Fibromyalgia revisited: do latent class analyses of symptom profiles in the general population confirm 2016 fibromyalgia diagnostic criteria?
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Fibromyalgia revisited: do latent class analyses
of symptom profiles in the general population
confirm 2016 fibromyalgia diagnostic criteria?
B. Schmalbach1, W. Häuser2,3, E. Brähler4, P. Henningsen2, F. Wolfe5
1
Department of Medical Psychology ABSTRACT Introduction
and Medical Sociology, University Objective. The definition of the 2016 The definition and content of fibromy-
Medical Centre of the Johannes diagnostic criteria of fibromyalgia algia (FM) syndrome have changed re-
Gutenberg University Mainz;
(FM) syndrome and of FM severities peatedly in the 110 years of its existence
2
Department of Psychosomatic Medicine
and Psychotherapy, Technische was based on studies with clinical sam- (1). The most important change arose
Universität München; ples. We tested if somatic symptom pro- in the 1990s by the American College
3
Department of Internal Medicine 1, files consistent with the symptom pat- of Rheumatology (ACR) classification
Klinikum Saarbrücken; tern of the FM 2016 diagnostic criteria criteria which defined FM by symp-
4
Department of Psychosomatic Medicine and of severities of FM can be found in toms (chronic widespread pain [CWP])
and Psychotherapy, University Medical the general population. and findings (tenderness at palpation of
Centre of the Johannes Gutenberg
Methods. Somatic symptom burden was muscles and tendons) (2). By 2010, a
University Mainz, Germany;
5
National Data Bank for Rheumatic measured by the Somatic Symptom Scale second shift occurred that excluded ten-
Diseases, Wichita, USA. - 8 in 2,531 persons aged ≥14 years rep- der points. These new criteria overcame
Bjarne Schmalbach, PhD* resentative for the general German pop- the requirement for specialist medical
Winfried Häuser, MD* ulation. We used latent class analysis of examinations. Some patient-reported
Elmar Brähler, PhD SSS-8 items to identify somatic symptom non-musculoskeletal pain symptoms
Peter Henningsen, MD profiles. The profiles were described (headache, abdominal pain) and psy-
Frederick Wolfe, MD by their association with age, gender, chological symptoms (fatigue, cogni-
*These authors contributed equally. self-reported disabling somatic disease, tive problems, depression) were added
Please address correspondence to: psychological symptom burden, illness as minor diagnostic criteria (3). FM be-
Winfried Häuser, worries and self-perceived health. came a symptom-based diagnosis that
Department of Psychosomatic Results. We identified five somatic included multiple somatic and psycho-
Medicine and Psychotherapy, symptom profiles. The majority of the logical symptoms. In the 2016 diagnos-
Technische Universität München,
Langerstrasse 3,
population (40.9%) had a profile char- tic criteria (4), the criteria of CWP was
81675 München, Germany. acterised by the absence of bothering tightened compared to the 1990 classifi-
E-mail: symptoms. 5.9% had a profile defined by cation criteria (2) requiring pain sites in
whaeuser@klinikum-saarbruecken.de “considerable bothering” back and ex- at least four of five body regions.
Received on January 30, 2021; accepted tremities pains, fatigue and sleep prob- All studies defining the ACR 1990 clas-
in revised form on April 22, 2021. lems. This symptom profile was associat- sification (2), the 2010 ACR prelimi-
Clin Exp Rheumatol 2021; 39 (Suppl. 130): ed with older age, self-reported somatic nary diagnostic (3), the 2011 (5) and
S128-S136. diseases, psychological symptom burden the 2016 (4) criteria were conducted
© Copyright Clinical and and fair to poor general health. 63.2% with people with various rheumatic dis-
Experimental Rheumatology 2021. of persons meeting FM 2016 criteria eases included in the US National Data
belonged to this profile. 17.8% of the Bank of Rheumatic Diseases (5). These
Key words: fibromyalgia, somatic sample were characterised by little per- selections might have led to consider-
symptoms, psychosomatic medicine, turbation by multiple somatic symptoms able bias in the identification of symp-
latent class analysis, representative and good to fair general health. 36.8% tom classes including higher symptom
survey of persons meeting FM 2016 criteria be- prevalence in the study population (6).
longed to this profile. Previous studies have shown a lower
Conclusion. Two somatic symptom symptom burden of FM-cases in the
profiles consistent with the 2016 FM general population compared to the
diagnostic criteria were identified in ones of clinical settings (7). A symp-
the general German population. These tom profile in the general population
Competing interests: W. Häuser
has received honoraria for a CD with symptom profiles differed in somatic consistent with the one defined by 2016
medical hypnosis for fibromyalgia by and psychological symptom burden FM diagnostic criteria (4) would sup-
Hypnos publisher. The other authors and general health supporting the dis- port its use in making a clinical diag-
have declared no competing interests. tinction of FM severities. nosis of FM.
