This article describes contemporary controversies regarding two categories of soft-tissue pain (STP) – chronic widespread pain and fibromyalgia syndrome. The tone is more editorial than review didactic. It draws upon history to explain current trends that project possible future implications. It begins with an orientation to classification of STP pain conditions and contrasts two ways to make the fibromyalgia diagnosis. Epidemiological data will be placed in perspective. The article ends with the voice of a non-physician patient advocate.
STP classification divides relevant painful conditions into three subgroups, depending on the extent of body involvement (localised, regional and generalised). Fibromyalgia syndrome, in the generalised STP category, is distinguished from other types of chronic widespread pain by virtue of its greater severity. During the past 20 years, the diagnosis of fibromyalgia was based on a research classification (1990 American College of Rheumatology Research Classification Criteria (1990 ACR RCC)) that requires a history of chronic widespread pain and the examination finding of widespread mechanical allodynia. A new approach (2010 American College of Rheumatology Fibromyalgia Diagnostic Criteria (2010 ACR FDC)), validated for clinical use, still requires a history of chronic widespread pain, but the examination is replaced by a historical assessment of co-morbid symptom severity. The populations identified by the two criteria are similar but not identical. Misuse of the new criteria could expand fibromyalgia from 2 to 10% of the general population. Avoidance of the term ‘fibromyalgia’ could return it to the obscurity from whence it came, leaving a much larger problem in its stead.
The purpose of this article is to look into the future and try to conceptualise the view with respect to generalised musculoskeletal pain syndromes. The problem is that “It’s tough to make predictions, especially about the future.” …Yogi Berra. On the other hand, it is reasonable to predict that “The future (will be) made of the same stuff as the present.”… Simone Weil. It would be nice to know who had the insight to offer the following truism: “The future lies before you, like paths of pure white snow. Be careful how you tread (on) it, for every step will show.”…Anonymous.
For better or worse, the author has made a number of historical steps in the fine white snow of one generalised musculoskeletal pain condition, currently known as the fibromyalgia syndrome (hereafter fibromyalgia, FMS). That being the area of the author’s greatest familiarity, it seems wise to consider the environment in which that condition currently lies and to point out trends that may define some aspects of its future. Be forewarned that this article leans as much on history and philosophy as it benefits from science or clairvoyance.
It may be instructive to first review where fibromyalgia fits in a classification of musculoskeletal pain disorders . Fibromyalgia is just one of over 200 conditions that can cause body pain and interfere with mechanical function. From the rheumatologist’s viewpoint, it is logical to divide these into two main categories representing the conditions that specifically typically involve the joints (arthritis) and those which do not (non-articular). The preferred term to describe the non-articular conditions is ‘soft-tissue pain (STP) disorders.’ The abbreviation, STP, can be used in clinical charts as a category within both the medical history and the examination. Table 1 provides a useful classification of STP conditions, with the three main subheadings being ‘Local’, ‘Regional’ and ‘Generalised’. Most of the local conditions involve a single anatomic structure and are believed to have resulted from repetitive mechanical injury to inadequately conditioned tissues. They were usually named anatomically (e.g., biceps tendinitis) and are identified by a typical history plus the exquisite tenderness elicited by palpation of the affected structure when it is symptomatic. The regional syndromes are limited in anatomic scope to a quadrant of the body as seen with the myofascial pain syndrome or to a body cavity with visceral pain referral syndromes. The generalised category of STP implies a systemic process, such as that of fibromyalgia, which affects the musculoskeletal system in a global manner.
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In 1975, when rheumatologist, Hugh Smythe and psychiatrist/sleep physiologist, Harvey Moldofsky, published their work on the relationship of pain to insomnia in the ‘fibrositis syndrome’ (later reclassified as ‘fibromyalgia syndrome’ in 1989) , there was already a small group of clinicians interested in that condition, but not many of them were publishing their work. Part of the problem was that existing journals exhibited very little enthusiasm for publishing articles about this ‘pseudo-condition’ It must also be admitted that some of the work at the time may have been lacking in competitive scientific rigour.
That situation changed substantially when the 1990 American College of Rheumatology Research Classification Criteria (1990 ACR RCC) for fibromyalgia were published to standardise the clinical characteristics of fibromyalgia patients included in research studies . Fig. 1 provides graphic curves to represent the numbers of Medline-referenced articles published during 12-month periods at 5-year intervals from 1970 to 2010. For example, in the calendar year 1975, there were 20 articles published about fibromyalgia. The pattern of trickling annual publications continued until about 1990 when the new 1990 ACR RCC made it possible for research studies around the globe to depend on validated criteria. Since then, the numbers of annual publications about fibromyalgia have increased substantially (see Fig. 1 ). In addition, the strength of the evidence has improved, as clinical description was supported by convincing data regarding epidemiology, natural history, pathogenesis, neurochemistry, responses to various treatment interventions and costs of care . The total number of Medline-referenced fibromyalgia-related publications between 1948 and 2010 is 5597. Averaged over the past 62 years, this would represent nearly 90 publications annually. This is not an astounding number, but at a rate of nearly two per week, it is enough so that a busy professional would have difficulty finding every publication and digesting every nuance.
