Transcript The Instability of Fibromyalgia Diagnosis

The Instability of Fibromyalgia Diagnosis: Associations with Measures of Severity
F
1
Wolfe ,
2
Clauw ,
3
Fitzcharles ,
4
Goldenberg ,
1
Harp ,
5
Katz ,
DJ
MA
DL
KA
RS
PJ
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10
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KD Michaud , AS Russell , IJ Russell , JB Winfield and MB Yunus ,
1National
2U
3MGH,
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Mease ,
4Newton-Wellesley
Data Bank, Wichita, KS,
Michigan, Ann Arbor, MI,
Montreal, QC,
Hosp, Newton, MA,
5Rheumatology Associates, Chicago, IL, 6Seattle Rheumatology, Seattle, WA,7U Neb Med Center and NDB, Omaha, NE,
8U Alberta, Edmonton, AB,9U TX Hlth Sci Ctr, San Antonio, TX, 10UNC, Chapel Hill, NC, 11U IL Coll of Med, Peoria, IL
Abstract
Methods (continued)
Purpose: To determine the percent of patients diagnosed with Fibromyalgia (FM)
who do not satisfy American College of Rheumatology (ACR) criteria; to
determine the comparative characteristics of these patients, and to investigate the
use of ACR criteria among rheumatologists.
We required fibromyalgia study patients to have a previous diagnosis of fibromyalgia.
They were enrolled as they appeared in the clinic for usual care (not by being
recalled) and without consideration of current diagnosis, severity, or other
characteristics. Fibromyalgia subjects must have been diagnosed with fibromyalgia by
the same examining rheumatologist prior to date of study assessment. Patients
diagnosed with fibromyalgia could have been diagnosed on clinical grounds or by
ACR criteria (10). It was not a requirement of diagnosis to have satisfied ACR
criteria. Of the 30 physicians contributing valid patients to Phase 1 of the study, 6
used only clinical diagnosis, 9 used only ACR diagnosis, and 15 diagnosed some
patients using clinical methods and some patients using ACR methods. Among the
expert physicians 4 used clinical diagnosis, 4 used ACR diagnosis, and 2 used both
methods.
Methods: As part of a two-phase multicenter study to develop simple clinical
criteria for fibromyalgia, we evaluated 920 FM patients and pain controls. FM
patients were consecutive FM patients seen during routine practice who carried a
diagnosis of FM made previously by the examining rheumatologist. Patients
underwent a detailed interview and examination, including TP examination and
assessment of the extent of widespread pain using a widespread pain index (WPI).
Physicians enrolled 258 valid patients in Phase I whose clinical diagnosis was
fibromyalgia and 256 who were control subjects. We report here on the Phase I
study because it also included patients' self-report data.
Results: 25.4% of patients being treated for FM did not satisfy ACR criteria. We
called this group "prior fibromyalgia." In addition, rheumatologists had not used
ACR criteria in 36.4% of fibromyalgia diagnoses. There was a clear difference in
clinical findings and symptom severity among the groups, with prior fibromyalgia
generally occupying the midpoint between current fibromyalgia and controls
(Table 1). With respect to diagnostic variables, the TP count (15.9 vs. 7.9) and the
WPI (11.4 vs. 7.2) were significantly less abnormal in prior FM than in ACR (+)
patients. These differences also extended to non-criteria severity measures such as
fatigue, unrefreshed sleep, somatic symptoms, cognition, function, and pain
medications. No set of class variables could be found that could adequately
separate prior FM from ACR (+) FM or control subjects.
Conclusion: ACR criteria do not adequately diagnose or describe the
characteristics of all FM patients in clinical practice. ACR criteria are not used by
a third of rheumatologists diagnosing fibromyalgia, and 25.5% of patients being
treated for fibromyalgia by rheumatologists do not satisfy these criteria. Current
FM criteria aggregate and confound diagnostic status and symptom severity,
features that should be separated to enable more adequate FM evaluation and
management.
Methods
Study subjects and physicians. We recruited study physicians by selecting
randomly from a list of 113 rheumatologists who were members of the American
College of Rheumatology (ACR) and who indicated an interest in participating in
the study after an email solicitation. We also included five physicians with known
fibromyalgia expertise from the executive committee.
Participating physicians had to be certain that they would see 10 fibromyalgia
patients and 10 non-inflammatory controls within a 4-month period. They had to
be experienced with fibromyalgia patients and the fibromyalgia tender point
examination. All physicians completed a short instructional questionnaire on the
Internet and satisfactorily completed a brief examination on study requirements
and methods. We required that the physician, not an assistant, complete physician
assessment forms and that patient forms could only be completed by the patient.