S-128 Clinical and Experimental Rheumatology 2021Fibromyalgia revisited / B. Schmalbach et al.
Studies with FM patients in clinical 258 living areas was randomly select- musculoskeletal and general symptoms
care have demonstrated that FM is a ed from a non-overlapping stratum of during the last four weeks. Thus, the
heterogenous condition with regards all area units: 210 areas were sampled BDS-25 asks for negative appraisal
to the amount of somatic and psycho- from Western Germany and 48 areas of somatic symptoms, but not explic-
logical symptom burden, disability from Eastern Germany. The random se- itly for psycho-behavioural symptoms.
and comorbid diseases (7). Therefore, lection of households was implemented Each symptom can be scored on Likert
a distinction of severities of FM has in the second step. Finally, one person Scales from 0 (bothering not at all) to 4
been suggested, e.g. based on clinical matching the inclusion criteria was ran- (bothering a lot) (17). We used the vali-
criteria such as the extent of disability domly selected from each household. dated German version of the BDS-25
and /or symptom scores, e.g. of the Fi- Sociodemographic data were collected (13).
bromyalgia Impact Questionnaire (9) by trained interviewers face-to-face. In
or the Patient Health Questionnaire addition, participants completed a bat- The Patient Health Questionnaire-4
(PHQ) 15 (7, 10). The studies on se- tery of self-report questionnaires. The (PHQ-4) was used to assess psycho-
verities of FM were conducted with interviewers waited until the partici- logical symptom burden. On Likert
clinical populations (7, 9) and require pants answered all questionnaires, and scales from 0 (not at all) to 3 (nearly
testing in the general population, too. offered help in case of ambiguities. every day), respondents rate how often
The latent class approach (LCA) has they have been bothered by little inter-
proven to be a powerful analytical ap- Instruments est or pleasure in doing things and feel-
proach for diagnosing symptom pat- Demographics: Age, gender, family ing down, depressed or hopeless, feel-
terns in the general population (6, 11). status, educational level, and net fam- ing nervous, anxious or on edge, or not
Previous studies have found “healthy”, ily income per month were assessed by being able to stop or control worrying
specific symptom and multi-symptom a standardised questionnaire used pre- over the last two weeks. The total score
profiles in the general population (6, 12). viously in German health surveys (15). ranges from 0 to 12. Scores are rated
We studied profiles of somatic symp- as normal (0-2), mild (3-5), moderate
toms by LCA in the general population The Somatic Symptom Scale-8 (SSS-8) (6-8), and severe (9-12) psychologi-
in order to assess: is the short form of the Patient Health cal symptom burden (18). We used the
• If profiles which are consistent with Questionnaire PHQ-15 (10) and asks validated German version (19).
the symptom pattern of the 2016 FM for eight somatic symptoms during the
criteria can be found; past 7 days (stomach or bowel prob- The Michigan Body Map (MBM) is a
• If these somatic symptom profiles lems; back pain; pain in arms, legs, or graphic mannequin for the assessment
differ in the amount of somatic and joints; headaches; chest pain or short- of chronic pain. It offers 35 checkbox
psychological symptom burden and ness of breath; dizziness; feeling tired body areas covering all 19 areas from
in general health supporting the con- or having low energy; trouble sleep- the Widespread Pain Index (WPI) (4)
cept of severities of FM. ing). Symptoms are scored on Likert plus 16 other pain sites (20). Subjects
Scales from 0 (not bothered at all) to are asked to mark all areas where they
Materials and methods 4 (bothered very much) (16). We re- have felt persistent or recurrent pain
Design and subjects coded as follows: 0=0; 1 and 2=1; 3 present for the last three months or
The study is part of a larger cross-sec- and 4=2 because a) 4-scores were very longer. We used the German version of
tional survey on physical and mental rare (Fibromyalgia revisited / B. Schmalbach et al.
and pains?”; “Do you find that you Table I. Fit criteria for latent class models with 1-10 components.