By contrast, the total number of Medline references for the regional soft-tissue pain condition called ‘myofascial pain syndrome’ was only 1073 during the same period of time. That condition experienced nearly linear growth in interest over the years but did not exhibit the exponential increase in publications seen with fibromyalgia during the 1990s (see Fig. 1 ). A final categorical comparison provided in Fig. 1 is a comparable summary of publications about biceps tendinitis, which is a localised soft-tissue pain condition. Even though that condition is more common than fibromyalgia or myofascial pain syndrome in the general population, there were only 140 referenced publications between 1948 and 2010.
It is interesting to note that the number of publications about fibromyalgia began to plateau after the year 2000. There are several possible explanations for this phenomenon. Certainly, it is possible that interest in this condition was beginning to wane after 10 years of vigorous activity and growth. Perhaps some physicians thought that there was nothing left to learn, according to an anonymous quote, “I have finished the internet, there is nothing left to surf”…, or as Charles H. Duell, Director of the United States Patent office in 1899, was incorrectly rumoured to have said (paraphrased): “Everything that can be invented has (already) been invented.” Duncan Gordon did not think everything was known about fibromyalgia when he made the following statement: “If what some of us call fibromyalgia is ever to be better managed, more research is required to identify the many factors that seem to cause and perpetuate this vexing medical problem.”
Then too, many of the investigators who had so actively espoused the condition in the ‘early days’ may have been stepping down from their academic careers and younger investigators were not shouldering the burden at the same rate.
A subtle, but perhaps more interesting possibility is that an increasing number of authors uncomfortable with the “fibromyalgia wars” (as Wolfe has described the controversy) have adopted different terminology to index their work in this field . For example, there appears to be a trend towards collectively referring to fibromyalgia and other conditions in the “same family” as ‘chronic widespread pain’, so this term may gradually take over as a proxy for fibromyalgia in some settings. That concept is supported by the observation that the term was not often used as a keyword before the year 2000; but, since then, the number of publications using that indexing term has grown and already totals 243 in just 10 years. Fig. 1 includes a composite curve showing the sum of the publications using the term ‘fibromyalgia’ with those indexed as chronic widespread pain. Even the curve of that combination shows a decline in slope compared with that of fibromyalgia publications during the span between 1990 and 2000.
So where does chronic widespread pain fit in the distribution of pain in the community? In an epidemiology study designed to quantify the prevalence of fibromyalgia in the United States general population, Wolfe et al. made random calls to homes in Wichita, Kansas to determine who in the household was experiencing musculoskeletal pain and to characterise the nature of their symptoms. Briefly, their findings were that nearly 60% of the general public was not affected by musculoskeletal pain at a given point in time. Nearly 30% had acute and/or regional pain symptoms and about 10% had chronic widespread pain. A portion of those with chronic widespread pain were examined to determine the proportion who would meet the 1990 ACR RCC by exhibiting pain to digital palpation at 11 or more of the anatomically defined tender points. The number who thus met the criteria and could be classified as having fibromyalgia was about 2% or two-tenths of those with chronic widespread pain. At issue since the publication of that report has been the question: “What is the appropriate diagnosis for the remaining 8% of those with chronic widespread pain but not meeting criteria for fibromyalgia?”
Another reasonable question is: “Why even make the diagnosis of fibromyalgia”? Actually, it was argued that making that diagnosis of fibromyalgia facilitated the illness behaviour in these patients . White and Thompson studied this question and found no worsening of symptoms or increase in disability after the diagnosis of fibromyalgia had been established . A reason that clinicians often mention for why they favour making the diagnosis of fibromyalgia is that patients are very grateful to finally have a name for the complex of symptoms they experience. Another reason is the evidence that a valid diagnosis of fibromyalgia can reduce health-care costs at least in the short term . Whether the clinical concern is the 2% of the general population who have fibromyalgia according to the 1990 ACR RCC or perchance the clinical entity that expands out to represent the 10% of the general population who have chronic widespread pain, the research endeavour which establish pathogenesis and develop medicinal intervention is in need of a clear mechanism of disease and a well-defined therapeutic target. If clinicians cannot make a diagnosis, biological research will not have the necessary tools to study the pathogenesis and will make no progress towards more effective therapy. Even when the clinical entity under study is narrowly defined, as in the case of the fibromyalgia according to the 1990 ACR RCC, it is clear that there are subgroups identifiable, based on clinical and on biological differences . The numbers of subjects populating different subgroups may be influenced by the diagnostic method used (more on this idea later). Clinical research studies, and particularly randomised clinical therapeutic trials, conducted over the past 20 years (since publication of the 1990 ACR RCC) have required that the diagnosis be made on the basis of the 1990 ACR RCC. Despite that, all three of the pharmaceutical agents currently approved by the United States Food and Drug Administration adequately manage only about 50% of fibromyalgia patients . Effective therapy may ultimately depend on biological identification of subgroups, which then can be expected to respond differently to each of several mechanism-focused interventions.
