Scandinavian Journal of Rheumatology
ISSN: 0300-9742 (Print) 1502-7732 (Online) Journal homepage: http://www.tandfonline.com/loi/irhe20
Implications of proposed fibromyalgia criteria across other functional pain syndromes N Egloff, R von Känel, V Müller, UT Egle, G Kokinogenis, S Lederbogen, B Durrer & S Stauber To cite this article: N Egloff, R von Känel, V Müller, UT Egle, G Kokinogenis, S Lederbogen, B Durrer & S Stauber (2015): Implications of proposed fibromyalgia criteria across other functional pain syndromes, Scandinavian Journal of Rheumatology To link to this article: http://dx.doi.org/10.3109/03009742.2015.1010103
Published online: 16 Jun 2015.
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Date: 16 September 2015, At: 07:11
Scand J Rheumatol 2015;iFirst article:1–9
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Implications of proposed fibromyalgia criteria across other functional pain syndromes N Egloff1,2, R von Känel3,4, V Müller1, UT Egle5, G Kokinogenis1,2, S Lederbogen1, B Durrer1, S Stauber1 1
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Department of General Internal Medicine, Division of Psychosomatic Medicine, Inselspital, Bern University Hospital, and University of Bern, 2Department of Clinical Research, University of Bern, 3Department of Psychosomatic Medicine, Clinic Barmelweid, 4Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Switzerland, and 5Kinzigtal Hospital for Psychosomatic Medicine and Psychotherapy, Gengenbach, Germany
Objectives: In 2010, the American College of Rheumatology (ACR) proposed new criteria for the diagnosis of fibromyalgia (FM) in the context of objections to components of the criteria of 1990. The new criteria consider the Widespread Pain Index (WPI) and the Symptom Severity Score (SSS). This study evaluated the implications of the new diagnostic criteria for FM across other functional pain syndromes. Method: A cohort of 300 consecutive in-patients with functional pain syndromes underwent a diagnostic screen according to the ACR 2010 criteria. Additionally, systematic pain assessment including algometric and psychometric data was carried out. Results: Twenty-five patients (8.3%) had been diagnosed with FM according to the ACR 1990 criteria. Twenty-one of them (84%) also met the new ACR 2010 criteria. In total, 130 patients (43%) fulfilled the new ACR 2010 criteria. A comparison of new vs. old cases showed a high degree of conformity in most of the pain characteristics. The new FM cases, however, revealed a pronounced heterogeneity in the anatomical pain locations, including several types of localized pain syndromes. Furthermore, patients fulfilling the ACR 2010 FM criteria differed from those with other functional pain syndromes; they had increased pain sensitivity scores and increased psychometric values for depression, anxiety, and psychological distress (p < 0.01). Conclusions: FM according to the ACR 2010 criteria describes the ‘severe half’ of the spectrum of functional pain syndromes. By dropping the requirement of ‘generalized pain’, these criteria result in a blurring of the distinction between FM and more localized functional pain syndromes.
Much effort has been exerted for decades to determine the most accurate diagnostic criteria for fibromyalgia (FM). The difficulty in assigning this pain syndrome to a diagnostic category is due both to its complexity and to the fact that our understanding of the pathophysiology of this disorder is limited. Apart from generalized hyperalgesia (1), FM still lacks clear physical or laboratory features. The newly proposed criteria by the American College of Rheumatology (ACR) in 2010 are remarkable not only in their ability to define the diagnosis and assess the severity of the disease but also in the fact that no clinical findings are included in the definition criteria (2). Furthermore, the ACR 2010 criteria (2) differ from the ACR 1990 criteria (3) mainly in that they no longer include an assessment of tender points but make a diagnosis of FM exclusively on the basis of two symptom scores retrievable from the patient’s history. Niklaus Egloff, Department of General Internal Medicine, University Hospital, CH-3010 Bern, Switzerland. E-mail: [email protected] Accepted 17 January 2015
The Widespread Pain Index (WPI) in the 2010 criteria set quantifies the extent of somatic pain and makes an inventory of occurrence of pain in 19 defined body locations. In contrast to the ACR 1990 criteria, the WPI does not specify the overall anatomical distribution pattern of pain for diagnosis of FM, that is meeting the 1990 ‘widespread pain criterion’ (¼ axial pain, left- and right-sided pain, and pain in the upper and lower body segments) is no longer necessary (2). The Symptom Severity Score (SSS) contains the four items fatigue, non-restorative sleep, cognitive symptoms, and an item comprising a multiplicity of other concomitant symptoms. A score of 7 on the WPI and of 5 on the SSS or a WPI score of 3–6 and an SSS 9 is considered to adequately satisfy the diagnostic criteria. Validation analyses of the new assessment instruments so far have shown good consistency of the results obtained within populations of patients with FM (4, 5). However, a validation of (slightly modified) ACR criteria 2010 among related rheumatological disorders (e.g. inflammatory rheumatic conditions) in a large-scale study based on the US
© 2015 Informa Healthcare on license from Scandinavian Rheumatology Research Foundation DOI: 10.3109/03009742.2015.1010103
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National Data Bank for Rheumatic Diseases (NDB) produced somewhat questionable results (6, 7). It is as yet unclear whether the ACR 2010 criteria are sufficiently accurate to allow for a distinction between FM and other functional or neuropsychiatric pain syndromes (8), or between FM and disorders so far subsumed under the term ‘incomplete fibromyalgia syndrome’ (9). The primary aim of this study was to examine to what extent ACR 2010 FM criteria affect the clinical picture of FM and, more generally, that of functional pain syndromes. To this end, besides conventional pain parameters, we examined sociodemographic, algometric, and psychometric factors in relation to the WPI and the SSS. Our hypothesis was that applying the ACR 2010 FM criteria to patients with functional pain syndromes would result in an increase in the number of patients diagnosed with FM and also in greater heterogeneity of the clinical picture presented by these patients.
Method Patient recruitment During a 15-month period we collected data on 300 consecutive in-patients with a diagnosis of a functional pain syndrome at a tertiary university centre for multimodal pain therapy. The defining eligibility criterion for a functional pain syndrome was pain without any, or any sufficient, explanatory peripheral biomorphological correlate. The term comprises diagnoses such as FM, chronic tension headache, chronic temporomandibular joint disorder, chronic atypical facial pain, chronic low back pain, chronic atypical chest pain, the group of functional gastrointestinal pain disorders (e.g. irritable bowel syndrome, functional dyspepsia, and functional abdominal pain), and the group of chronic pelvic pain syndromes (e.g. chronic non-inflammatory prostatitis, painful bladder syndrome, and female urethral syndrome) (1). At the beginning of the study, all available charts including assessments by physicians or healthcare professionals as well as radiological or serologic data were thoroughly reviewed. If deemed necessary, further examinations to specify the diagnosis of the pain syndrome were performed. Physicians of the pain ward closely collaborate with consultants in related specialties (rheumatology, neurology, anaesthesiology, orthopaedic surgery). During their hospital stay, the diagnosis of pain in all 300 patients was carefully reviewed by the same members of the study team. If a patient’s pain problem was localized (¼ not congruent with the ‘widespread pain criterion from 1990’), there was no requirement to assess tender points. Irrespective of whether or not the patients met 1990 ACR criteria, all 300 patients were subsequently screened with the new 2010 ACR criteria. This resulted in the following subgroups of patients: patients meeting the ACR 1990 criteria (FM 1990), patients meeting the ACR 2010 criteria (FM 2010),
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patients meeting ACR 1990 plus 2010 criteria, and patients who did not meet either of the FM criteria. Medical history Patients were examined by internal medicine residents trained in Engel’s biopsychosocial interview method (10) and supervised by board-certified internists and psychiatrists trained in psychosomatic medicine, including pain medicine. The SSS was based on a tightly structured systematic interview in which data were collected on the medical history of the patient. Furthermore, a detailed inventory was taken of specific pain characteristics such as intensity, duration, type and dynamics of pain, factors modulating pain intensity, localization, concomitant complaints, secondary pain, and effect of analgesics administered. In the second, semi-structured part of the interview, demographic data and data on adverse life events were noted. The individualized, narrative exploration of adverse life events focused on five subject areas: major accidents, migration background, relational problems, stress at work, and adverse childhood experiences. The last of these were formulated according to the cohort study of Felliti et al (11). In total, 24 items of adverse life events were analysed (data not shown).
Pain drawings To ascertain the WPI score, patients were asked to draw their pain. Specifically, following a validated procedure as described previously (12), patients were instructed to mark all painful body areas on a body diagram. In evaluating the drawings, particular attention was given to quantifiable measures such as number of marks, length of the largest mark, and elements of axial symmetry. These three criteria have been validated as markers of a functional origin of pain (12). Examination of the drawings of patients with FM 2010 showed the following patterns of anatomical pain distribution: generalized pain syndrome (affecting all four quadrants), unilateral (affecting one half of the body only), axial-symmetric, but limited to head/trunk and upper part of the body, and localized pain syndromes (not symmetric, affecting at least one but at most two quadrants). Algometry The algometric method to detect hyperalgesia was carried out by means of a standardized and validated pressure pain provocation test (13). For this purpose, a standardized peg with a clamping force of exactly 10 N at an extension of 5 mm (Type Algopeg, size 78 10 mm, polypropylene and nickel) is applied on the finger and the earlobes for 10 s each. The patient indicates intensity of pain on a numerical rating scale (NRS) on which 0 stands
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for ‘no pain’ and 10 for ‘the most intense pain imaginable’. High pain ratings on the NRS correspond with high pain sensitivity and with low pain thresholds (13).
