A report and opinion on the preliminary guidelines for the
clinical diagnostic criteria for fibromyalgia

Robert Bennett, MD

The 1990 American College of Rheumatology Classification Criteria for fibromyalgia have been the gold-standard criteria for diagnosing this disorder for the last 20 years (1). These criteria classify fibromyalgia as a disorder characterized by widespread pain and undue tenderness to moderate palpation pressure in ≥11 out of 18 specified locations (tender points).  In general classification criteria are strictly intended for use in epidemiological studies and not necessarily for clinical diagnosis. However the 1990 paper did note, “the sensitivity of the criteria suggests that they may be useful for diagnosis as well as classification”. Over the ensuing 20 years, it has become apparent that some patients with typical FM symptoms do not meet the criteria of tender points, yet no other diagnosis is apparent on follow up.  In some other cases, patients may experience worthwhile improvement to the extent that they no longer meet the tender point criteria; do they now suddenly cease to have FM? Lastly the clinical evaluation of tender points is an acquired skill that is not routinely taught in medical school and is thus seldom or improperly used by primary care physicians (2). Importantly the 1990 criteria do not embrace the many other symptoms that are commonly reported by FM patients and hence they define a disorder that is based on the experience of pain alone (3). It is noteworthy that many other common FM symptoms, such as fatigue, poor sleep, cold sensitivity etc. and were evaluated in the development of the 1990 criteria and found not to enhance the diagnosis. In this respect the discussion in the 1990 paper noted: “Of particular interest was the finding that the simultaneous occurrence of sleep disturbance, fatigue, and morning stiffness, re­quired in certain previous criteria sets, was found in only 56% of patients ……………. no combination or set of combinations of tender points and symptoms could be found that performed better than the tender point and widespread pain criteria”. Thus the 1990 criteria did not use these other common manifestations of FM in its final recommendations, based on strictly statistical reasons relating to sensitivity and specificity. Bearing these critiques in mind, there has been an increasing awareness that the 1990 criteria need revising, especially when it comes to making a diagnosis of FM in the clinical setting (3).

Herein, I discuss a recent article that attempts to provide alternative diagnostic criteria that also includes a measurement of symptom severity (4). These new preliminary criteria were based on an analysis data from previously diagnosed FM patients (either by ACR criteria or the physicians “clinical” impression) and patients with non-inflammatory pain disorders, such as osteoarthritis, bursitis, tendinitis, neck pain and back pain. All subjects were culled from the practices of 32 “interested” rheumatologists. The data analysis was based on a 2 stage design. The study that led to this publication was funded by Lilly Research Laboratories; this sponsor did not participate in the design or analysis of the study, nor did they review the manuscript.

 First stage

All subjects (#610) completed the following 5 questionnaires before seeing the physician:

1)     Whether they had pain in any of 19 locations (the Widespread Pain Index or WPI).

2)     Rating of 4 symptoms (pain, fatigue, ability to sleep and un-refreshing sleep) a 0-10 scale.

3)     The Health Assessment Questionnaire II functional disability scale.

4)     The number of medications used.

5)     How many of 56 designated symptoms they experienced.

All physicians (#32) independently (i.e. without looking at the patients’ responses) completed the WPI, the Symptom Severity Scale (SS), and also performed an ACR defined tender point evaluation. The SS was composed of 3 questions (fatigue, cognitive problems, waking un-refreshed and extent of somatic symptoms*) rated on a scale of 0-3; thus it had a range of 0-12.
*The extent of somatic symptoms was reduced to a 0-3 scale from a list of 41 symptoms. 
They also noted if the subjects had any of the following problems: muscle pain, muscle weakness, irritable bowel syndrome, fatigue, cognitive problems, headaches, abdominal pains/cramps, paresthesias, dizziness, sleep problems, depression, anxiety, constipation, diarrhea, interstitial cystitis and muscle tenderness. Lastly, they indicated their certainty of the prior diagnosis on a 0-10 scale (0=very uncertain, 10= very certain).

