Marshall R, Paul L, McFadyen AK, Rafferty D, Wood L
Division of Nursing and Health Care, Faculty of Medicine, Glasgow University, UK; School of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow, UK
Until now, there has been a lack of fundamental research into the pain experienced in chronic fatigue syndrome (CFS). The aims of this study were to (1) investigate the pain experiences of people with CFS with a range of disability, and (2) identify specific pain characteristics of people with CFS.
Fifty people were recruited, including 10 people who were severely disabled by CFS (25% Group). Participants completed a structured interview and a series of pain assessments about their current pain, which included the McGill Pain Questionnaire (MPQ), the Pain Anxiety Symptoms Scale (PASS), and visual analog scales.
Muscle pain was the most reported painful symptom (68 percent). The current pain intensity was 43.2 mm ± 20.8 mm measured on a visual analog scale. The MPQ pain rating index was 23.6 ± 10.8. The PASS total score was 37.9 ± 17.6. Thirty percent (N = 15) of participants reported the cervical spine the location of “most severe” pain, followed by the left and right scapular and right lumbar spine (N = 10 each, 20 percent each). Further analysis indicated that those people who were severely disabled by CFS also experienced significantly more pain (P<0.05).
The results of this study provide objective data to support anecdotal and clinical reports of pain in people with CFS. Pain in people with CFS should be accepted and treated as seriously as other conditions where pain is a significant symptom. Management strategies need to be tailored to the individual requirements of patients presenting with symptoms of both fatigue and pain.
This study was jointly funded by ME Research UK and Glasgow Caledonian University.
Comment by ME Research UK
Pain is a very common symptom in ME/CFS; it tends to be experienced in the muscles and/or joints, but it can often be widespread and changeable in location and intensity. In surveys, 79% of patients say that they had severe pain sometimes, much of the time, or all of the time, and between 84 and 94% of patients in formal research studies report some degree of muscle or joint pain.
Despite this, there is very little scientific information about the specific pain characteristics of ME/CFS patients: What kind of pain is it? Where is it localised? What strength is it? To explore such questions, ME Research UK provided part-funding for a PhD studentship, under the supervision of Prof. Lorna Paul and Dr Les Wood, at Glasgow Caledonian University. The first scientific paper from this work has just been published in the Journal of Musculoskeletal Pain.
For the investigation, 50 people with ME/CFS and painful symptoms were recruited from support groups across Scotland; all had previously been diagnosed by a consultant or general practitioner, and all met the CDC-1994 and Canadian Guideline symptom criteria. No participants had any psychiatric illness or any other serious conditions such as cancer, rheumatoid arthritis or multiple sclerosis (which would have affected their experience of pain).
The investigators visited the patients in their own homes to conduct their interviews, which allowed the participation of those who were so severely affected that they would not have been able to make a trip to the hospital. This was particularly important in this study since the researchers wanted to ensure that the findings represented the full spectrum of ME/CFS. Between 10 and 25% of ME/CFS sufferers fall into the “severe” category, so 10 of the 50 patients interviewed by Dr Paul’s team were either housebound or bedbound and had been recruited via the national charity, the 25% ME Group which caters for severely ill patients.
Overall, the 50 patients had been ill for an average of 12.6 years (range 1.3 to 27.4 years), and only one was working full time, and two part-time. A number of tools and questionnaires were used to evaluate participants’ experience of pain, and these consisted of a visual analogue scale, the Margolis Body Chart, the McGill Pain Questionnaire, the Pain Anxiety Symptoms Scale-20 and the Medical Outcome Survey Short Form-36 (see the section below for more detailed descriptions of each of these).
The results revealed that pain is indeed an important symptom of patients with ME/CFS. The most common painful symptom was muscle pain, which was reported by over two thirds of patients. The average intensity of pain at the time of the interview was reported to be around 43 out of a maximum of 100 mm on the visual analogue scale (see below), while the average intensity over the previous 24 hours was higher at around 58 mm. The investigators suggest that this latter value may be a more accurate reflection of patients’ experiences, particularly if pain fluctuates. Significantly, ME/CFS patients reported worse pain than did patients with rheumatoid arthritis or multiple sclerosis in previous studies, both conditions in which pain is recognised as a major symptom.
Patients used words such as “throbbing”, “aching”, “tender”, “gnawing” and “burning” to describe the pain they experienced, while those with more severe illness also used “exhausting” and “nagging”. In fact, only the severe patients chose the word “gruelling” while none chose the less emotive words “tight” or “annoying” — indicating a more severe quality of pain, as well as intensity, in the most severely affected group. These descriptions may give clues as to the mechanisms causing pain in ME/CFS; in particular, “burning” pain is often associated with neuropathic conditions in which the nerves have been damaged. Also, they may help in assessing any change in the quality of pain over time, such as after treatment, as Dr Paul’s group suggests. Despite this burden of pain, most participants described their mood as generally positive, although those with more intense pain tended to describe a lower mood.
The most common locations of pain were the cervical spine (66%), the anterior thighs (44 to 46%), the lumbar spine (42%) and the posterior calves (38%), and most participants had pain in more than one location. Nearly a third of patients said they experienced their most severe pain in the area of the cervical spine/upper trapezius, while 20% reported the scapular/upper thoracic area and another 20% reported the right lumbar spine as the most painful regions. Twenty-eight participants said they experienced the worst pain in the morning, while it was the afternoon for four individuals, the evening for ten and the night for eight.
The results of the Pain Anxiety Symptoms questionnaire suggest that the study participants were not overly anxious or fearful because of their pain, although the most severely affected were more susceptible. When considering quality of life, Dr Paul’s findings were similar to those of Dr Gwen Kennedy’s study from 2004 (published in the Annals of Epidemiology). Patients tended to have reduced physical functioning and vitality (but not emotional or mental health), and again this was more pronounced in those with more severe illness.
This is the first major study to document and categorise the pain experienced by people with ME/CFS, and to provide sound, objective, scientific support to their anecdotal and clinical reports of painful symptoms. As the authors say, “
This study has emphasized that the problem of chronic pain in CFS needs to be treated as seriously as the pain experienced in other conditions such as rheumatoid arthritis and MS.”
Tools used to assess patients
Visual analogue scale
Participants are asked to indicate their current pain intensity on a visual scale from 0 mm, representing “no pain”, to 100 mm, representing “most pain ever experienced”.
Margolis Body Chart
Participants use a diagram of the human body to indicate the areas in which they experience the most pain. This is then matched to a chart which divides the body into 45 sections, in order to identify the locations of most pain.
McGill Pain Questionnaire
Participants are asked to describe their pain using words from a standard list of 78, grouped into 20 subcategories. Numerical values are assigned to each word, and a Pain Rating Index is calculated as the total of the values for each word chosen. This provides a measurement of the pain itself (sensory component), as well as unpleasant feelings and emotions (affective component), and how it is judged by the sufferer (evaluative component).
Pain Anxiety Symptoms Scale-20
Participants are asked to score their experience of 20 psychological aspects of pain, such as anxiety, fearful thinking, feelings of wanting to escape or avoid a situation, and physiological responses. Each item is scored from 0 (never) to 5 (always), and the total is calculated out of a maximum of 100.
Medical Outcome Survey Short Form-36
A questionnaire consisting of thirty-six questions examining physical functioning, physical role, bodily pain, general health, vitality, social functioning, emotional role and mental health. The participant’s answers to each question are translated into a total score from 0, representing poor health, to 100, representing good health.
This essay is an extract from our article (pdf 941 KB) in the Autumn 2010 issue of Breakthrough.