The ACR Criteria for Fibromyalgia: The Good and the Bad
Clauw, Daniel J. MD
The American College of Rheumatology criteria have been both bad and good for fibromyalgia 1. When they were published in 1990, this is what we thought fibromyalgia was: chronic widespread pain and the 11 of 18 tender points. If this is your view of fibromyalgia, then fibromyalgia is really no different than other rheumatic diseases like osteoarthritis or rheumatoid arthritis or lupus-a discrete illness. In 1990, we also thought that the tenderness was confined to certain areas of the body, or at least more accentuated in certain areas of the body, which we refer to as tender points. Finally, another misconception that exists to this day in many people's mind is that psychological and behavioural factors are always present in people with fibromyalgia and always make them worse.
A more contemporary view of fibromyalgia is that rather than being a discrete illness, it is a part of a huge continuum of pain and somatic syndromes. It happens to be what we, as rheumatologists, are most comfortable calling it. But these individuals have pain throughout their entire body that isn't due to damage or inflammation, and there's a great deal of scientific evidence that this is one large spectrum of illness that includes fibromyalgia, irritable bowel, and temporomandibular joint (TMJ) syndrome-as well as a number of other conditions that I'll talk about later. Even if we use the American College of Rheumatology (ACR) criteria to diagnose fibromyalgia (i.e., on the basis of widespread tenderness and pain), people don't just have tenderness and pain. They have a lot of other somatic symptoms besides pain and tenderness. And, again, psychological and behavioral factors only play negative roles in some individuals.
We also now know that the entire individual with fibromyalgia is tender, and that there is nothing magical about tender points. These are merely areas where everyone is more tender. But fibromyalgia patients are also much more tender wherever you apply pressure, including areas previously considered to be control points. In fact, in our research group, when performing sophisticated imaging studies, we push on the thumbnail because we found that the thumbnail is just as tender (relative to that same region in a healthy control) as any of the tender points. Fred Wolfe was the first to point this out. He suggested that we should abandon this old term that used to be called control points and call them high-threshold tender points; areas like the forehead and the thumbnail and the anterior tibial region are just areas where all of us have a higher pain threshold.
These are many other problems with ACR criteria and specifically with tender points. We didn't know any of this in 1990, so I'm not being critical of the people who were involved in developing the ACR criteria because they have been wonderful in standardizing research into fibromyalgia. But we didn't know that tender points are actually not a very good measure of tenderness. In 1997, Wolfe published an article where he looked at some of the data that he collected in population-based studies. He had found that the number of tender points an individual has is highly correlated with the number of measures of distress-of anxiety, depression, and distress 2. What he said in that article was that tender points are a sedimentation rate for distress. Since then, our group and others have shown that other more sophisticated measures of tenderness, such as where you give people stimuli randomly when they can't anticipate what the next stimulus is going to be, are just as abnormal in people with fibromyalgia, but these are not at all related to the level of distress of the individual 3. So people with fibromyalgia are indeed much more tender, or they have what we would call a left-shift in their stimulus-response function with respect to pressure. So the take-home message is that fibromyalgia patients are much more tender even using more sophisticated measures that are not confounded by distress. However, tender points are not a very good measure of tenderness. Tender points are part a measure of tenderness and part a measure of how anxious and depressed an individual is.
I might be the first author that I know of that's been able to get away with writing a chapter in textbook regarding fibromyalgia without having an illustration of a woman with 18 dots on it, because I think that the longer that we highlight the ACR criteria and highlight these 18 areas of the body, the longer physicians are going to think that there is something uniquely wrong with those 18 areas of the body rather than realize that this is a diffuse, central problem with pain processing. This gives an inappropriate impression about the nature of fibromyalgia when you put those 18 dots and they all happen to be located over muscle-tendon junctions and people sort of think, Well, that's where the problem is, rather than realizing that this is a problem in the central nervous system with the way people are processing pain or sensory information. Our group hypothesizes that this is actually a more global problem with sensory processing, not just pain processing, because people with this spectrum of illness are sensitive to a number of different types of stimuli rather than just somatic pain.