300 patients with functional pain syndrome
130 FM according to ACR 2010
Clinical examination of all patients included a thorough psychiatric work-up. Psychiatric comorbidities were assessed with a semistructured clinical interview according to ICD-10 criteria and validated by clinical observation over a period of more than 3 weeks of in-patient care. Furthermore, almost all patients underwent psychometric assessment using three validated and generally used instruments (German editions): the Hospital Anxiety and Depression Scale (HADS) is used to determine the level of anxiety and depression a patient experienced in the previous week (two scales with seven items each with a score 0–21) (14). The Brief Symptom Inventory (BSI) is a self-reported inventory with subscales to assess symptom groups concerning somatization, obsessive–compulsive symptoms, interpersonal sensitivity, depression, phobic anxiety, paranoia, and psychoticism (Global Severity Index: 0–3 points; Positive Symptom Total: 0–53 points; Positive Symptom Distress Index: 0–3 points) (15). The Perceived Stress Scale (PSS) is a widely used instrument for measuring non-specific perceived stress (14 items: 0–56 points) (16).
Statistical analysis For statistical analysis, we used SPSS 17 for Windows (SPSS Inc, Chicago, IL, USA). Normal distribution was tested with the Kolmogorov–Smirnoff test and if not fulfilled, non-parametric statistical analyses were used. We used descriptive statistics to compare patient groups across sociodemographic data, clinical symptoms, pain history, adverse life events, psychiatric comorbidity, and medications. Group comparisons for categorical variables used Pearson’s χ 2 test or Fisher’s exact test where appropriate. The Mann–Whitney test or an independent sample test was used for comparisons of continuous variables. Variables are expressed as percentages and medians (interquartile range). The level of significance was set at p < 0.05 (two-tailed). We used Spearman’s rho correlation coefficient to test for associations between the SSS, the WPI score, and the described psychosocial variables (HADS; BSI; PSS) as well as algometry data and baseline pain measurement. With regard to psychometric data, we used sum scores. To adjust for multiple comparisons, only pvalues < 0.003 were deemed to be statistically significant.
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Figure 1. Overview of the cohort of patients with functional pain syndromes including the subgroups with fibromyalgia (FM) according to the ACR 1990 and 2010 criteria.
distribution for the 300 patients with respect to WPI and SSS is shown in Figures 2 and 3, respectively. Of the 300 patients with functional pain syndromes investigated in this study, 25 (8.3%) met the ACR 1990 criteria for diagnosis of FM. Of these, 21 (84%) also fulfilled the ACR 2010 criteria. In total, 130 (43.3%) out of the cohort of 300 patients with functional pain syndromes met the new FM 2010 criteria. Twenty-one patients met both the 1990 and 2010 criteria for FM, 109 patients met only the 2010 and not the 1990 criteria. In the subgroup not meeting the ACR 1990 criteria (n ¼ 275), we found the following pain diagnoses and their combinations: chronic cervical pain syndromes; 60
Fibromyalgia according to ACR 1990, n = 25 Fibromyalgia according to ACR 2010, n = 109 Other functional pain syndromes, n = 168
50
40
30
20
10
0
Results
25 FM according to ACR 1990 21
109
Frequency
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Psychometry
0
1
2
3
4
5
6 7 SSS
8
9 10 11 12
General patient characteristics Figure 1 gives a quantitative overview of the patient population, including subgroups. The frequency
Figure 2. Frequency distribution in the total cohort of 300 patients with functional pain syndromes and fibromyalgia (FM) in relation to the Symptom Severity Score (SSS).
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45 40
Fibromyalgia according to ACR 1990, n = 25 Fibromyalgia according to ACR 2010, n = 109 Other functional pain syndromes, n = 168
35
Frequency
30 25
An analysis of the pain distribution pattern in patients according to the ACR 2010 criteria showed that less than half of all patients (46%) suffered from pain in all four quadrants. Whereas 10.4% of FM 2010 patients suffered from unilateral pain syndromes, in 9.6% pain was limited to the head and trunk or to the upper part of the body; 10.4% of FM 2010 patients had local pain syndromes affecting just one or two quadrants. The remainder showed other forms of ‘incomplete’ distribution patterns.
20 15
How to distinguish between FM 2010 and the spectrum of functional pain disorders as a whole
10 5
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0
0 1 2 3 4 5 6 7 8 9 1011121314151617181920 WPI
Figure 3. Frequency distribution in the total cohort of 300 patients with functional pain syndromes and fibromyalgia (FM) in relation to Widespread Pain Index (WPI).
atypical chronic limb syndromes; functional hemisided or quadrantomal pain syndromes; chronic chest, trunk, chest, or low back pain; chronic tension headache; chronic temporomandibular disorder; chronic atypical facial pain syndrome; irritable bowel syndrome; chronic abdominal pain and chronic pelvic pain syndromes. One hundred and seventy patients (56.7%) did not meet either the 1990 or the 2010 ACR criteria. Two patients in this group were excluded from further analysis because of insufficient data so that the group comparison was performed with 168 patients without a diagnosis of FM 2010.
Similarities and differences between FM 1990 and FM 2010 Table 1 shows the group comparison of the 25 patients with FM 1990 and the 109 patients who met only the ACR 2010 criteria. No differences between the two groups were seen with respect to pain perception in tissues (mainly deep pain sensation), dominant pain quality (burning, stabbing, dragging pain, etc.), average pain duration, pain dynamics, and factors modulating pain as well as the effects of medication and the algometric assessment of pain sensitivity. The groups also did not differ in associated somatic complaints, extent of psychiatric comorbidities, level of stress, and adverse life events profile. In the group diagnosed according to the ACR 2010 criteria, there were significantly more patients with post-traumatic stress disorder (p ¼ 0.04), a history of accidents (p ¼ 0.03), and a history of migration background (p ¼ 0.02). The FM 2010 group showed higher average values of the SSS (p ¼ 0.03). By contrast, the group diagnosed with FM 1990 criteria had an increased WPI score (p ¼ 0.03).
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Table 2 shows a group comparison between all 130 patients meeting the ACR 2010 criteria (including the 21 patients also fulfilling the ACR 1990 criteria) and the 168 remaining patients with functional pain syndromes without a diagnosis of FM. The group with FM 2010 could be distinguished from the comparator group by significantly higher WPI and SSS scores (p < 0.001) and by increased pain levels (p < 0.001). Pain sensitivity, as assessed by algometry, also showed significantly higher levels in the FM group (middle finger: p ¼ 0.007, earlobe: p ¼ 0.003). All three functional criteria of pain drawings (i.e. number of marks, length of the largest mark, and elements of axial symmetry) showed significantly increased values in the FM 2010 group (p < 0.001). In four out of nine examined cases of associated somatic complaints, FM 2010 patients on average showed significantly more often symptoms (insomnia, dizziness, tension headache, atypical chest pain). FM 2010 patients did not differ from patients with other functional pain syndromes in age, gender distribution, pain localization in tissues (mainly deep pain), quality of pain (burning, stabbing, dragging pain, etc.), pain duration, and effects of medication. As far as adverse life events are concerned, the FM 2010 group showed a higher rate of both partner conflicts (p ¼ 0.03) and migration background (p ¼ 0.01). With regard to psychiatric co-diagnoses, the comorbidity rate of depression was significantly increased in the FM 2010 group compared with the group diagnosed with functional pain syndromes without FM (p < 0.001). In addition, a difference in incidence was noted with regard to post-traumatic stress disorders (p ¼ 0.03). The FM 2010 group had significantly higher scores in all assessed psychiatric comorbidity tests (HADS depression, HADS anxiety, and BSI) and also in stress exposure (p < 0.01).
Correlation of the WPI and the SSS Table 3 shows the correlation ratios of the WPI and the SSS with other investigated continuous indicators.
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Table 1. Fibromyalgia (FM) according to ACR 2010 criteria vs. ACR 1990 criteria.