are bothered by many different symp-
# of latent clusters LL df BIC CAIC
toms?”) because they capture symptom
quantity rather than illness conviction 1 -14016.07 2363 28156.53 28172.53
(WI-5). We used the validated German 2 -11944.48 2346 24145.52 24178.52
version (22). 3 -11567.86 2329 23524.44 23574.44
4 -11408.47 2312 23337.82 23404.82
5 -11302.05 2295 23257.16 23341.16
The self-administered comorbidity 6 -11239.02 2278 23263.26 23364.26
questionnaire (SCQ) is a validated self- 7 -11189.62 2261 23296.63 23414.63
rating instrument in clinical and health 8 -11160.14 2244 23369.82 23504.82
services research to assess common dis- 9 -11131.24 2227 23444.19 23596.19
10 -11103.44 2210 23520.76 23689.76
eases. It asks about the presence, treat-
ment, and functional limitations of thir- LL: log likelihood; df: degrees of freedom; BIC: Bayesian information criterion; CAIC: consistent
teen common diseases (heart disease; Akaike information criterion.
high blood pressure; lung disease; dia- Model with best fit is printed in bold.
betes; ulcer or other stomach disease;
kidney disease; liver disease; anaemia of FM (5) were recorded as follows: should only be related to a negligible
or other blood disease; cancer; rheuma- Fatigue and sleeping problems when degree (similar to the error terms in
toid arthritis. We substituted osteoar- reported by SSS-8 items 7 and 8 as at confirmatory factor analysis). The pri-
thritis by pancreas disease and low back least “somewhat bothering”; cognitive mary measures of interest in the LCA
pain by inflammatory bowel disease to problems when reported BDS item 24 are then the Bayesian Information Cri-
a) avoid overlap with pain sites assessed was rated as at least “somewhat both- terion (BIC) and the Consistent Akaike
by the WPI b) to increase the number of ering; headache when BDS 25 item 23 Information Criterion (CAIC). In line
somatic diseases which might contrib- was rated as at least “somewhat bother- with the typical recommendation, we
ute to somatic symptoms captured by ing”; pain or cramps in the lower ab- also ran bootstrapped (i=100) LCAs to
the BDS 25 checklist. Three subscales domen when BDS 25 item 8 was rated ascertain the initial results (29).
(present disease, present disease with as at least “somewhat bothering”; de- Subsequently, we compared the result-
drug treatment, present disease with as- pression when PHQ 4 item 2 was rated ing classes with regard to their sociode-
sociated disability) are available (23). as at least “at several days”. Scores of mographic characteristics as well as
We used the subscale “present disease ACRSSS range from 0-12. Polysymp- their descriptive statistics for both, the
with associated disability” (range 0-12) tomatic Distress Scale score (PDS) is SSS-8 items and scales, and other relat-
of the validated German version (24). the sum of the WPI and SSS. Scores ed measures and variables. For metric
range from 0-31. We used these PPS variables, we used univariate ANOVAs
The Short Health Survey 12 (SF-12) severity categories: none (0-3), mild (4- and report the η² effect size, which ac-
General Health concept was used to as- 7), moderate (8-11), severe (12-19), and cording to Cohen (30, 31) should be
sess self-perceived health on a 5-point very severe (20-31). FM was defined as interpreted as signifying small, moder-
Likert scale. Subjects were straight 1) WPI ≥ 7 and SSS ≥5 OR WPI 4-6 ate, and large effects for values exceed-
asked “In general, would you say and SSS ≥9, AND 2) pain in 4 of 5 body ing 0.01, 0.09, 0.25. In addition, we
your health is….”. The answers are as regions (4). conducted post-hoc group comparisons
follows: 1=excellent; 2=very good; Self-reported FM: Participants were using Holm-corrected t-tests.
3=good; 4= moderate; 5=poor self-per- asked if they have been diagnosed with For count variables, we utilised the χ²
ceived health’ (25). We used the vali- FM by a physician in the past. test to investigate whether there are
dated German version (26). significant between-group differences.