Control subjects were patients with non-inflammatory painful disorders such as neck
and back pain syndromes, osteoarthritis, tendonitis or similar disorders who had not
been diagnosed previously as having fibromyalgia and who were of the same sex and
were no more than ten years younger or ten years older than the fibromyalgia case. As
with fibromyalgia patients, control subjects must have had a prior control diagnosis.
Patients with any inflammatory rheumatic disorder (e.g., rheumatoid arthritis), active
cancer, fractures, defined neuropathic causes of pain, or other non-rheumatic causes
for pain were excluded from the study.
Results (continued)
Figure 1a. Distribution of key fibromyalgia variables in controls
and patients with current or prior fibromyalgia (Phase I).
Characteristics of patients by fibromyalgia status. There was a clear difference in
clinical findings and symptom severity among the groups, the current fibromyalgia
patients having the greatest symptom severity with prior fibromyalgia generally
occupying the severity scale midpoint between current fibromyalgia and controls
(table 1). However, for the count of patient endorsed somatic symptoms, the MD
somatic symptom scale and the symptom severity scale, prior fibromyalgia patients
had scores that were somewhat closer to current fibromyalgia patients than to
control subjects. Figures 1a & 1b shows differences between groups for key
variables. The tender point count (bottom right) demonstrates the clearest
distinction between groups, followed by unrefreshed sleep (bottom left). Prior and
current fibromyalgia patients had similar distributions of somatic symptoms counts
(upper right), while prior fibromyalgia had the WPI shifted somewhat to the left
(upper left). Taken as a whole, these data show that about 25% of patients
considered to have fibromyalgia by their physicians do not satisfy American
College of Rheumatology classification criteria for fibromyalgia, and that they
appear to have an intermediate severity position between fibromyalgia patients and
control subjects, except for somatic symptoms.
Table 1. Selected Clinical Characteristics of Patients with Current
or Prior Fibromyalgia, or who are Controls in Phase I
Figure 1b. Distribution of severity scores using ACR definition of
fibromyalgia by category of fibromyalgia diagnosis in Phases I
and II. A symptom severity scale score >6 identifies patients
satisfying the new diagnostic criteria in 92.3% of cases.
In Phase 1 we enrolled 610 patients from 32 referring physicians between Dec 2, 2008
and April 30, 2009.
Results
Demographics. Physicians enrolled 258 valid patients in Phase I whose clinical
diagnosis was fibromyalgia and 256 who were control subjects. Fibromyalgia subjects
were slightly older than controls, 54.6 (SD 12.9) vs. 52.3 (12.2) years, p = 0.035, but
did not differ by percent male (8.2% vs. 9.0) p = 0.732, percent non-Hispanic white
(86.8% vs. 85.9%) p = 0.770, or education level (14.2 (2.1) vs. 14.3 (2.2) years) p =
0.517.
Diagnosis and diagnostic methods. ACR criteria were used in 63.6% of fibromyalgia
diagnoses and clinical diagnosis was used in 36.4% of fibromyalgia diagnoses. At the
time of the study examination, 74.5% of patients who had been previously diagnosed
with fibromyalgia satisfied current ACR criteria and 2.0% of controls satisfied current
criteria. Based on these data, we categorized patients into three groups based on prior
diagnosis and current ACR criteria status: 196 patients (38.1%) with current
fibromyalgia (current ACR (+), physician fibromyalgia diagnosis (+)), 67 (13.0%)
with prior fibromyalgia (current ACR (-), physician fibromyalgia diagnosis (+)), and
251 (48.1%) who were neither current nor prior fibromyalgia patients (control
subjects) (table 1). Using a 0-10 physician certainty of prior diagnosis scale, the mean
certainties were: fibromyalgia 9.4, prior fibromyalgia 8.7, and control diagnosis 9.1.
Patients previously diagnosed by clinical criteria were more likely to be classified as
prior fibromyalgia (38.3%) compared with patients previously diagnosed by ACR
criteria (18.9%), p <0.001. The proportion of patients who were controls, or had prior
or current fibromyalgia did not differ between the group of 10 “expert” physicians and
the 20 clinical rheumatologists, p = 0.640.
The Symptom Severity Scale
The most important diagnostic variables were the widespread pain index (WPI) – a
measure of the number of painful body regions, and categorical scales for cognitive
symptoms, unrefreshed sleep, fatigue, and number of somatic symptoms. The
categorical scales were summed to create a symptom severity (SS) scale (Figure
1b).
Supported by a grant from Eli Lilly and Company
Conclusion
ACR criteria do not adequately diagnose or describe the characteristics of all FM
patients in clinical practice. ACR criteria are not used by a third of
rheumatologists diagnosing fibromyalgia, and 25.5% of patients being treated for
fibromyalgia by rheumatologists do not satisfy these criteria. Current FM criteria
aggregate and confound diagnostic status and symptom severity, features that
should be separated to enable more adequate FM evaluation and management.