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Variable Sex (male) Age (years) WPI SSS Pain duration (months) Pain intensity (NRS) Pain quality Stabbing Burning Pinching Pain dynamics Constant/with pain-free intervals Pain modulation Increase on mechanical stress Increase on psychological stress and nervousness Relief on relaxation Relief on physiotherapy Relief on application of heat Algometry Pain test on middle finger (NRS) Pain test on earlobe (NRS) Pain drawing Number of marks Length of longest mark Axial symmetry properties Concomitant complaints Insomnia Formication Nausea Dizziness Tension headache Irritable bowel syndrome Chronic genitourinary complaints Atypical chest pain Atypical facial pain Adverse life events Major accident event Migration background (first generation) Long-standing partner conflicts Adverse childhood experience Persistent overwork on the job Concomitant psychiatric diagnosis Post-traumatic stress disorder Depression Anxiety disorder Psychometry (SD) BSI – Total score HADS – Depression HADS – Anxiety PSS
FM according to ACR 2010 criteria (n ¼ 109)
FM according to ACR 1990 criteria (n ¼ 25)
p-value
Effect size
47.7 48 (43–54) 7 (5–9) 9 (8–10) 60 (18–120) 75 (6–8)
4.0 51 (48–57) 9 (6–13) 8 (7–9) 84 (21–162) 7 (6 –9)
< 0.001*** 0.19 0.03* 0.03* 0.52 0.99
1.11 0.29 0.46 0.46 0.06 0.01
28.0 20.0 17.2
33.3 33.3 20.8
0.79 0.16 0.68
0.06 0.13 0.04
86.4/13.6
91.9/8.7
0.52
0.06
72.2 33.3
76.0 36.0
0.70 0.80
0.03 0.02
17.6 33.3 26.9 79.3 4 (1–6) 8.5 (6–11) 89.9 11 (8–17) 43.5 (23–65) 75.5
24.0 24.0 20.0 76 4.5 (1–8) 9 (6–11) 80.0 15.5 (8–23) 38.0 (15–73) 90.0
0.46 0.37 0.48
0.06 0.28 0.06
0.32 0.76
0.25 0.08
0.16 0.66 0.15
0.43 0.02 0.13
53.2 16.0 11.3 17.9 27.5 9.2 8.3 16.5 5.5
60.0 16.7 8.3 12.5 16.0 20.0 0.0 8.0 8.0
0.54 0.94 0.67 0.52 0.23 0.12 0.14 0.28 0.64
0.05 0.09 0.04 0.06 0.10 0.13 0.13 0.09 0.04
56.0 69.7
32.0 44.0
0.03* 0.02*
0.19 0.21
52.3 45.9 59.6
64.0 56.0 76.0
0.29 0.36 0.13
0.09 0.08 0.13
22.0 86.2 19.3
4.0 88.0 28.0
0.04* 0.82 0.33
0.18 0.02 0.08
1.01 (0.60–1.00) 11.0 (5.0–14.0) 8.0 (4.0–15.0) 26.5 (18–34)
0.94 0.92 0.08 0.42
0.02 0.07 0.40 0.22
1.10 (0.70–1.00) 10 (7–15) 11 (8–14) 29 (24–40)
ACR, American College of Rheumatology; WPI, Widespread Pain Index; SSS, Symptom Severity Score; NRS, Numerical Rating Scale; BSI, Brief Symptom Inventory; HADS, Hospital Anxiety and Depression Scale; PSS, Perceived Stress Scale. Values given as percentage, mean standard deviation, or median (interquartile range).
In absolute values, the WPI score showed the greatest correlation with the finger algometric data (r ¼ 0.18; p < 0.001), whereas the SSS correlated greatest with psychometric BSI measure (r ¼ 0.39; p < 0.001), which was the same for the combined WPI and SSS score (r ¼ 0.28; p < 0.001). All correlation coefficients were positive,
confirming the assumption of a direct relationship between psychological burden and pain symptoms as well as the symptom severity index. Although effect sizes were only small to medium, most of the correlation coefficients remained significant after controlling for multiple comparisons.
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Table 2. Pain properties of fibromyalgia (FM) according to ACR 2010 criteria vs. other functional pain syndromes.
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Variable Sex (male) Age (years) WPI SSS Pain duration (months) Pain intensity (NRS) Pain quality Stabbing Burning Pinching Pain dynamics Constant/with pain-free intervals Pain modulation Increase on mechanical stress Increase on psychological stress and nervousness Relief on relaxation Relief on physiotherapy Relief on application of heat Algometry Pain test on middle finger (NRS) Pain test on earlobe (NRS) Pain drawing Number of marks Length of longest mark Axial symmetry properties Concomitant complaints Insomnia Formication Nausea Dizziness Tension headache Irritable bowel syndrome Chronic genitourinary complaints Atypical chest pain Atypical facial pain Adverse life events Major accident event Migration background (first generation) Long-standing partner conflicts Adverse childhood experience Persistent overwork on the job Concomitant psychiatric diagnosis Post-traumatic stress disorder Depression Anxiety disorder Psychometry (SD) BSI – Total score HADS – Depression HADS – Anxiety PSS
FM according to ACR 2010 criteria (n ¼ 130)
Other functional pain syndromes (n ¼ 168)
p-value
Effect size
41.5 49 (43–55) 8 (5–10) 9 (8–10) 60 (18–130) 7.5 (6–9)
48.8 48 (39–57) 3 (1–5) 6 (4–7) 53 (15–130) 6.5 (5–8)
0.20 0.52 < 0.001*** < 0.001*** 0.33 < 0.001***
0.01 0.08 1.69 1.45 0.01 0.48
30.0 24.2 17.6
33.1 28.2 15.3
87.7/12.3
70.3/29.7
73.6 34.1
0.63 0.52 0.72
0.10 0.10 0.05
0.002***
0.21
72.9 21.1
0.75 0.03*
0.04 0.15
19.4 31.8 25.6 79.3 4.08 2.96 7.94 3.04 88.5 12 (8–18) 45 (23–66) 77.4
18.6 32.3 22.8 63.3 3.01 2.47 6.87 3.09 77.4 6 (3–9) 20 (10–36) 48.8
0.78 0.86 0.59
0.05 0.03 0.06
0.007** 0.003**
0.40 0.35
< 0.001*** < 0.001*** < 0.001***
0.61 0.89 0.27
55.4 16.7 10.3 16.7 26.2 10.8 8.5 15.4 6.2
42.3 11.4 11.4 6.6 14.3 7.7 7.1 5.4 5.4
0.03* 0.37 0.84 0.02* 0.02* 0.60 0.84 0.01* 0.90
0.15 0.08 0.03 0.16 0.16 0.06 0.03 0.17 0.16
51.5 66.2
47.6 48.2
0.30 0.01**
0.09 0.18
53.8 47.7 62.3
41.1 56.5 59.5
0.03* 0.32 0.47
0.04 0.10 0.03
19.2 86.9 21.5
8.9 63.7 19.0
0.03* < 0.001*** 0.68
15 0.26 0.05
< 0.001*** < 0.001*** < 0.001*** < 0.01**
0.61 0.51 0.50 0.44
1.1 (1–2) 10 (7–15) 11 (8–14) 29 (24–38)
0.7 0 (0.4–1) 8 (4–11) 8 (5–12) 27 (17–32)
ACR, American College of Rheumatology; WPI, Widespread Pain Index; SSS, Symptom Severity Score; NRS, Numerical Rating Scale; BSI, Brief Symptom Inventory; HADS, Hospital Anxiety and Depression Scale; PSS, Perceived Stress Scale. Values given as percentage, mean standard deviation, or median (interquartile range).
Discussion FM 2010, the ‘severe half’ of the functional pain syndromes Of patients who met the FM 1990 criteria (n ¼ 25), 84% also fulfilled the 2010 criteria. Thus, there is undoubtedly
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high internal congruence of pain characteristics between FM 1990 and FM 2010. These data are congruent with data from other studies (4, 5). With respect to the whole group of functional pain syndromes, Figures 2 and 3 show that FM (1990 and
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Table 3. Spearman’s rho correlation of the WPI and SSS with other continuous variables in functional pain syndromes.
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WPI/Finger algometry WPI/Earlobe algometry WPI/Baseline pain SSS/HADS SSS/HADS – Anxiety SSS/HADS – Depression SSS/BSI SSS/PSS WPIþSSS/Finger algometry WPIþSSS/Earlobe algometry WPIþSSS/Baseline pain WPIþSSS/HADS WPIþSSS/HADS – Anxiety WPIþSSS/HADS – Depression WPIþSSS/BSI WPIþSSS/PSS
r
p
0.25 0.22 0.22 0.33 0.20 0.31 0.39 0.24 0.18 0.18 0.23 0.27 0.26 0.24 0.28 0.21
< 0.001*** 0.001*** < 0.001*** < 0.001*** < 0.001*** < 0.001*** < 0.001*** < 0.01 0.01 0.01 < 0.001*** < 0.001*** < 0.001*** < 0.001*** < 0.001*** < 0.01
WPI, Widespread Pain Index; SSS, Symptom Severity Score; HADS, Hospital Anxiety and Depression Scale; BSI, Brief Symptom Inventory; PSS, Perceived Stress Scale. ** < 0.01; ** < 0.001.
2010) is seamlessly embedded in this spectrum. With regard to SSS and WPI, the ACR 2010 criteria approximately select the right-hand half of the bellshaped curve within this spectrum. This almost Gaussian frequency distribution does not show any twin-peak pattern, giving no indication of a real discriminant diagnostic function of the WPI and SSS in this spectrum. The ‘more severe half’ of the spectrum of all functional pain syndromes is labelled as FM with the new ACR 2010 criteria.
Increase in FM diagnoses according to the ACR 2010 criteria Among the 300 patients with functional pain disorders, 43.3% fulfilled the FM 2010 criteria. The phenotype of FM 1990 in the same group was diagnosed in only 8%. As a potential methodological bias, it should be pointed out that all 300 patients were systematically screened with the ACR 2010 criteria, whereas the tender point test was carried out only in those patients with clinical suspicion of FM 1990 based on the ‘widespread pain criterion’. Nonetheless, the basic point made remains the same: depending on the point of reference chosen (ACR 1990 criteria or ACR 2010 criteria), our data suggest that, under the old diagnostic system, many FM patients were ‘missed’ (false negative); the systematic use of the ACR 2010 criteria, by contrast, would result in many patients being diagnosed with FM who would not have been diagnosed with this condition before (overdiagnosis).