Statistical analyses We report Cramer’s V as an effect size
Case definitions of FM All analyses were conducted in R. Only for these analyses, which is defined as
We used two case definitions of FM complete cases were included: n = the root of χ² divided by the product
because: a) there is no gold standard 2,379. We then utilised poLCA (28) to of the sample size and dfA, where dfA
for FM diagnosis; b) considerable disa- perform a latent class analysis with the is the length of the smaller of the two
greement between clinical diagnosis items of the SSS-8. This technique al- dimensions minus 1 (30). In addition,
and criteria-based diagnosis of fibro- lows for the clustering of observations we applied the correction suggested by
myalgia was found in an US rheumatol- with regard to a given number of char- Bergsma (32) which delivers a more
ogy clinic (27). acteristics. Prior to computing the LCA accurate estimate of the population
2016 criteria: MBM pain sites and pain model, we tested the assumption of con- effect size. For dfA = 1, Cramer’s V is
regions were counted (excluding jaw, ditional independence, which was met interpreted analogously to the Pearson
chest, and abdominal pain). In addi- with only minor deviations for the indi- r coefficient with small, moderate, and
tion, the Somatic Severity Scale (SSS) cators. This means that, after accounting large effects being identified by values
criteria of the 2011 diagnostic criteria for classification the indicator variables of 0.10, 0.30, and 0.50, respectively.
S-130 Clinical and Experimental Rheumatology 2021Fibromyalgia revisited / B. Schmalbach et al.
Table II. Relative response frequencies for the SSS-8 items.
Total sample 1 2 3 4 5 Group comparison
Item n 2379 973 435 424 407 140
% 100 41 18 18 17 6
Stomach or bowel problems Not at all 72 95 63 76 34 28 χ²(8) = 140.47, pFibromyalgia revisited / B. Schmalbach et al. Table III. Sociodemographic characteristics for the overall sample and the latent classes. Total Profile Profile Profile Profile Profile Group-comparison 1 2 3 4 5 n 2379 - 973 435 424 407 140 % - 100 41 18 18 17 6 Sex χ²(4) = 7.68, p=0.104, V = 0.086 Male 1116 47 54 36 53 39 35 Female 1263 53 46 64 47 61 65 Age F(4, 2374) = 74.70, p
Fibromyalgia revisited / B. Schmalbach et al. Table IV. Mean values and standard deviations SSS-8 scale score and external criteria. Total Profile Profile Profile Profile Profile Group comparison Pairwise 1 2 3 4 5 comparisons* SSS-8 (0-16) (Mean, SD) 3.05 (3.06) 0.39 (0.55) 3.57 (1.24) 2.84 (0.94) 6.57 (1.46) 10.33 (2.07) F(4, 2374) = 4135.52, 1 < 3 < 2 < 4 < 5 p
Fibromyalgia revisited / B. Schmalbach et al. Table V. Relative response frequencies for the SSS-8 scale score and external criteria. Total Profile Profile Profile Profile Profile Group comparison 1 2 3 4 5 % 100 41 18 18 17 6 SSS-8 (0-15) 0-3 64 100 54 75 0 0 χ²(16) = 588.38, p15 0 0 0 0 0 1 WPI (0-19) 0 72 96 80 63 31 20 χ²(12) = 166.61, p5 6 0 0 2 18 39 PSD (0-31) 0-3 72 100 69 83 23 1 χ²(16) = 409.71, p
Fibromyalgia revisited / B. Schmalbach et al.
six symptom classes by including 15 4. WOLFE F, CLAUW D, FITZCHARLES MA et J Psychosom Res 2015; 78: 536-45.
al.: Revisions to the 2010/2011 fibromyalgia 18. KROENKE K, SPITZER RL, WILLIAMS JB,
symptoms in LCA (12).
diagnostic criteria. Semin Arthritis Rheum LOWE B: An ultra-brief screening scale for
The identified profiles may describe 2016; 46: 319-29. anxiety and depression: the PHQ-4. Psycho-
clinical recognisable symptom patterns 5. WOLFE F, CLAUW D, FITZCHARLES MA et somatics 2009; 50: 613-21.
from well-defined somatic diseases, al.: Fibromyalgia criteria and severity scales 19. LÖWE B, WAHL I, ROSE M et al.: A 4-item
for clinical and epidemiological studies: A measure of depression and anxiety: valida-
symptom-based diagnoses and short- modification of the acr preliminary diag- tion and standardization of the Patient Health
term unspecific symptoms. The symp- nostic criteria for fibromyalgia. J Rheumatol Questionnaire-4 (PHQ-4) in the general pop-
tom profiles should not be interpreted 2011; 38: 1113-22. ulation. J Affect Disord 2010; 122: 86-95.
as definitions of diseases or new clas- 6. ELIASEN M, JØRGENSEN T, SCHRÖDER A et 20. BRUMMETT CM, BAKSHI RR, GOESLING J et
al.: Somatic symptom profiles in the general al.: Preliminary validation of the Michigan
sifications of disorders but as complex- population: a latent class analysis in a Danish Body Map. Pain 2016; 157: 1205-12.