 Second stage

This stage was completed only by the physicians (#22), not the patients. Also, the 10 FM experts did not take part in this stage. From the same WPI list used by the patients from the first stage, they rated the pain extent as 0-3, 4-6, 7-10 or ≥ 11. They also performed:

1)     The ACR tender point evaluation

2)     Recorded the presence/absence of muscle pain

3)     Recorded the presence/absence muscle tenderness

4)     Recorded the presence/absence irritable bowel syndrome

5)     Provided a rating of somatic symptoms from a list of 41 symptoms (scaled as:0= few or no symptoms, 1=mild # of symptoms, 2= moderate # of symptoms, 3=great # of symptoms)

6)     Recorded the 3 categorical scales of: 1. un-refreshing sleep, 2. cognitive problems and 3. 
 fatigue (scaled 0=no problem, 1=mild problem, 2=moderate problem and 3=severe 
 problem).

The phase 2 study data were used to determine if a shortened questionnaire would work as well in categorizing fibromyalgia, compared to the more detailed phase 1 assessments.

 Analysis

Data from the first stage was analyzed from 3 viewpoints: 1.A short set that included WPI and the categorical scores for pain, fatigue, sleep disturbance, mood, cognitive problems, un-refreshing sleep and somatic symptoms. 2. An intermediate set that included all the variables in the short set plus all of the individual somatic symptoms. 3. The full set included all of the study variables. Based on a series of standard statistical tests (t tests, regression analysis, correlation analyses, classification tree analyses) as well as some more “sophisticated” analyses (“out of bag” error results, random forest analyses, Gini index, recursive partitioning R analysis); these data were presented as a probability density function; the author advises the reader to think of this as a “smoothed-out” version of a histogram.

 Results

Some 258 valid FM patients and 256 control patients were entered into the final analysis. Of the FM subjects, 63.6.6% had an ACR based diagnosis the rest had a symptom based diagnosis. All subjects were categorized into 3 groups based on prior diagnosis and ACR classification: criteria status: 196 patients 38.1% had "current" fibromyalgia (ACR clas­sification criteria positive, physician fibromyalgia diagno­sis positive), 67 13.0% had "prior" fibromyalgia (ACR classification criteria negative, physician fibromyal­gia diagnosis positive), and 48.1% were control subject (neither current nor prior fibromyalgia patients). These 3 groups clearly differed on clinical features, symptom severity and tender point score. As might be expected the "current" fibromyalgia had the most symptoms and highest severity score, with the "prior" fibromyalgia group having an intermediate scores. The tender point count provided the clearest distinction between groups. Some 25% of patients considered to have a diagnosis of FM by their physicians failed to satisfy the ACR classification criteria.

Based on some quite complicated statistics, it was found that a clinical diagnosis of FM (i.e. without the use of tender points) was best based on a combination of the WPI score and a symptom severity scale (referred to as SS). The final recommendations for a clinical case definition of FM was as follows:

A clinical diagnosis of fibromyalgia can be made if:

1.  The WPI ≥7 and the SS ≥5  or  the WPI 3–6 and the SS ≥9.
2.  Symptoms have been present at a similar level for at least 3 months.
3.  The patient does not have a disorder that would otherwise explain the pain.

The WPI and SS can be obtained from the following tables:

1. Pain Locations (WPI): Check each location where patient has pain – then total score (0-19)

2. Symptom Severity Scale (SS): Check severity of each problem – then total score (0-12)

§ Somatic symptoms
How many of these 41 symptoms does the patient have –score 0 to 3 on the total symptom burden.
These were then scaled as: 0= few or no symptoms, 1=mild # of symptoms, 2= moderate # of symptoms, 3=great # of symptoms). Then add this number to the “somatic symptoms” in the Symptom Severity Scale table above.

 Opinion

There is little doubt that these new criteria will be positive in most patients with ACR defined fibromyalgia and also many patients who most experienced physicians would label as having FM, in the absence of 11 or more out of 18 defined tender points; as was indeed found in this study. It is relevant to note that the authors make the point that “the diagnostic criteria suggested here are not meant to replace the ACR classification criteria”. However, in the discussion they note that “if, as we expect, the diagnostic criteria perform well, it seems possible that the ACR classification criteria might be withdrawn.”