Heterogeneous pattern of the anatomical distribution of FM 2010 So far, FM (according to the ACR 1990 criteria) has been considered the ‘whole-body variant’ of functional pain syndromes (3). The ACR 2010 criteria yield a more heterogeneous picture as far as the anatomical pattern of distribution is concerned. This is because the ‘widespread pain criterion’ used in the 1990 definition of FM (axial pain, left- and right-sided pain, and pain in the upper and lower body segments) is no longer applied. Meanwhile, the ACR criteria 2010 follow a ‘double logic’: On the one hand, the probability of diagnosing FM 2010 appears to be greater the more a pain syndrome is multifocal in nature (high WPI score); on the other hand, a mere shoulder-arm syndrome could be labelled as FM too, if the SSS is sufficiently high (e.g. in depressive patients). With regard to these ‘new’ cases of FM with strictly localized pain (10.4% in our FM cohort), the question arises as to how the 2010 criteria are able to differentiate FM from, for example, myofascial pain syndromes (17). In addition, functional pain syndromes with hemibody distribution (in our FM 2010 cohort a further 10.4%) were classified as FM, although they can otherwise be characterized in a clearly more specific way (18–20). In sum, the ACR 2010 criteria do not help to differentiate ‘incomplete forms of FM’ from other forms of chronic widespread pain but instead result in a mixing up of terms (9). For this reason, this aspect of the ACR 2010 criteria was criticized for being ‘inconsistent’ and causing a ‘dilution’ of the former concept of FM 1990 (6).
Symptom scores never provide a diagnosis Originally, the declared aim of the ACR 2010 was ‘to develop simple, practical criteria for the clinical diagnosis of fibromyalgia’ (3). Contrary to the Budapest criteria for complex regional pain syndromes (21), the ACR 2010 criteria ‘diagnose’ FM solely on the basis of symptoms mentioned in the patient history; that is they do not take into account criteria that can be clinically examined. This methodological approach was subject to criticism from the very beginning (6, 8, 9). Regarding the ‘modified’ ACR 2010 criteria, the ACR author team went even a step further in that patients could self-declare and score their own symptoms (this even eliminated the need for diagnostic medical interviews). This approach results in a failure to provide a diagnostic instrument fit for clinical purpose; according to a study by Wolfe et al (7), as few as 60% of patients with FM 1990 as an entry diagnosis fulfilled the modified ACR 2010 criteria, while 37% of patients with systemic lupus erythematosus (SLE) also met the new diagnostic criteria of FM 2010. Furthermore, the ACR 2010 criteria did not help in differentiating false diagnoses from actual double diagnoses (7). The resulting loss of specificity and differentiation has not remained unnoticed (6, 9).
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There is no way around a clinical diagnosis of FM Both the above-mentioned study by Wolfe et al (7) and our own data raise a fundamental question of methodology; namely, to what extent are symptom scores typical of a disease suitable as a diagnostic instrument? For instance, no specialist in internal medicine would be likely to confuse the New York Heart Association (NYHA) criteria for quantifying dyspnoea in heart failure with the diagnosis of the underlying cardiopathy. In other words, the symptom scores used for monitoring progression (e.g. in studies) are not the type of instrument needed or suitable for the clinical diagnosis of diseases. As it did not seem clear from the outset that the ACR 2010 criteria would prove to be suitable for clinical diagnosis of FM in primary and speciality care settings, the authors of the ACR 2010 criteria added a quasicautionary comment: ‘It is important to exclude other causes of chronic widespread pain or identify potential coexisting rheumatic diseases’ (2). This diagnosis by exclusion becomes problematic because FM is often diagnosed concurrently with a variety of other diseases (1, 7, 22). If FM becomes a diagnosis by exclusion, it means that the ACR 2010 criteria failed to include sufficient entity-specific characteristics. In search of entity-specific criteria, Yunus (1) already suggested several years ago that generalized hyperalgesia (central sensitivity) is the core pathophysiological element of FM and overlapping disorders. Along with numerous previous studies (23– 26), our algometric data confirm that the feature of hyperalgesia is a crucial characteristic of this pain disorder. In assessing tender points according to the ACR 1990 criteria, the clinical screening automatically focused on generalized allodynia/hyperalgesia. Even if the majority of experts today agree that a painstaking interpretation and count of tender points misses the intended target (2), there are still some valid concerns that totally abandoning the tender point concept would imply abandoning the strategy of screening for generalized hyperalgesia. It would seem that dropping the tender point concept is not only the main advantage of the ACR 2010 criteria but also their greatest drawback. We do not suggest reinstating the old concept of tender points; instead, we recommend that the clinical finding of generalized hyperalgesia should be reintegrated and operationalized as a standardized algometric procedure. If we keep the focus in FM on the aspect of generalized hyperalgesia, it will automatically become possible to delimit FM against the whole puzzle of localized pain syndromes.
Mental symptoms in FM An improvement in the ACR 2010 criteria worth mentioning is the fact that the SSS now incorporates mental symptoms, which make it clear that FM is not just one among several musculoskeletal diseases but a complex processing disorder of pain and stress (27–29). The
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influence of chronic stress on increased pain perception should be the centre of future FM research and therapy (30). Several studies using animal models help to untangle the mechanisms leading to stress-induced hyperalgesia both at the central and peripheral level (31–34). Like many earlier studies (35–38), our data, too, confirm the existence of a correlation between FM and psychosocial stressors: about 60% of our patients complained of being persistently overworked in their jobs. There is clinical manifestation of depressive disorder in more than 85% concomitantly with their pain condition. Our investigations provide proof of arithmetic correlation between the SSS and the psychometrically assessed burden imposed by depression and stress (p < 0.001). With regard to its therapeutic consequences, the question arises as to whether directly assessing the burden of stress and depression in FM might not be more meaningful than checking 40 confusing bodily symptoms as required by the SSS. To summarize, the ACR 2010 criteria clearly alter the case definition of FM. By omitting the requirement of ‘generalized pain’, the distinction between the FM and more localized functional pain syndromes is blurred. Furthermore, by dropping the tender point assessment, the ACR 2010 criteria omit examination of the distinctive ‘hyperalgesia aspect’ of FM. The ACR 2010 symptom checklists are no doubt very simple to use, but as a matter of principle, a new research-based concept of FM should include rather than avoid pathophysiological findings. There is a quote attributed to Albert Einstein: ‘Everything should be made as simple as possible, but not simpler’. It remains to be hoped that these issues will be taken into consideration in the ongoing discussion on FM criteria. Acknowledgements We thank JP Geri, A Kocher, and R Csordas-Iyer for editorial assistance.
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Implications of the new fibromyalgia criteria 7. Wolfe F, Clauw DJ, Fitzcharles MA, Goldenberg DL, Häuser W, Katz RS, et al. Fibromyalgia criteria and severity scales for clinical and epidemiological studies: a modification of the ACR preliminary diagnostic criteria for fibromyalgia. J Rheumatol 2011;38:1113–22. 8. Vanderschueren S, Van Wambeke P, Morlion B. Fibromyalgia: do not give up the tender point count too easily: comment on the article by Wolfe et al. Arthritis Care Res 2010;62:1675. 9. Yunus MB, Aldag JC. The concept of incomplete fibromyalgia syndrome: comparison of incomplete fibromyalgia syndrome with fibromyalgia syndrome by 1990 ACR classification criteria and its implications for newer criteria and clinical practice. J Clin Rheumatol 2012;18:71–5. 10. Engel GL, Morgan WL. The clinical approach to the patient. Philadelphia: WB Saunders Co, 1969. 11. Felitti VJ, Anda RF, Nordenberg D, Williamson DF, Spitz AM, Edwards V, et al. Relationship of child abuse and household dysfunction to many of the leading causes of death in adults. Am J Prev Med 1998;14:245–58. 12. Egloff N, Cámara RJ, von Känel R, Klingler N, Marti E, Ferrari ML. Pain drawings in somatoform-functional pain. BMC Musculoskelet Disord 2012;13:257. 13. Egloff N, Klingler N, von Känel R, Cámara RJ, Curatolo M, Wegmann B, et al. Algometry with a clothes peg compared to an electronic pressure algometer: a randomized cross-sectional study in pain patients. BMC Musculoskelet Disord 2011;12:174. 14. Bjelland I, Dahl AA, Haug TT, Neckelmann D. The validity of the Hospital Anxiety and Depression Scale. An updated literature review. J Psychosom Res 2002:52:69–77. 15. Derogatis LR, Melisaratos N.The Brief Symptom Inventory: an introductory report. Psychol Med 1983;13:595–605. 16. Cohen S, Kamarck T, Mermelstein R. A global measure of perceived stress. J Health Soc Behav 1983;24:385–96. 17. Thompson EN. Diagnostic criteria for fibromyalgia: comment on the article by Wolfe et al. Arthritis Care Res 2010;62:1674. 18. Egloff N, Maecker F, Stauber S, Sabbioni M, Tunklova L, von Känel R. Nondermatomal somatosensory deficits in chronic pain patients: are they really hysterical? Pain 2012;153:1847–52. 19. Egloff N, Sabbioni ME, Salathé C, Wiest R, Juengling FD. Nondermatomal somatosensory deficits in patients with chronic pain disorder: clinical findings and hypometabolic pattern in FDG–PET. Pain 2009;145:252–8. 20. Mailis-Gagnon A, Giannoylis I, Downar J, Kwan CL, Mikulis DJ, Crawley AP, et al. Altered central somatosensory processing in chronic pain patients with ‘hysterical’ anesthesia. Neurology 2003;60:1501–7. 21. Harden RN, Bruehl S, Perez R, Birklein F, Marinus J, Maihofner C, et al. Validation of proposed diagnostic criteria (the ‘Budapest criteria’) for complex regional pain syndrome. Pain 2010;150:268–74. 22. Wessely S, Nimnuan C, Sharpe M. Functional somatic syndromes: one or many? Lancet 1999;354:936–9.