es of considerably bothering somatic population-based health survey. Clin Epide- 21. FINK P, EWALD H, JENSEN J et al.: Screen-
symptoms of different origin (6). miol 2017; 9: 421-33. ing for somatization and hypochondriasis in
7. HÄUSER W, BRÄHLER E, WOLFE F, HEN- primary care and neurological in-patients: a
NINGSEN P: Patient Health Questionnaire seven-item scale for hypochondriasis and so-
Conclusions 15 as a generic measure of severity in fibro- matization. J Psychosom Res 1999; 46: 261-
Latent class analyses separated the myalgia syndrome: surveys with patients of 73.
continuum of somatic symptom burden three different settings. J Psychosom Res 22. HINZ A, RIEF W, BRÄHLER E: Hypochondrie
in the general German population into 2014; 76: 307-11. in der Allgemeinbevölkerung: Teststatistische
8. FINK P, EWALD H, JENSEN J, SØRENSEN L, Prüfung und Normierung des Whiteley-Index
clinically meaningful profiles. ENGBERG M, HOLM M: Screening for soma- [Hypochondria in the general population:
FM appears to be an invisible experi- tization and hypochondriasis in primary care Test statistical assessment and standardiza-
ence without any visible biomarker and neurological in-patients: a seven-item tion of the Whiteley-Index.] Diagnostica
scale for hypochondriasis and somatization. 2003; 49: 34-42.
to exhibit to healthcare professionals
J Psychosom Res 2006; 60: 137-43. 23. SANGHA O, STUCKI G, LIANG MH, FOSSEL
(38). We identified a somatic symp- 9. SCHAEFER C, CHANDRAN A, HUFSTADER M AH, KATZ JN: The Self-Administered Comor-
tom profile consistent with the major et al.: The comparative burden of mild, mod- bidity Questionnaire: a new method to assess
symptoms of FM according to the 2016 erate and severe fibromyalgia: results from a comorbidity for clinical and health services
cross-sectional survey in the United States. research. Arthritis Care Res 2003; 49: 156-
diagnostic criteria (widespread pain, Health Qual Life Outcomes 2011; 9: 71. 63.
fatigue and sleep problems) in the gen- 10. KROENKE K, SPITZER RL, WILLIAMS JB: 24. STREIBELT M, SCHMIDT C, BRÜNGER M,
eral population supporting a specific The PHQ-15: validity of a new measure for SPYRA K: Comorbidity from the patient per-
diagnostic code for FM in the upcom- evaluating the severity of somatic symptoms. spective - does it work? Validity of a ques-
Psychosom Med 2002; 64: 258-66. tionnaire on self-estimation of comorbidity
ing International Classification of Dis- 11. KATO K, SULLIVAN PF, PEDERSEN NL: (SCQ-D). Orthopade 2012; 41: 303-10.
eases (ICD-11) of the World Health Latent class analysis of functional somatic 25. WARE J, KOSINSKI M, KELLER SD: A 12-Item
Organisation (39). symptoms in a population-based sample of Short-Form Health Survey: construction of
As in clinical populations, FM 2016 twins. J Psychosom Res 2010; 68: 447-53. scales and preliminary tests of reliability and
12. WIRTZ MA, MORFELD M, BRÄHLER E, HINZ validity. Medical Care 1996; 34: 220-33.
cases in the general population differed A, GLAESMER H: Association of physical 26. WIRTZ MA, MORFELD M, GLAESMER H,
in the amount of additional and psy- morbidity and health-related quality of life BRÄHLER E: Normierung des SF-12 Ver-
chological symptom burden, subjec- in a representative sample of older German sion 2.0 zur Messung der gesundheitsbezo-
tive health and comorbid somatic dis- people. Eur J Health Psychol 2019; 25: 140- genen Lebensqualität in einer deutschen bev-
51. ölkerungsrepräsentativen Stichprobe. [Stand-
eases. The heterogeneity of FM should 13. SCHMALBACH B, ROENNEBERG C, ardization of the SF-12 for assessment of
be addressed by targeted and graduated HAUSTEINER-WIEHLE C: Validation of the health-related quality of life in a representa-
management approaches (35, 36). German version of the Bodily Distress Syn- tive German population sample.] Diagnostica
drome 25 checklist in a representative Ger- 2018; 64: 215-26.
