The Evolution of Fibromyalgia, Its Concepts, and Criteria

Abstract

Fibromyalgia developed in the 1950s from a substrate of difficult to explain regional and widespread pain mixed with symptoms of psychosocial distress. Controversies regarding psychological issues were common. Multiple criteria arose to define the disorder, but each identified a different set of patients. The identification of widespread pain as a criterion changed the nature of the disorder by effectively eliminating regional pain as a component condition. The easy-to-measure and relatively reliable widespread pain criterion then came to define the disorder. In the primary care community, diagnostic criteria were largely ignored, and a substantial fraction of diagnosed patients with lower pain scores, particularly women and those with high non-pain symptom scores, were diagnosed. Non-pain symptoms were added back to the fibromyalgia definition and criteria in 2010. Recognition grew that fibromyalgia fit the description of a functional somatic disorder. The idea of fibromyalgia as a primary pain disorder with a neurobiological basis contended with fibromyalgia as a broader biopsychosocial disorder. It is increasingly recognized that fibromyalgia represents a dimensional, non-binary condition and that features of fibromyalgia extend to persons who do not satisfy the criteria. Severity assessments are now available but rarely used. The course of fibromyalgia is not well studied, and improvement and remission criteria have not been successfully defined. The future of fibromyalgia as a discrete disorder remains uncertain as features of fibromyalgia are increasingly observed in patients with multiple different medical conditions.

Keywords: diagnosis; fibromyalgia; fibromyalgia criteria; misdiagnosis; somatic syndromes.

Figure 1. WPI and SSS scores in the German general population.

The horizontal line at an SSS of 5 and the vertical line at a WPI of 7 represent fibromyalgia diagnostic level requirements. Red dots are fibromyalgia-positive cases. Blue dots are cases not qualifying because of the 2016 widespread pain requirement. Yellow dots are fibromyalgia-negative cases with high symptom scores. Tan dots are fibromyalgia-negative cases with high WPI scores. Green dots are fibromyalgia-negative cases with low symptom and WPI scores. The diagonal line represents a PSD value of 12 [1]. WPI: widespread pain index; SSS: symptom severity scale; PSD: polysymptomatic distress

Figure 2. WPI and SSS scores in 3,276 US primary care patients.

The horizontal line at SSS of 5 and the vertical line at WPI of 7 represent fibromyalgia diagnostic-level requirements. Red dots are fibromyalgia criteria-positive cases, as diagnosed by physicians. In the right upper quadrant, red dot cases satisfied the criteria. In the left upper quadrant, red dots cases did not satisfy the fibromyalgia criteria. Blue dots are fibromyalgia-positive cases that satisfy the criteria but were not diagnosed by physicians. Tan dots are fibromyalgia criteria and physician-negative cases with high WPI but low SSS. Yellow dots are fibromyalgia criteria and physician-negative cases with high SSS and low WPI. White dots are fibromyalgia criteria and physician-negative cases with low SSS and low WPI. Only cases in the right upper quadrant satisfy fibromyalgia 2016 criteria. The dashed diagonal line represents the line where the PSD score is 12 [2]. WPI: widespread pain index; SSS: symptom severity scale; PSD: polysymptomatic distress; FM: fibromyalgia

Figure 3. The relation between clinical severity as measured by the SF-36 PCS and the PSD scale in the NDB.

The lower curve represents kernel density estimation of the PSD distribution. With increasing PSD values, which become less common, more abnormal PCS values are seen. The blue line represents the predicted values of SF-36 and 95% confidence intervals. SF-36: Short Form-36; PCS: Physical Component Score; PSD: polysymptomatic distress; NDB: National Data Bank for Rheumatic Diseases

Figure 4. Association of PSD with selected status and outcomes in the National Health Interview Survey.

PSD: polysymptomatic distress Reprinted after permission from PLoS One: Walitt B, Nahin RL, Katz RS, Bergman MJ, Wolfe F: The prevalence and characteristics of fibromyalgia in the 2012 National Health Interview Survey. PLoS One. 2015, 10:e0138024. 10.1371/journal.pone.0138024 [28].

Figure 5. Association of PSD with a comorbid condition in patients with fibromyalgia in the NDB.

Predicted percentage with comorbidity at levels of PSD. PSD: polysymptomatic distress; NDB: National Data Bank for Rheumatic Diseases; GU: genitourinary; GI: gastrointestinal; w/o IBS: without irritable bowel syndrome Modified from Wolfe F, Ablin J, Guymer EK, Littlejohn GO, Rasker JJ: The relation of physical comorbidity and multimorbidity to fibromyalgia, widespread pain, and fibromyalgia-related variables. J Rheumatol. 2020, 47:624-31. 10.3899/jrheum.190149 [52].

Figure 6. Association of PSD scores with clinical status and life events in the German population epidemiology study.

Lines are predicted mean values and 95% confidence intervals. PSD: polysymptomatic distress; BMI: body mass index Modified from Wolfe F, Brähler E, Hinz A, Häuser W: Fibromyalgia prevalence, somatic symptom reporting, and the dimensionality of polysymptomatic distress: results from a survey of the general population. Arthritis Care Res (Hoboken). 2013, 65:777-85. 10.1002/acr.21931 [1].

Figure 7. The relation between WPI and five symptom scales in the NDB.

WPI: widespread pain index; NDB: National Data Bank for Rheumatic Diseases; NRD: patients with non-inflammatory disorders; RA: rheumatoid arthritis patients; NDB all: count of all somatic symptoms; NDB non-pain, non-FM: all symptoms that are not related to pain or fibromyalgia variables; NDB non-pain: symptoms not related to pain; SSS8: short symptom scale-8 [56]; PHQ-15: Patient Health Questionnaire-15 scale [55]

Figure 8. The relation between WPI and four symptom scales on the x-axis in NDB patients.

The red horizontal line occurs at a WPI of 7, the level where high WPI scores begin [56]. WPI: widespread pain index; NDB: National Data Bank for Rheumatic Diseases; NRD: patients with non-inflammatory disorders; RA: rheumatoid arthritis patients; NDB all: count of all somatic symptoms; NDB non-pain, non-FM: all symptoms that are not related to pain or fibromyalgia variables; NDB non-pain: symptoms not related to pain; SSS8: short symptom scale-8 [57]; PHQ-15: Patient Health Questionnaire-15 scale

Figure 9. Venn diagram of FM 2016 and PHQ-15 at PHQ-15 of >9. N = 6,571 in the NDB.

FM: fibromyalgia; PHQ-15: Patient Health Questionnaire-15 scale [55]; NDB: National Data Bank for Rheumatic Diseases