9 23. 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;48:1420–9. 24. Graven-Nielsen T, Aspegren Petzke F, Clauw DJ, Ambrose K, Khine A, Gracely RH. Increased pain sensitivity in fibromyalgia: effects of stimulus type and mode of presentation. Pain 2003;105:403–13. 25. Lautenbacher S, Rollman GB, McCain GA. Multi-method assessment of experimental and clinical pain in patients with fibromyalgia. Pain 1994;59:45–53. 26. Sorensen J, Graven-Nielsen T, Henriksson KG, Bengtsson M, Arendt-Nielsen L. Hyperexcitability in fibromyalgia. J Rheumatol 1998;25:152–5. 27. Egle UT, Ecker-Egle ML, Nickel R. [Fibromyalgia-Syndrom – eine Stressverarbeitungsstörung], in German. Schweiz Arch Neurol Psych 2011;162:326–37. 28. Egle UT, Hardt J, Nickel R, Kappis B, Hoffmann SO. Early stress and its long-term effects on health – state of the art and implications for future research. Z Psychosom Med Psychother 2002;48:411–34. 29. Imbierowicz K, Egle UT. Childhood adversities in patients with fibromyalgia and somatoform pain disorders. Eur J Pain 2003;7:113–19. 30. Jennings EM, Okine BN, Roche M, Finn DP. Stress-induced hyperalgesia. Prog Neurobiol 2014;121:1–18. 31. Alvarez P, Paul G, Green PG, Levine JD. Stress in the adult rat exacerbates muscle pain induced by early-life stress. Biol Psychiatry 2013;74:688–95. 32. Green PG, Alvarez P, Gear RW, Mendoza D, Levine JD. Further validation of a model of fibromyalgia syndrome in the rat. J Pain 2011;12:811–18. 33. Green PG, Chen X, Alvarez P, Ferrari LF, Levine JD. Early-life stress produces muscle hyperalgesia and nociceptor sensitization in the adult rat. Pain 2011;152:2549–56. 34. Khasar SG, Burkham J, Dina OA, Brown AS, Bogen O, AlessandriHaber N, et al. Stress induces a switch of intracellular signaling in sensory neurons in a model of generalized pain. J Neurosci 2008;28:5721–30. 35. Anderberg UM, Marteinsdottir I, Theorell T, Von Korring L. The impact of life events in female patients with fibromyalgia and in female healthy controls. Eur Psychiatry 2000;15: 295–301. 36. Dailey PA, Bishop GD, Russel JL, Fletcher EM. Psychosocial stress and fibromyalgia/fibrositis syndrome. J Rheumatol 1990; 17:1380–5. 37. Van Houdenhove B, Egle UT, Luyten P. The role of life stress in fibromyalgia. Curr Rheumatol Rep 2005;7:365–70. 38. Björnsdóttir SV1, Jónsson SH, Valdimarsdóttir UA. Mental health indicators and quality of life among individuals with musculoskeletal chronic pain: a nationwide study in Iceland. Scand J Rheumatol 2014;43:419–23.
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Implications of proposed fibromyalgia criteria across other functional pain syndromes N Egloff, R von Känel, V Müller, UT Egle, G Kokinogenis, S Lederbogen, B Durrer & S Stauber To cite this article: N Egloff, R von Känel, V Müller, UT Egle, G Kokinogenis, S Lederbogen, B Durrer & S Stauber (2015): Implications of proposed fibromyalgia criteria across other functional pain syndromes, Scandinavian Journal of Rheumatology To link to this article: http://dx.doi.org/10.3109/03009742.2015.1010103
Published online: 16 Jun 2015.
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Date: 16 September 2015, At: 07:11
Scand J Rheumatol 2015;iFirst article:1–9
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Implications of proposed fibromyalgia criteria across other functional pain syndromes N Egloff1,2, R von Känel3,4, V Müller1, UT Egle5, G Kokinogenis1,2, S Lederbogen1, B Durrer1, S Stauber1 1
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Department of General Internal Medicine, Division of Psychosomatic Medicine, Inselspital, Bern University Hospital, and University of Bern, 2Department of Clinical Research, University of Bern, 3Department of Psychosomatic Medicine, Clinic Barmelweid, 4Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Switzerland, and 5Kinzigtal Hospital for Psychosomatic Medicine and Psychotherapy, Gengenbach, Germany
Objectives: In 2010, the American College of Rheumatology (ACR) proposed new criteria for the diagnosis of fibromyalgia (FM) in the context of objections to components of the criteria of 1990. The new criteria consider the Widespread Pain Index (WPI) and the Symptom Severity Score (SSS). This study evaluated the implications of the new diagnostic criteria for FM across other functional pain syndromes. Method: A cohort of 300 consecutive in-patients with functional pain syndromes underwent a diagnostic screen according to the ACR 2010 criteria. Additionally, systematic pain assessment including algometric and psychometric data was carried out. Results: Twenty-five patients (8.3%) had been diagnosed with FM according to the ACR 1990 criteria. Twenty-one of them (84%) also met the new ACR 2010 criteria. In total, 130 patients (43%) fulfilled the new ACR 2010 criteria. A comparison of new vs. old cases showed a high degree of conformity in most of the pain characteristics. The new FM cases, however, revealed a pronounced heterogeneity in the anatomical pain locations, including several types of localized pain syndromes. Furthermore, patients fulfilling the ACR 2010 FM criteria differed from those with other functional pain syndromes; they had increased pain sensitivity scores and increased psychometric values for depression, anxiety, and psychological distress (p < 0.01). Conclusions: FM according to the ACR 2010 criteria describes the ‘severe half’ of the spectrum of functional pain syndromes. By dropping the requirement of ‘generalized pain’, these criteria result in a blurring of the distinction between FM and more localized functional pain syndromes.
Much effort has been exerted for decades to determine the most accurate diagnostic criteria for fibromyalgia (FM). The difficulty in assigning this pain syndrome to a diagnostic category is due both to its complexity and to the fact that our understanding of the pathophysiology of this disorder is limited. Apart from generalized hyperalgesia (1), FM still lacks clear physical or laboratory features. The newly proposed criteria by the American College of Rheumatology (ACR) in 2010 are remarkable not only in their ability to define the diagnosis and assess the severity of the disease but also in the fact that no clinical findings are included in the definition criteria (2). Furthermore, the ACR 2010 criteria (2) differ from the ACR 1990 criteria (3) mainly in that they no longer include an assessment of tender points but make a diagnosis of FM exclusively on the basis of two symptom scores retrievable from the patient’s history. Niklaus Egloff, Department of General Internal Medicine, University Hospital, CH-3010 Bern, Switzerland. E-mail: [email protected] Accepted 17 January 2015
The Widespread Pain Index (WPI) in the 2010 criteria set quantifies the extent of somatic pain and makes an inventory of occurrence of pain in 19 defined body locations. In contrast to the ACR 1990 criteria, the WPI does not specify the overall anatomical distribution pattern of pain for diagnosis of FM, that is meeting the 1990 ‘widespread pain criterion’ (¼ axial pain, left- and right-sided pain, and pain in the upper and lower body segments) is no longer necessary (2). The Symptom Severity Score (SSS) contains the four items fatigue, non-restorative sleep, cognitive symptoms, and an item comprising a multiplicity of other concomitant symptoms. A score of 7 on the WPI and of 5 on the SSS or a WPI score of 3–6 and an SSS 9 is considered to adequately satisfy the diagnostic criteria. Validation analyses of the new assessment instruments so far have shown good consistency of the results obtained within populations of patients with FM (4, 5). However, a validation of (slightly modified) ACR criteria 2010 among related rheumatological disorders (e.g. inflammatory rheumatic conditions) in a large-scale study based on the US
© 2015 Informa Healthcare on license from Scandinavian Rheumatology Research Foundation DOI: 10.3109/03009742.2015.1010103
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National Data Bank for Rheumatic Diseases (NDB) produced somewhat questionable results (6, 7). It is as yet unclear whether the ACR 2010 criteria are sufficiently accurate to allow for a distinction between FM and other functional or neuropsychiatric pain syndromes (8), or between FM and disorders so far subsumed under the term ‘incomplete fibromyalgia syndrome’ (9). The primary aim of this study was to examine to what extent ACR 2010 FM criteria affect the clinical picture of FM and, more generally, that of functional pain syndromes. To this end, besides conventional pain parameters, we examined sociodemographic, algometric, and psychometric factors in relation to the WPI and the SSS. Our hypothesis was that applying the ACR 2010 FM criteria to patients with functional pain syndromes would result in an increase in the number of patients diagnosed with FM and also in greater heterogeneity of the clinical picture presented by these patients.