I think one of the other disservices that the ACR criteria has done is that they've deluded us into thinking that fibromyalgia occurs almost exclusively in women. If you use the ACR criteria, 92% of the people in the population who are identified as meeting those criteria are females. But if you break down the criteria into the 2 elements, (1) chronic widespread pain and (2) 11 of 18 tender points, women are only 1[1/2] times as likely as men to have chronic widespread pain, but women are 11 times as likely as men to have 11 of 18 tender points. So what we've done with the ACR criteria is take an illness that is probably only about 1[1/2] times more commonly in women and make physicians think that this occurs only in females. This is similar to what we did a couple of decades ago when I was trained as a rheumatologist, when we were taught that ankylosing spondylitis only occurred in males. When that's what we were taught, then we only thought of the diagnosis of ankylosing spondylitis in men, even though later data showed that the prevalence of AS is very similar in men and women.
The same thing happens now with women versus men in chronic pain. Men who come in with the same exact symptoms and physical examination as women with fibromyalgia are more likely to be labeled with regional pain syndromes such as osteoarthritis, because if you do X-ray after X-ray (or worse yet MRI after MRI) you will always find something wrong. I used to have a diagnostic test called the X-ray jacket sign because when we went to the VA clinic, they would pull the X-ray jackets on all patients (before the X-rays were digitalized). I joked that if you could pull 10 consecutive musculoskeletal X-rays out and none of them were abnormal, that was a diagnostic test for fibromyalgia. And we had many men in the rheumatology clinic that we were seeing who had been labeled as osteoarthritis or chronic low back pain, who clearly had fibromyalgia. But the diagnosis carried for years and years in their chart was a regional pain syndrome such as osteoarthritis, even though there were inadequate radiographic findings to support this, and they typically did not respond very well to treatments for peripheral pain.
Then the last thing that people should be aware of with tender points, and that is that 11 is a totally arbitrary number. Robert Katz has published articles recently talking about how different types of criteria function equally well. And he and I, and almost everyone in the fibromyalgia field, agree that the ACR criteria should not be used in clinical practice to diagnose fibromyalgia. They never were intended for that purpose. They were intended to standardize research studies. And they don't function very well at all when you use them in routine clinical practice.
Every subspecialist that I know, except perhaps radiologists and pathologists, sees patients that was as rheumatologists call fibromyalgia and has one or more names for the symptoms in the area of the body they are responsible for. It is not until you realize the entirety of the problem, like the pharmaceutical industry now does, that you understand that this is one large problem that needs to be addressed in primary care, rather than something that's just been bestowed upon us in rheumatology because we have to deal with these fibromyalgia patients.
Fibromyalgia: Update on Mechanisms and Management
JCR: Journal of Clinical Rheumatology:Volume 13(2)April 2007pp 102-109
Clauw, Daniel J. MD
From the *Division of Rheumatology, Chronic Pain and Fatigue Research Center, Clinical and Translational Research, University of Michigan Medical Center, Ann Arbor, Michigan. From Rheumatology Grand Rounds at Rush University Medical Center, Chicago, IL, USA. Editors: Robert S. Katz, MD, and Joel A. Block, MD.
References: 1. Wolfe F, Symthe HA, Yunus MB, et al. The American college of rheumatology 1990 criteria for the classification of fibromyalgia. Report of the Multicenter Criteria Committee. Arthritis Rheum. 1990;33:160-172.
2. Wolfe F. The relation between tender points and fibromyalgia symptom variables: evidence that fibromyalgia is not a discrete disorder in the clinic. Ann Rheum Dis. 1997;56:268-271.
3. Petzke F, Gracely RH, Park KM, et al. What do tender points measure? Influence of distress on 4 measures of tenderness. J. Rheumatol. 2003;30:567-574.