The 1990 ACR RCC dramatically aided the study of fibromyalgia during the 1990s. With widely accepted criteria, it was possible to conduct research studies on uniform patient populations recruited from diverse sites around the world. Because of the uniformity, there was reasonable certainty that study patients were comparable. It was possible to conduct physiology, imaging, pathogenesis and clinical therapy studies . On that basis, epidemiology studies could be conducted all over the world to establish the prevalence of fibromyalgia in different countries and ethnic populations. Those gains were enormous for fibromyalgia, and rapidly allowed a picture of this subpopulation of chronic widespread pain to emerge that could not have been accomplished without a uniform and widely accepted research classification. On the other hand, the 1990 ACR RCC also had weaknesses and these have been regularly pointed out by its critics . For example, the 1990 ACR RCC were designed and validated for the classification of fibromyalgia patients for research studies, but were never validated for clinical diagnosis. Despite that, physicians in clinics around the world began to use the 1990 ACR RCC to make the diagnosis of fibromyalgia on their patients. Even though they were presumably making the diagnosis of fibromyalgia by the 1990 ACR RCC, it is believed that many clinicians were not properly performing or interpreting the tender-point examination. Some psychiatrists were unhappily excluded from making the diagnosis of fibromyalgia on that basis because the historic philosophy of their specialty did not allow them to physically touch patients, as would have been required for them to perform the tender-point examination, which is key to the 1990 ACR RCC. Epidemiology studies on the prevalence of fibromyalgia were difficult to perform because confident diagnosis required at least a sample of the patients with widespread pain to be examined for tender points. Finally, both components of the 1990 ACR RCC were based on the domain of pain (including the tender-point examination, which was a semiobjective finding of a low pain threshold, allodynia), but they completely ignored the co-morbid domains so troublesome to most fibromyalgia patients. There clearly was a need for newly validated clinical criteria that would focus on co-morbid manifestations of fibromyalgia, such as sleep dysfunction, headache, cognitive insecurity, affective manifestations, fatigue, chest pain, irritable bowel and bladder irritability.
It was on the basis of that need that the development of a new approach to clinical diagnosis of fibromyalgia was undertaken . Some had advocated discarding the 1990 ACR RCC, but the approach that was ultimately taken was to establish the new 2010 ACR Fibromyalgia Diagnostic Criteria (FDC), while viewing the 1990 ACR RCC as the gold standard. By gold standard, in this case, is meant simply that those patients identified as meeting 2010 ACR FDC were checked against those meeting 1990 ACR RCC at an earlier time in their medical history to determine how well the two criteria agreed. Again, the task was guided by Dr. Fred Wolfe.
The approach was to quantify a widespread pain index (WPI) by physician interview to determine how large a proportion of the patient’s anatomy was experiencing pain. Table 2 provides a listing of the areas of the body where the existence of pain would contribute to the WPI. Each affected area increased the WPI by one point, with a range of possible scores from 0 to 19.
| A. Widespread pain index (WPI) 0–19 | |||
| Ask about pain in 19 body regions shown below (each relevant item from the list counts as one point): | |||
| Jaw, Rt. | Upper Arm, Rt. | Upper Back | Upper Leg, Rt. |
| Jaw, Lt. | Upper Arm, Lt. | Lower Back | Upper Leg, Lt. |
| Neck | Lower Arm, Rt. | Hip (buttock, trochanter), Rt. | Lower Leg, Rt. |
| Shoulder girdle, Rt. | Lower Arm, Lt. | Hip (buttock, trochanter), Lt. | Lower Leg, Lt. |
| Shoulder girdle, Lt. | Chest | Abdomen | |
Related posts:
Chronic widespread pain or fibromyalgia? That is the question
Chronic widespread pain: From peripheral to central evolution
Trauma and work-related pain syndromes: Risk factors, clinical picture, insurance and law interventions
Translational musculoskeletal pain research
Non-pharmacological treatment of chronic widespread musculoskeletal pain
Pharmacotherapy of fibromyalgia
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