Method Patient recruitment During a 15-month period we collected data on 300 consecutive in-patients with a diagnosis of a functional pain syndrome at a tertiary university centre for multimodal pain therapy. The defining eligibility criterion for a functional pain syndrome was pain without any, or any sufficient, explanatory peripheral biomorphological correlate. The term comprises diagnoses such as FM, chronic tension headache, chronic temporomandibular joint disorder, chronic atypical facial pain, chronic low back pain, chronic atypical chest pain, the group of functional gastrointestinal pain disorders (e.g. irritable bowel syndrome, functional dyspepsia, and functional abdominal pain), and the group of chronic pelvic pain syndromes (e.g. chronic non-inflammatory prostatitis, painful bladder syndrome, and female urethral syndrome) (1). At the beginning of the study, all available charts including assessments by physicians or healthcare professionals as well as radiological or serologic data were thoroughly reviewed. If deemed necessary, further examinations to specify the diagnosis of the pain syndrome were performed. Physicians of the pain ward closely collaborate with consultants in related specialties (rheumatology, neurology, anaesthesiology, orthopaedic surgery). During their hospital stay, the diagnosis of pain in all 300 patients was carefully reviewed by the same members of the study team. If a patient’s pain problem was localized (¼ not congruent with the ‘widespread pain criterion from 1990’), there was no requirement to assess tender points. Irrespective of whether or not the patients met 1990 ACR criteria, all 300 patients were subsequently screened with the new 2010 ACR criteria. This resulted in the following subgroups of patients: patients meeting the ACR 1990 criteria (FM 1990), patients meeting the ACR 2010 criteria (FM 2010),
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patients meeting ACR 1990 plus 2010 criteria, and patients who did not meet either of the FM criteria. Medical history Patients were examined by internal medicine residents trained in Engel’s biopsychosocial interview method (10) and supervised by board-certified internists and psychiatrists trained in psychosomatic medicine, including pain medicine. The SSS was based on a tightly structured systematic interview in which data were collected on the medical history of the patient. Furthermore, a detailed inventory was taken of specific pain characteristics such as intensity, duration, type and dynamics of pain, factors modulating pain intensity, localization, concomitant complaints, secondary pain, and effect of analgesics administered. In the second, semi-structured part of the interview, demographic data and data on adverse life events were noted. The individualized, narrative exploration of adverse life events focused on five subject areas: major accidents, migration background, relational problems, stress at work, and adverse childhood experiences. The last of these were formulated according to the cohort study of Felliti et al (11). In total, 24 items of adverse life events were analysed (data not shown).
Pain drawings To ascertain the WPI score, patients were asked to draw their pain. Specifically, following a validated procedure as described previously (12), patients were instructed to mark all painful body areas on a body diagram. In evaluating the drawings, particular attention was given to quantifiable measures such as number of marks, length of the largest mark, and elements of axial symmetry. These three criteria have been validated as markers of a functional origin of pain (12). Examination of the drawings of patients with FM 2010 showed the following patterns of anatomical pain distribution: generalized pain syndrome (affecting all four quadrants), unilateral (affecting one half of the body only), axial-symmetric, but limited to head/trunk and upper part of the body, and localized pain syndromes (not symmetric, affecting at least one but at most two quadrants). Algometry The algometric method to detect hyperalgesia was carried out by means of a standardized and validated pressure pain provocation test (13). For this purpose, a standardized peg with a clamping force of exactly 10 N at an extension of 5 mm (Type Algopeg, size 78 10 mm, polypropylene and nickel) is applied on the finger and the earlobes for 10 s each. The patient indicates intensity of pain on a numerical rating scale (NRS) on which 0 stands
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for ‘no pain’ and 10 for ‘the most intense pain imaginable’. High pain ratings on the NRS correspond with high pain sensitivity and with low pain thresholds (13).
300 patients with functional pain syndrome
130 FM according to ACR 2010
Clinical examination of all patients included a thorough psychiatric work-up. Psychiatric comorbidities were assessed with a semistructured clinical interview according to ICD-10 criteria and validated by clinical observation over a period of more than 3 weeks of in-patient care. Furthermore, almost all patients underwent psychometric assessment using three validated and generally used instruments (German editions): the Hospital Anxiety and Depression Scale (HADS) is used to determine the level of anxiety and depression a patient experienced in the previous week (two scales with seven items each with a score 0–21) (14). The Brief Symptom Inventory (BSI) is a self-reported inventory with subscales to assess symptom groups concerning somatization, obsessive–compulsive symptoms, interpersonal sensitivity, depression, phobic anxiety, paranoia, and psychoticism (Global Severity Index: 0–3 points; Positive Symptom Total: 0–53 points; Positive Symptom Distress Index: 0–3 points) (15). The Perceived Stress Scale (PSS) is a widely used instrument for measuring non-specific perceived stress (14 items: 0–56 points) (16).
Statistical analysis For statistical analysis, we used SPSS 17 for Windows (SPSS Inc, Chicago, IL, USA). Normal distribution was tested with the Kolmogorov–Smirnoff test and if not fulfilled, non-parametric statistical analyses were used. We used descriptive statistics to compare patient groups across sociodemographic data, clinical symptoms, pain history, adverse life events, psychiatric comorbidity, and medications. Group comparisons for categorical variables used Pearson’s χ 2 test or Fisher’s exact test where appropriate. The Mann–Whitney test or an independent sample test was used for comparisons of continuous variables. Variables are expressed as percentages and medians (interquartile range). The level of significance was set at p < 0.05 (two-tailed). We used Spearman’s rho correlation coefficient to test for associations between the SSS, the WPI score, and the described psychosocial variables (HADS; BSI; PSS) as well as algometry data and baseline pain measurement. With regard to psychometric data, we used sum scores. To adjust for multiple comparisons, only pvalues < 0.003 were deemed to be statistically significant.
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Figure 1. Overview of the cohort of patients with functional pain syndromes including the subgroups with fibromyalgia (FM) according to the ACR 1990 and 2010 criteria.
distribution for the 300 patients with respect to WPI and SSS is shown in Figures 2 and 3, respectively. Of the 300 patients with functional pain syndromes investigated in this study, 25 (8.3%) met the ACR 1990 criteria for diagnosis of FM. Of these, 21 (84%) also fulfilled the ACR 2010 criteria. In total, 130 (43.3%) out of the cohort of 300 patients with functional pain syndromes met the new FM 2010 criteria. Twenty-one patients met both the 1990 and 2010 criteria for FM, 109 patients met only the 2010 and not the 1990 criteria. In the subgroup not meeting the ACR 1990 criteria (n ¼ 275), we found the following pain diagnoses and their combinations: chronic cervical pain syndromes; 60
Fibromyalgia according to ACR 1990, n = 25 Fibromyalgia according to ACR 2010, n = 109 Other functional pain syndromes, n = 168
50
40
30
20
10
0
Results
25 FM according to ACR 1990 21
109
Frequency
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Psychometry
0
1
2
3
4
5
6 7 SSS
8
9 10 11 12
General patient characteristics Figure 1 gives a quantitative overview of the patient population, including subgroups. The frequency
Figure 2. Frequency distribution in the total cohort of 300 patients with functional pain syndromes and fibromyalgia (FM) in relation to the Symptom Severity Score (SSS).
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45 40
Fibromyalgia according to ACR 1990, n = 25 Fibromyalgia according to ACR 2010, n = 109 Other functional pain syndromes, n = 168
35
Frequency
30 25
An analysis of the pain distribution pattern in patients according to the ACR 2010 criteria showed that less than half of all patients (46%) suffered from pain in all four quadrants. Whereas 10.4% of FM 2010 patients suffered from unilateral pain syndromes, in 9.6% pain was limited to the head and trunk or to the upper part of the body; 10.4% of FM 2010 patients had local pain syndromes affecting just one or two quadrants. The remainder showed other forms of ‘incomplete’ distribution patterns.
20 15
How to distinguish between FM 2010 and the spectrum of functional pain disorders as a whole
10 5
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0
0 1 2 3 4 5 6 7 8 9 1011121314151617181920 WPI
Figure 3. Frequency distribution in the total cohort of 300 patients with functional pain syndromes and fibromyalgia (FM) in relation to Widespread Pain Index (WPI).
atypical chronic limb syndromes; functional hemisided or quadrantomal pain syndromes; chronic chest, trunk, chest, or low back pain; chronic tension headache; chronic temporomandibular disorder; chronic atypical facial pain syndrome; irritable bowel syndrome; chronic abdominal pain and chronic pelvic pain syndromes. One hundred and seventy patients (56.7%) did not meet either the 1990 or the 2010 ACR criteria. Two patients in this group were excluded from further analysis because of insufficient data so that the group comparison was performed with 168 patients without a diagnosis of FM 2010.
Similarities and differences between FM 1990 and FM 2010 Table 1 shows the group comparison of the 25 patients with FM 1990 and the 109 patients who met only the ACR 2010 criteria. No differences between the two groups were seen with respect to pain perception in tissues (mainly deep pain sensation), dominant pain quality (burning, stabbing, dragging pain, etc.), average pain duration, pain dynamics, and factors modulating pain as well as the effects of medication and the algometric assessment of pain sensitivity. The groups also did not differ in associated somatic complaints, extent of psychiatric comorbidities, level of stress, and adverse life events profile. In the group diagnosed according to the ACR 2010 criteria, there were significantly more patients with post-traumatic stress disorder (p ¼ 0.04), a history of accidents (p ¼ 0.03), and a history of migration background (p ¼ 0.02). The FM 2010 group showed higher average values of the SSS (p ¼ 0.03). By contrast, the group diagnosed with FM 1990 criteria had an increased WPI score (p ¼ 0.03).
