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
All subjects (#610) completed the following 5 questionnaires
before seeing the physician:
Whether they had pain in any of 19 locations (the Widespread
Pain Index or WPI).
Rating of 4 symptoms (pain, fatigue, ability to sleep and
un-refreshing sleep) a 0-10 scale.
The Health Assessment Questionnaire II functional disability
The number of medications used.
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).
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:
The ACR tender point evaluation
Recorded the presence/absence of muscle pain
Recorded the presence/absence muscle tenderness
Recorded the presence/absence irritable bowel syndrome
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)
Recorded the 3 categorical scales of: 1. un-refreshing sleep, 2. cognitive problems and
fatigue (scaled 0=no
problem, 1=mild problem, 2=moderate problem and 3=severe
The phase 2 study data were used to determine if a shortened
questionnaire would work as well in categorizing fibromyalgia,
the more detailed phase 1 assessments.
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.
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
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
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
The patient does not have a disorder that would otherwise
explain the pain.
The WPI and SS can be obtained from the following
1. Pain Locations (WPI): Check each location
where patient has pain – then total score (0-19)
L. Outer Hip
R. Outer Hip
L. Upper arm
L. Upper Leg
R. Upper arm
R. Upper Leg
L. Lower arm
L. Lower Leg
R. Lower arm
R. Lower Leg
2. Symptom Severity Scale (SS): Check severity of each problem –
then total score (0-12)
Somatic symptoms §
§ 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.
Irritable bowel syndrome
Thinking or remembering problem
Pain/cramps in the abdomen
Pain in the upper abdomen
Ringing in ears
Loss of/change in taste
Shortness of breath
Loss of appetite
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
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.
(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
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