (VBS) and McGill pain questionnaire (MPQ). NRS is a form given to suffers to rate their pain intensity on a scale of 0 to 10 with 0 being “no pain” and 10 indicating “excruciating pain”. VBS is a measurement in which sufferers are asked questions and respond verbally choosing from such terms as “none”, “slight”, “mild”, “moderate”, and “severe”. MPQ measures several dimensions of the pain experience such as location of pain, pattern of pain over time, pain intensity and etc. (Melzack, 1975). Methods adopted by other studies include pain diary, which is a record of pain that participants were requested to keep daily (usually for three weeks), and computer-assisted telephone-interview-surveys.

Prevalence of Chronic Pain

The prevalence of chronic pain in different age groups has shown an increase in trends in the world. In two studies conducted in Europe and Canada with larger sample sizes (n1=46,394, n2=69,365) and with a mean age of 45 years, the prevalence of chronic pain (NRS ³ 5) was found to be around sixteen percent (Breivik, Collett, Ventafridda, Cohen, & Gallacher, 2006; Rashiq & Dick, 2009). Both studies and another study (Boulanger, Clark, Squire, Cui & Horbay, 2007) which was also conducted in Canada found that chronic pain was reported more often in women. Additionally, twenty-five percent of 5,423 participants aged 4 to 18 years old were found to be suffering from chronic pain for more than 3 months and chronic pain reported by girls was significantly higher than boys (Perquina, Hazebroek-Kmpschreurb, Hunfeldc, Bohnena, Suijlekom-Smitd, Passchierc, & Woudena, 2000). All four studies found that the prevalence of chronic pain increased with age.

Impacts of Chronic Pain on Activities of Daily Life

Chronic pain was found to be disruptive to sufferer’s daily activities. According to Breivik et al., many of the sufferers were less able or no longer able to take part in various activities such as exercising, walking, attending social activities and maintaining independent lifestyles. Most of them claimed that activities during the day had drastically worsened the pain. Additionally, almost one in five sufferers had lost his/her job because of the pain (2006). A study of chronic pain in 128 adolescences found that social functioning (such as interaction with siblings and peers) and functional status (such as ability to carry out day-to-day tasks) of adolescents were also greatly affected by chronic pain (Hunfeld, Perquin, Duivenvoorden, Hazebroek-Kampschreur, Passchier, Suijlekom-Smit, & Wouden, 2001). Children and adolescents with chronic pain frequently report disturbances in sleeping and eating habits, reduced participation in social activities or hobbies, and school absence (Roth-Isigkeit, Thyen, Stoven, Schwarzenberger, & Schmucker, 2005).

Furthermore, many children with chronic pain had significant problems with comorbid fatigue, an overwhelming sense of tiredness, lack of energy, and feeling of exhaustion (Krupp & Pollina,1996), which caused impairments in their attention and memory (Gold, Mahrer, Yee, & Palermo, 2009). Additionally, chronic pain was found to have significant impact on families where parents with children who reported having chronic pain tended to be more controlling and protective (Hunfeld et al., 2001).

Impacts of Chronic Pain on Emotional Status and Psychological Functioning

Chronic pain was also found to have huge impacts on sufferers’ emotional status and psychological functioning. It was found twenty percent of sufferers had been diagnosed with depression due to their pain (Breivik et al., 2006). Findings from 85,088 participants from 17 countries indicated that those with back or neck pain are two to three times more likely to have had panic disorder (PD), agoraphobia, or social anxiety disorder (SAD), and generalized anxiety disorder (GAD) or PTSD (Demyttenaere, Bruffaerts, & Lee, 2007). Furthermore, data showed that women with fibromyalgia were four to five times more likely to have had a lifetime diagnosis of obsessive-compulsive disorder (OCD), PTSD, or GAD than those without (Raphael, Janal, Nayak, Schwartz, & Gallagher, 2006). Anxiety disorders were also found in most chronic pain sufferers (Fumundson & Katz, 2009). According to Hunfeld et al. (2001), it was found that children reported with more chronic pain were associated with poorer psychological functioning. These children would tend to have more association with negative emotions such as stress and depression and less association with positive emotions such as optimism, humor and harmony. Additionally, chronic pain was negatively associated with alcohol consumption and cigarette smoking (Rashiq & Dick, 2009). It was also associated with a specific cognitive deficit, which could impact everyday behavior especially in risky, emotion laden, situations (Apkariana, Sosaa, Kraussb, Thomasc, Fredricksond, Levye, Hardenf, & Chialvoa, 2004).