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Table 2 shows a group comparison between all 130 patients meeting the ACR 2010 criteria (including the 21 patients also fulfilling the ACR 1990 criteria) and the 168 remaining patients with functional pain syndromes without a diagnosis of FM. The group with FM 2010 could be distinguished from the comparator group by significantly higher WPI and SSS scores (p < 0.001) and by increased pain levels (p < 0.001). Pain sensitivity, as assessed by algometry, also showed significantly higher levels in the FM group (middle finger: p ¼ 0.007, earlobe: p ¼ 0.003). All three functional criteria of pain drawings (i.e. number of marks, length of the largest mark, and elements of axial symmetry) showed significantly increased values in the FM 2010 group (p < 0.001). In four out of nine examined cases of associated somatic complaints, FM 2010 patients on average showed significantly more often symptoms (insomnia, dizziness, tension headache, atypical chest pain). FM 2010 patients did not differ from patients with other functional pain syndromes in age, gender distribution, pain localization in tissues (mainly deep pain), quality of pain (burning, stabbing, dragging pain, etc.), pain duration, and effects of medication. As far as adverse life events are concerned, the FM 2010 group showed a higher rate of both partner conflicts (p ¼ 0.03) and migration background (p ¼ 0.01). With regard to psychiatric co-diagnoses, the comorbidity rate of depression was significantly increased in the FM 2010 group compared with the group diagnosed with functional pain syndromes without FM (p < 0.001). In addition, a difference in incidence was noted with regard to post-traumatic stress disorders (p ¼ 0.03). The FM 2010 group had significantly higher scores in all assessed psychiatric comorbidity tests (HADS depression, HADS anxiety, and BSI) and also in stress exposure (p < 0.01).
Correlation of the WPI and the SSS Table 3 shows the correlation ratios of the WPI and the SSS with other investigated continuous indicators.
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Table 1. Fibromyalgia (FM) according to ACR 2010 criteria vs. ACR 1990 criteria.
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Variable Sex (male) Age (years) WPI SSS Pain duration (months) Pain intensity (NRS) Pain quality Stabbing Burning Pinching Pain dynamics Constant/with pain-free intervals Pain modulation Increase on mechanical stress Increase on psychological stress and nervousness Relief on relaxation Relief on physiotherapy Relief on application of heat Algometry Pain test on middle finger (NRS) Pain test on earlobe (NRS) Pain drawing Number of marks Length of longest mark Axial symmetry properties Concomitant complaints Insomnia Formication Nausea Dizziness Tension headache Irritable bowel syndrome Chronic genitourinary complaints Atypical chest pain Atypical facial pain Adverse life events Major accident event Migration background (first generation) Long-standing partner conflicts Adverse childhood experience Persistent overwork on the job Concomitant psychiatric diagnosis Post-traumatic stress disorder Depression Anxiety disorder Psychometry (SD) BSI – Total score HADS – Depression HADS – Anxiety PSS
FM according to ACR 2010 criteria (n ¼ 109)
FM according to ACR 1990 criteria (n ¼ 25)
p-value
Effect size
47.7 48 (43–54) 7 (5–9) 9 (8–10) 60 (18–120) 75 (6–8)
4.0 51 (48–57) 9 (6–13) 8 (7–9) 84 (21–162) 7 (6 –9)
< 0.001*** 0.19 0.03* 0.03* 0.52 0.99
1.11 0.29 0.46 0.46 0.06 0.01
28.0 20.0 17.2
33.3 33.3 20.8
0.79 0.16 0.68
0.06 0.13 0.04
86.4/13.6
91.9/8.7
0.52
0.06
72.2 33.3
76.0 36.0
0.70 0.80
0.03 0.02
17.6 33.3 26.9 79.3 4 (1–6) 8.5 (6–11) 89.9 11 (8–17) 43.5 (23–65) 75.5
24.0 24.0 20.0 76 4.5 (1–8) 9 (6–11) 80.0 15.5 (8–23) 38.0 (15–73) 90.0
0.46 0.37 0.48
0.06 0.28 0.06
0.32 0.76
0.25 0.08
0.16 0.66 0.15
0.43 0.02 0.13
53.2 16.0 11.3 17.9 27.5 9.2 8.3 16.5 5.5
60.0 16.7 8.3 12.5 16.0 20.0 0.0 8.0 8.0
0.54 0.94 0.67 0.52 0.23 0.12 0.14 0.28 0.64
0.05 0.09 0.04 0.06 0.10 0.13 0.13 0.09 0.04
56.0 69.7
32.0 44.0
0.03* 0.02*
0.19 0.21
52.3 45.9 59.6
64.0 56.0 76.0
0.29 0.36 0.13
0.09 0.08 0.13
22.0 86.2 19.3
4.0 88.0 28.0
0.04* 0.82 0.33
0.18 0.02 0.08
1.01 (0.60–1.00) 11.0 (5.0–14.0) 8.0 (4.0–15.0) 26.5 (18–34)
0.94 0.92 0.08 0.42
0.02 0.07 0.40 0.22
1.10 (0.70–1.00) 10 (7–15) 11 (8–14) 29 (24–40)
ACR, American College of Rheumatology; WPI, Widespread Pain Index; SSS, Symptom Severity Score; NRS, Numerical Rating Scale; BSI, Brief Symptom Inventory; HADS, Hospital Anxiety and Depression Scale; PSS, Perceived Stress Scale. Values given as percentage, mean standard deviation, or median (interquartile range).
In absolute values, the WPI score showed the greatest correlation with the finger algometric data (r ¼ 0.18; p < 0.001), whereas the SSS correlated greatest with psychometric BSI measure (r ¼ 0.39; p < 0.001), which was the same for the combined WPI and SSS score (r ¼ 0.28; p < 0.001). All correlation coefficients were positive,
confirming the assumption of a direct relationship between psychological burden and pain symptoms as well as the symptom severity index. Although effect sizes were only small to medium, most of the correlation coefficients remained significant after controlling for multiple comparisons.
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Table 2. Pain properties of fibromyalgia (FM) according to ACR 2010 criteria vs. other functional pain syndromes.
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Variable Sex (male) Age (years) WPI SSS Pain duration (months) Pain intensity (NRS) Pain quality Stabbing Burning Pinching Pain dynamics Constant/with pain-free intervals Pain modulation Increase on mechanical stress Increase on psychological stress and nervousness Relief on relaxation Relief on physiotherapy Relief on application of heat Algometry Pain test on middle finger (NRS) Pain test on earlobe (NRS) Pain drawing Number of marks Length of longest mark Axial symmetry properties Concomitant complaints Insomnia Formication Nausea Dizziness Tension headache Irritable bowel syndrome Chronic genitourinary complaints Atypical chest pain Atypical facial pain Adverse life events Major accident event Migration background (first generation) Long-standing partner conflicts Adverse childhood experience Persistent overwork on the job Concomitant psychiatric diagnosis Post-traumatic stress disorder Depression Anxiety disorder Psychometry (SD) BSI – Total score HADS – Depression HADS – Anxiety PSS
FM according to ACR 2010 criteria (n ¼ 130)
Other functional pain syndromes (n ¼ 168)
p-value
Effect size
41.5 49 (43–55) 8 (5–10) 9 (8–10) 60 (18–130) 7.5 (6–9)
48.8 48 (39–57) 3 (1–5) 6 (4–7) 53 (15–130) 6.5 (5–8)
0.20 0.52 < 0.001*** < 0.001*** 0.33 < 0.001***
0.01 0.08 1.69 1.45 0.01 0.48
30.0 24.2 17.6
33.1 28.2 15.3
87.7/12.3
70.3/29.7
73.6 34.1
0.63 0.52 0.72
0.10 0.10 0.05
0.002***
0.21
72.9 21.1
0.75 0.03*
0.04 0.15
19.4 31.8 25.6 79.3 4.08 2.96 7.94 3.04 88.5 12 (8–18) 45 (23–66) 77.4
18.6 32.3 22.8 63.3 3.01 2.47 6.87 3.09 77.4 6 (3–9) 20 (10–36) 48.8
0.78 0.86 0.59
0.05 0.03 0.06
0.007** 0.003**
0.40 0.35
< 0.001*** < 0.001*** < 0.001***
0.61 0.89 0.27
55.4 16.7 10.3 16.7 26.2 10.8 8.5 15.4 6.2
42.3 11.4 11.4 6.6 14.3 7.7 7.1 5.4 5.4
0.03* 0.37 0.84 0.02* 0.02* 0.60 0.84 0.01* 0.90
0.15 0.08 0.03 0.16 0.16 0.06 0.03 0.17 0.16
51.5 66.2
47.6 48.2
0.30 0.01**
0.09 0.18
53.8 47.7 62.3
41.1 56.5 59.5
0.03* 0.32 0.47
0.04 0.10 0.03
19.2 86.9 21.5
8.9 63.7 19.0
0.03* < 0.001*** 0.68
15 0.26 0.05
< 0.001*** < 0.001*** < 0.001*** < 0.01**
0.61 0.51 0.50 0.44
1.1 (1–2) 10 (7–15) 11 (8–14) 29 (24–38)
0.7 0 (0.4–1) 8 (4–11) 8 (5–12) 27 (17–32)
ACR, American College of Rheumatology; WPI, Widespread Pain Index; SSS, Symptom Severity Score; NRS, Numerical Rating Scale; BSI, Brief Symptom Inventory; HADS, Hospital Anxiety and Depression Scale; PSS, Perceived Stress Scale. Values given as percentage, mean standard deviation, or median (interquartile range).