man population sample. J Psychosom Res 27. WOLFE F, SCHMUKLER J, JAMAL S et al.:
Acknowledgements 2020; 132; 109991. Diagnosis of fibromyalgia: disagreement
Elmar Brähler was previously affili- 14. HÄUSER W, HENNINGSEN P, BRÄHLER E, between fibromyalgia criteria and clinician-
ated with the University of Leipzig at SCHMALBACH B, WOLFE F: Prevalence and based fibromyalgia diagnosis in a university
overlap of somatic symptom disorder, bod- clinic. Arthritis Care Res 2019; 71: 343-51.
the time of ethics approval. ily distress syndrome and fibromyalgia syn- 28. LINZER DA, LEWIS JB: poLCA: An R Pack-
drome in the German general population: A age for Polytomous Variable Latent Class
References cross sectional study. J Psychosom Res 2020; Analysis. J Statistical Software 2011; 42:
1. WOLFE F, WALITT B: Culture, science and 133: 110111. 1-29.
the changing nature of fibromyalgia. Nat Rev 15. WOLFE F, BRÄHLER E, HINZ A, HÄUSER W: 29. AITKIN M, ANDERSON D, HINDE J: Statistical
Rheumatol 2013; 9: 751-5. Fibromyalgia prevalence, somatic symptom modelling of data on teaching styles. J R Stat
2. WOLFE F, SMYTHE HA, YUNUS MB et al.: reporting, and the dimensionality of poly- Soc Series A General 1981; 144: 419-48.
The American College of Rheumatology symptomatic distress: results from a survey 30. COHEN J: Quantitative methods in psycholo-
1990 Criteria for the Classification of Fibro- of the general population. Arthritis Care Res gy: A power primer. Psychol Bull 1992; 112:
myalgia. Report of the Multicenter Criteria 2013; 65: 777-85. 1155-9.
Committee. Arthritis Rheum 1990; 33: 160- 16. GIERK B, KOHLMANN S, KROENKE K et al.: 31. COHEN J: Statistical power analysis for the
72. The somatic symptom scale-8 (SSS-8): a behavioral sciences. (2nd ed.). Mahwah, NJ,
3. WOLFE F, CLAUW D, FITZCHARLES MA et brief measure of somatic symptom burden. Lawrence Erlbaum, 1988.
al.: The American College of Rheumatology JAMA Intern Med 2014; 174: 399-407. 32. BERGSMA W: A bias-correction for Cramér’s
Preliminary Diagnostic Criteria for Fibromy- 17. BUDTZ-LILLY A, FINK P, ØRNBØL E et al.: V and Tschuprow’s T. J Korean Stat Soc
algia and measurement of symptom severity. A new questionnaire to identify bodily dis- 2013; 42: 323-8.
Arthritis Care Res 2010; 62: 600-10. tress in primary care: The ‘BDS checklist’. 33. HÄUSER W, SCHMUTZER G, BRÄHLER E,
Clinical and Experimental Rheumatology 2021 S-135Fibromyalgia revisited / B. Schmalbach et al.
GLAESMER E: A cluster within the continuum 35. HÄUSER W, PERROT S, CLAUW DJ, tion in counseling and clinical psychology:
of biopsychosocial distress can be labeled FITZCHARLES MA: Unravelling fibromy- A meta-analysis. Educ Psychol Measurement
“fibromyalgia syndrome”- evidence from a algia-steps toward individualized manage- 2009; 69: 389-403.
representative German population survey. ment. J Pain 2018; 19: 125-34. 38. PERROT S: Fibromyalgia: A misconnection
J Rheumatol 2009; 36: 2806-12. 36. MacFARLANE GJ, KRONISCH C, DEAN LE et in a multiconnected world? Eur J Pain 2019;
34. KATZ RS, WOLFE F, MICHAUD K: Fibro- al.: EULAR revised recommendations for 23: 866-73.
myalgia diagnosis: a comparison of clinical, the management of fibromyalgia. Ann Rheum 39. NICHOLAS M, VLAYEN JWS, RIEF W et al.:
survey, and American College of Rheumatol- Dis 2017; 76: 318-28. The IASP classification of chronic pain for
ogy criteria. Arthritis Rheum 2006; 54: 169- 37. HORN PSV, GREEN KE, MARTINUSSEN M: ICD-11: chronic primary pain. Pain 2019;
76. Survey response rates and survey administra- 160: 28-37.
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