Causes and Treatment

Chronic pain can be initiated by many causes. According to sufferers’ comments, low back pain, arthritis (especially osteoarthritis), headache (migraine), multiple sclerosis, fibromyalgia, shingles, nerve damage (neuropathy) and abdominal pain are common factors that cause chronic pain (Dangel, 2005; Breivik et al., 2006; Bouhassira, Michel, Attal, Laurent, & Touboul, 2008). Generally, two ways of controlling chronic pain are drug-used treatments and nondrug treatments. A wide variety of medicines have been shown to help ease pain, such as pain relievers, antidepressants, anticonvulsants, and opioids. Patients should be wary of using opioids as they have the potential to be addictive. Additionally, nondrug treatments include acupuncture, massage, mediation, biofeedback, exercise as well as physical and psychological therapies.

Discussion

Pain is a very personal and subjective experience which makes it hard to be measured. Both the clinician and the pain researcher face three distinct challenges when attempting to measure pain (Flaherty, 1996). First, researcher must understand that the pain experience described by the sufferers must be viewed from the sufferers’ perspective instead of his or her own unique perceptions and responses to the pain experience. Pain tolerance and behavioral expression of pain differ from gender, age, cultural norms as well as expectations (Bates, 1987; Zatzick & Dimsdale, 1990). For example, women of two subcultures on the same island appear to experience labor pain quite differently (Morse & Park, 1988). Therefore, in order to obtain the most accurate information, researchers have to be cautious not to filter participants’ description of pain experience with their own judgements.

Next, sufferers’ perception and response of pain can be influenced by both clinical factors (such as any prior experience with the therapy employed in its management) and personal factors (such as sufferer’s education background, gender and ethnic background). Research conducted by Breivik et al. did well in considering this aspect as the researchers had further categorized participants into many categories including gender, ethnic background, nationality, and prior exposure to prescribed or non-prescribed medicine. By doing so, the findings obtained would have less bias and would be more generalizable to a larger population.

Finally, there are only a limited number of pain measurement instruments accessible that are computable, reliable, and valid, such as the methods aforementioned. Although researchers have selected the most suitable method to conduct the studies, disadvantages were still found in each study. For example, telephone-interview-surveys might have some flaws as older people and patients ill in bed are less likely to pick up the phone which might cause the results to be swayed towards younger generations. Additionally, women are more willing to accept telephone interview than man (Moulin, Clark, Speechley, Morley-Forster, 2002) which could affect the results of the study. For examples, two studies conducted by Boulanger et al. and Breivik et al. respectively used telephone-interview-surveys, both studies had more female participants and unsurprisingly, found higher prevalence of chronic pain in female. Therefore, in order to reduce such limitations, researchers should consider using multiple methods in conducting future studies.

Conclusion

In conclusion, the prevalence of chronic pain was found to be sixteen percent in adulthood and nearly twenty percent of children and adolescents. It was reported more in females. Chronic pain was found to have huge impacts on both sufferers’ quality of life and emotional status. Additionally, sufferers who reported pain in different body locations were more vulnerable to different disorders such as OCD, PTSD and GAD. According to participants’ comments, low back pain, arthritis (especially osteoarthritis), headache (migraine), multiple sclerosis, fibromyalgia, shingles, nerve damage (neuropathy) and abdominal pain are common causes of chronic pain. Treatments of chronic pain include drug-used treatments (such as pain reliever and antidepressants) and nondrug treatment (such as exercise, mediation and physical therapy).