Discussion FM 2010, the ‘severe half’ of the functional pain syndromes Of patients who met the FM 1990 criteria (n ¼ 25), 84% also fulfilled the 2010 criteria. Thus, there is undoubtedly
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high internal congruence of pain characteristics between FM 1990 and FM 2010. These data are congruent with data from other studies (4, 5). With respect to the whole group of functional pain syndromes, Figures 2 and 3 show that FM (1990 and
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Table 3. Spearman’s rho correlation of the WPI and SSS with other continuous variables in functional pain syndromes.
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WPI/Finger algometry WPI/Earlobe algometry WPI/Baseline pain SSS/HADS SSS/HADS – Anxiety SSS/HADS – Depression SSS/BSI SSS/PSS WPIþSSS/Finger algometry WPIþSSS/Earlobe algometry WPIþSSS/Baseline pain WPIþSSS/HADS WPIþSSS/HADS – Anxiety WPIþSSS/HADS – Depression WPIþSSS/BSI WPIþSSS/PSS
r
p
0.25 0.22 0.22 0.33 0.20 0.31 0.39 0.24 0.18 0.18 0.23 0.27 0.26 0.24 0.28 0.21
< 0.001*** 0.001*** < 0.001*** < 0.001*** < 0.001*** < 0.001*** < 0.001*** < 0.01 0.01 0.01 < 0.001*** < 0.001*** < 0.001*** < 0.001*** < 0.001*** < 0.01
WPI, Widespread Pain Index; SSS, Symptom Severity Score; HADS, Hospital Anxiety and Depression Scale; BSI, Brief Symptom Inventory; PSS, Perceived Stress Scale. ** < 0.01; ** < 0.001.
2010) is seamlessly embedded in this spectrum. With regard to SSS and WPI, the ACR 2010 criteria approximately select the right-hand half of the bellshaped curve within this spectrum. This almost Gaussian frequency distribution does not show any twin-peak pattern, giving no indication of a real discriminant diagnostic function of the WPI and SSS in this spectrum. The ‘more severe half’ of the spectrum of all functional pain syndromes is labelled as FM with the new ACR 2010 criteria.
Increase in FM diagnoses according to the ACR 2010 criteria Among the 300 patients with functional pain disorders, 43.3% fulfilled the FM 2010 criteria. The phenotype of FM 1990 in the same group was diagnosed in only 8%. As a potential methodological bias, it should be pointed out that all 300 patients were systematically screened with the ACR 2010 criteria, whereas the tender point test was carried out only in those patients with clinical suspicion of FM 1990 based on the ‘widespread pain criterion’. Nonetheless, the basic point made remains the same: depending on the point of reference chosen (ACR 1990 criteria or ACR 2010 criteria), our data suggest that, under the old diagnostic system, many FM patients were ‘missed’ (false negative); the systematic use of the ACR 2010 criteria, by contrast, would result in many patients being diagnosed with FM who would not have been diagnosed with this condition before (overdiagnosis).
Heterogeneous pattern of the anatomical distribution of FM 2010 So far, FM (according to the ACR 1990 criteria) has been considered the ‘whole-body variant’ of functional pain syndromes (3). The ACR 2010 criteria yield a more heterogeneous picture as far as the anatomical pattern of distribution is concerned. This is because the ‘widespread pain criterion’ used in the 1990 definition of FM (axial pain, left- and right-sided pain, and pain in the upper and lower body segments) is no longer applied. Meanwhile, the ACR criteria 2010 follow a ‘double logic’: On the one hand, the probability of diagnosing FM 2010 appears to be greater the more a pain syndrome is multifocal in nature (high WPI score); on the other hand, a mere shoulder-arm syndrome could be labelled as FM too, if the SSS is sufficiently high (e.g. in depressive patients). With regard to these ‘new’ cases of FM with strictly localized pain (10.4% in our FM cohort), the question arises as to how the 2010 criteria are able to differentiate FM from, for example, myofascial pain syndromes (17). In addition, functional pain syndromes with hemibody distribution (in our FM 2010 cohort a further 10.4%) were classified as FM, although they can otherwise be characterized in a clearly more specific way (18–20). In sum, the ACR 2010 criteria do not help to differentiate ‘incomplete forms of FM’ from other forms of chronic widespread pain but instead result in a mixing up of terms (9). For this reason, this aspect of the ACR 2010 criteria was criticized for being ‘inconsistent’ and causing a ‘dilution’ of the former concept of FM 1990 (6).
Symptom scores never provide a diagnosis Originally, the declared aim of the ACR 2010 was ‘to develop simple, practical criteria for the clinical diagnosis of fibromyalgia’ (3). Contrary to the Budapest criteria for complex regional pain syndromes (21), the ACR 2010 criteria ‘diagnose’ FM solely on the basis of symptoms mentioned in the patient history; that is they do not take into account criteria that can be clinically examined. This methodological approach was subject to criticism from the very beginning (6, 8, 9). Regarding the ‘modified’ ACR 2010 criteria, the ACR author team went even a step further in that patients could self-declare and score their own symptoms (this even eliminated the need for diagnostic medical interviews). This approach results in a failure to provide a diagnostic instrument fit for clinical purpose; according to a study by Wolfe et al (7), as few as 60% of patients with FM 1990 as an entry diagnosis fulfilled the modified ACR 2010 criteria, while 37% of patients with systemic lupus erythematosus (SLE) also met the new diagnostic criteria of FM 2010. Furthermore, the ACR 2010 criteria did not help in differentiating false diagnoses from actual double diagnoses (7). The resulting loss of specificity and differentiation has not remained unnoticed (6, 9).
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There is no way around a clinical diagnosis of FM Both the above-mentioned study by Wolfe et al (7) and our own data raise a fundamental question of methodology; namely, to what extent are symptom scores typical of a disease suitable as a diagnostic instrument? For instance, no specialist in internal medicine would be likely to confuse the New York Heart Association (NYHA) criteria for quantifying dyspnoea in heart failure with the diagnosis of the underlying cardiopathy. In other words, the symptom scores used for monitoring progression (e.g. in studies) are not the type of instrument needed or suitable for the clinical diagnosis of diseases. As it did not seem clear from the outset that the ACR 2010 criteria would prove to be suitable for clinical diagnosis of FM in primary and speciality care settings, the authors of the ACR 2010 criteria added a quasicautionary comment: ‘It is important to exclude other causes of chronic widespread pain or identify potential coexisting rheumatic diseases’ (2). This diagnosis by exclusion becomes problematic because FM is often diagnosed concurrently with a variety of other diseases (1, 7, 22). If FM becomes a diagnosis by exclusion, it means that the ACR 2010 criteria failed to include sufficient entity-specific characteristics. In search of entity-specific criteria, Yunus (1) already suggested several years ago that generalized hyperalgesia (central sensitivity) is the core pathophysiological element of FM and overlapping disorders. Along with numerous previous studies (23– 26), our algometric data confirm that the feature of hyperalgesia is a crucial characteristic of this pain disorder. In assessing tender points according to the ACR 1990 criteria, the clinical screening automatically focused on generalized allodynia/hyperalgesia. Even if the majority of experts today agree that a painstaking interpretation and count of tender points misses the intended target (2), there are still some valid concerns that totally abandoning the tender point concept would imply abandoning the strategy of screening for generalized hyperalgesia. It would seem that dropping the tender point concept is not only the main advantage of the ACR 2010 criteria but also their greatest drawback. We do not suggest reinstating the old concept of tender points; instead, we recommend that the clinical finding of generalized hyperalgesia should be reintegrated and operationalized as a standardized algometric procedure. If we keep the focus in FM on the aspect of generalized hyperalgesia, it will automatically become possible to delimit FM against the whole puzzle of localized pain syndromes.
Mental symptoms in FM An improvement in the ACR 2010 criteria worth mentioning is the fact that the SSS now incorporates mental symptoms, which make it clear that FM is not just one among several musculoskeletal diseases but a complex processing disorder of pain and stress (27–29). The
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N Egloff et al
influence of chronic stress on increased pain perception should be the centre of future FM research and therapy (30). Several studies using animal models help to untangle the mechanisms leading to stress-induced hyperalgesia both at the central and peripheral level (31–34). Like many earlier studies (35–38), our data, too, confirm the existence of a correlation between FM and psychosocial stressors: about 60% of our patients complained of being persistently overworked in their jobs. There is clinical manifestation of depressive disorder in more than 85% concomitantly with their pain condition. Our investigations provide proof of arithmetic correlation between the SSS and the psychometrically assessed burden imposed by depression and stress (p < 0.001). With regard to its therapeutic consequences, the question arises as to whether directly assessing the burden of stress and depression in FM might not be more meaningful than checking 40 confusing bodily symptoms as required by the SSS. To summarize, the ACR 2010 criteria clearly alter the case definition of FM. By omitting the requirement of ‘generalized pain’, the distinction between the FM and more localized functional pain syndromes is blurred. Furthermore, by dropping the tender point assessment, the ACR 2010 criteria omit examination of the distinctive ‘hyperalgesia aspect’ of FM. The ACR 2010 symptom checklists are no doubt very simple to use, but as a matter of principle, a new research-based concept of FM should include rather than avoid pathophysiological findings. There is a quote attributed to Albert Einstein: ‘Everything should be made as simple as possible, but not simpler’. It remains to be hoped that these issues will be taken into consideration in the ongoing discussion on FM criteria. Acknowledgements We thank JP Geri, A Kocher, and R Csordas-Iyer for editorial assistance.
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