It is worth noting that the most discriminating clinical feature in this current study was still the ACR tender point evaluation; as it was in the original study that led up to the 1990 classification criteria (5). However, the focus of this study was to devise clinical diagnostic criteria for FM that would be effective in the absence of a tender point examination. This leads to the question as to whether one would now be justified in making a diagnosis of FM without any examination. In other words can FM be a disorder defined solely by symptoms, similar to DMSM defined psychiatric diagnoses?  It is relevant to note that the discussion does stress the need for “an appropriate clinical assessment”, but I have a concern that this will inevitably be omitted by some time-stressed physicians. It is my opinion that any potential criteria should demand a carefully structured physical examination and not be left to the physician’s whim. The management of FM demands an assessment of all other potential sources of pain, especially those of musculoskeletal origin, such as osteoarthritis and soft tissue pain. In regards to the latter, an evaluation of active myofascial pain trigger points is especially relevant. It is now apparent that the 1990 ACR defined tender points are in fact typical myofascial trigger points in most locations (6), and that they are an important contributor to the FM pain experience (7;8). These relatively recent research findings have cast FM tender points in an important new light; they need to be carefully considered before the “baby is tossed out with the bathwater”(9). Thus, while it may not be a strict requirement for the new preliminary diagnosis, it is my opinion that a competent evaluation of a patient with probable FM should include not only a examination of the 1990 ACR tender points but also all potential myofascial trigger points, as dictated by the history. It is also worthy of comment that the controls in this study excluded patients with inflammatory rheumatic disorders, thus the specificity of these preliminary criteria is not known. For instance a patient with rheumatoid arthritis may well be “preliminary” criteria positive, but should be excluded by a thorough clinical evaluation. Whether a patient can have concomitant RA and FM (as occurs in about 20% of cases) with use of the new criteria is not clear.

I general, I consider these preliminary diagnostic criteria to be just that – “preliminary”. It is a good first step in trying to come up with easily applied diagnostic criteria and doing away with the need to define FM purely on the symptom of widespread pain and a certain number of tender points. I certainly applaud the need to incorporate symptoms other than pain in the diagnosis of FM. But I have reservations about basing the diagnosis purely on symptoms, as this makes it a diagnosis that can easily be “faked” and may eventually lead to the designation of FM as a “wastebasket diagnosis”, as was often done before the ACR classification criteria were introduced in 1990.

I believe these preliminary symptom criteria can be improved upon; for instance the duality of the diagnostic logarithm make them rather clumsy to apply, and may, in reality be defining 2 subgroups of chronic pain. I would strongly recommend a reconsideration of the role of tenderness, as part of any new diagnostic recommendations. While I endorse eliminating the 1990 ACR tender point criteria, I favor replacing them with a more objective and/or simpler measure of tenderness. What this should be remains to be determined. But there have been studies that suggest the feasibility of using something as simple as assessing the pain threshold during the taking of blood pressure with a sphygmomanometer cuff (10) or the more sophisticated computerized cuff pressure algometry, as described by Jespersen and colleagues (11). Harden and others have reported that 3 tender points provide as much classification accuracy as the use of all 18 points (12).  Another alternative is to further explore the increased reactivity of FM patients (so called “central sensitization”) in a relatively simple procedure known as nociceptive reflex testing (13); a test that can be administered in most units performing routine EMG/NCV tests (14). When all is said and done, the essence of fibromyalgia combines pain and stiffness along with other characteristic symptoms (especially fatigue, un-refreshing sleep and general reactivity) with an undue tenderness to touch (15).
The recent OMERACT consensus, reporting on the key symptom domains that should be assessed in FM, recommends that “tenderness” be included as a separate domain; and notes that: “physiologically, this would be logical, because spontaneous and evoked pain involve different pathways. Furthermore, it mirrors the need to assess patient-reported pain and tender joint count in rheumatoid and psoriatic arthritis”(16).

Omitting “undue sensitivity to touch” from any diagnostic criteria for fibromyalgia, will in my opinion, disparage one seminal feature that is the "essence" of fibromyalgia.  The definitive diagnosis of this common disorder still remains a formidable challenge. I hope that the publication of these preliminary criteria will spur further efforts to meet the challenge.

       References

     (1)   Wolfe F, Smythe HA, Yunus MB, Bennett RM, Bombardier C, Goldenberg DL, et al. The American College of Rheumatology 1990 criteria for the classification of fibromyalgia: Report of the Multicenter Criteria Committee. Arth Rheum 1990;33:160-72.

     (2)   Harth M, Nielson WR. The fibromyalgia tender points: use them or lose them? A brief review of the controversy. J Rheumatol 2007 May;34(5):914-22.

     (3)   Wolfe F. New American College of Rheumatology criteria for fibromyalgia: a twenty-year journey. Arthritis Care Res (Hoboken ) 2010 May;62(5):583-4.

     (4)   Wolfe F, Clauw DJ, Fitzcharles MA, Goldenberg DL, Katz RS, Mease P, et al. The American College of Rheumatology preliminary diagnostic criteria for fibromyalgia and measurement of symptom severity. Arthritis Care Res (Hoboken ) 2010 May;62(5):600-10.

     (5)   Wolfe F, Smythe HA, Yunus MB, Bennett RM, Bombardier C, Goldenberg DL, et al. The American College of Rheumatology 1990 Criteria for the Classification of Fibromyalgia. Report of the Multicenter Criteria Committee. Arthritis Rheum 1990 Feb;33(2):160-72.

     (6)   Ge HY, Wang Y, Danneskiold-Samsoe B, Graven-Nielsen T, Arendt-Nielsen L. The Predetermined Sites of Examination for Tender Points in Fibromyalgia Syndrome Are Frequently Associated With Myofascial Trigger Points. J Pain 2009 Nov 13.

     (7)   Ge HY, Nie H, Madeleine P, Danneskiold-Samsoe B, Graven-Nielsen T, Arendt-Nielsen L. Contribution of the local and referred pain from active myofascial trigger points in fibromyalgia syndrome. Pain 2009 Dec 15;147(1-3):233-40.

     (8)   Staud R, Nagel S, Robinson ME, Price DD. Enhanced central pain processing of fibromyalgia patients is maintained by muscle afferent input: a randomized, double-blind, placebo-controlled study. Pain 2009 Sep;145(1-2):96-104.

     (9)   Tastekin N, Uzunca K, Sut N, Birtane M, Mercimek OB. Discriminative value of tender points in fibromyalgia syndrome. Pain Med 2010 Mar;11(3):466-71.

    (10)   Vargas A, Vargas A, Hernandez-Paz R, Sanchez-Huerta JM, Romero-Ramirez R, mezcua-Guerra L, et al. Sphygmomanometry-evoked allodynia-a simple bedside test indicative of fibromyalgia: a multicenter developmental study. J Clin Rheumatol 2006 Dec;12(6):272-4.

    (11)   Jespersen A, Dreyer L, Kendall S, Graven-Nielsen T, rendt-Nielsen L, Bliddal H, et al. Computerized cuff pressure algometry: A new method to assess deep-tissue hypersensitivity in fibromyalgia. Pain 2007 Jan 24;.

    (12)   Harden RN, Revivo G, Song S, Nampiaparampil D, Golden G, Kirincic M, et al. A critical analysis of the tender points in fibromyalgia. Pain Med 2007 Mar;8(2):147-56.

    (13)   Desmeules JA, Cedraschi C, Rapiti E, Baumgartner E, Finckh A, Cohen P, et al. Neurophysiologic evidence for a central sensitization in patients with fibromyalgia. Arthritis Rheum 2003 May;48(5):1420-9.

    (14)   France CR, Rhudy JL, McGlone S. Using normalized EMG to define the nociceptive flexion reflex (NFR) threshold: further evaluation of standardized NFR scoring criteria. Pain 2009 Sep;145(1-2):211-8.

    (15)   Bennett RM, Friend R, Jones KD, Ward R, Han BK, Ross RL. The Revised Fibromyalgia Impact Questionnaire (FIQR): validation and psychometric properties. Arthritis Res Ther 2009 Aug 10;11(4):R120.

    (16)   Choy EH, Mease PJ. Key symptom domains to be assessed in fibromyalgia (outcome measures in rheumatoid arthritis clinical trials). Rheum Dis Clin North Am 2009;35(2):329-37.