The epidemiology of fibromyalgia. Workshop of the Standing Committee on Epidemiology European League Against Rheumatism (EULAR), Bad Säckingen, 19-21 November 1992

Temporomandibular Disorders and Fibromyalgia: A Narrative Review

Temporomandibular disorder (TMD) and fibromyalgia (FM) have some clinical characteristics in common, for instance the chronic evolution, the pathophysiology incompletely understood and a multifactorial genesis. The incidence and the relationship between TMD and FM patients are the aims of this review. A MEDLINE and Pubmed search was performed for the key words “temporomandibular disorder” AND “fibromyalgia” from 2000 to present. A total of 19 papers were included in our review, accounting for 5449 patients. Ten studies, reporting a total of 4945 patients with TMD, showed that only 16.5% of these patients had diagnosis of FM, whereas 12 studies, reporting a total of 504 patients with FM, demonstrated that 77.0% of these patients had diagnosis of TMD. A comorbid relationship exists between TMD and FM. The complexity of both diseases shows the importance of a multimodal and interdisciplinary.

Profiles in fibromyalgia: algometry, auditory evoked potentials and clinical characterization of different subtypes

The heterogeneity found in fibromyalgia (FM) patients has led to the investigation of disease subgroups, mainly based on clinical features. The aim of this study was to test the hypothesis that clinical FM subgroups are associated with different underlying pathophysiological mechanisms. Sixty-three FM patients were classified in type I or type II, according to the Fibromyalgia Impact Questionnaire (FIQ), and in mild/moderate versus severe FM, according to the severity of three cardinal symptoms considered in the American College of Rheumatology (ACR) 2010 criteria (unrefreshed sleep, cognitive problems and fatigue). To validate the subgroups obtained by these two classifications, we calculated the area under the receiver operating characteristic curves for various clinical variables and for two potential biomarkers of FM: Response to experimental pressure pain (algometry) and the amplitude/intensity slopes of the auditory evoked potentials (AEPs) obtained to stimuli of increasing intensity. The variables that best discriminated type I versus type II were those related to depression, while the indices of clinical or experimental pain (threshold or tolerance) did not significantly differ between them. The variables that best discriminated the mild/moderate versus severe subgroups were those related to the algometry. The AEPs did not allow discrimination among the generated subsets. The FIQ-based classification allows the identification of subgroups that differ in psychological distress, while the index based on the ACR 2010 criteria seems to be useful to characterize the severity of FM mainly based on hyperalgesia. The incorporation of potential biomarkers to generate or validate classification criteria is crucial to advance in the knowledge of FM and in the understanding of pathophysiological pathways.

Prevalence of fibromyalgia in France: a multi-step study research combining national screening and clinical confirmation: The DEFI study (Determination of Epidemiology of FIbromyalgia)

BACKGROUND

Fibromyalgia is a common disease, but little is known on its real prevalence in France. This epidemiological study aimed to assess fibromyalgia (FM) prevalence in the French metropolitan population, based on a multi-step sampling analysis, combining national screening and clinical confirmation by trained specialists.

METHODS

a sampling method on the entire national territory was used: patients over 18 years of age accepting to take part in the study were contacted by telephone using the LFES Questionnaire, a screening test for FM. The, for patients detected by the LFESQ, a visit with a FM-trained rheumatologist was proposed to confirm FM, based on 1990 ACR criteria. Each detected patient completed the following self-questionnaires: SF36, HADS, stress VAS, Co-morbidities and Regional pain score.

RESULTS

3081 patients were contacted in 5 representative French regions, of which 232 patients were screened for FM. A fibromyalgia diagnosis was then confirmed by rheumatologist in 20 cases (17 female and 3 male, 56.9 ± 13.2 years). The final estimated FM prevalence was 1.6 (CI95: 1.2%; 2.0%). No significant difference was detected between the patients accepting (CS+) and refusing (CS-) rheumatologist visit for the SF36 score, regional pain score, stress VAS scale and co-morbidities. In patients detected for FM by the LFESQ, we found a statistically significant decrease in quality of life and a statistically significant increase in stress level in patients with a confirmed diagnosis (FM+) (6.3 ± 1.9) compared to patients with an invalidated diagnosis (FM-) (4.4 ± 2.8; p = 0.007). The study also demonstrated a significant association, independently of ACR criteria, between the diagnosis of FM and several factors such as regional pain score > 10, elevated stress level, low SF36 scale score and presence of gastro-intestinal disorder co-morbidities.

CONCLUSION

Fibromyalgia is a common condition; the 1.6% prevalence calculated in the French population in our study corroborates the figures published in the European literature. Our results also suggest that criteria such as regional pain score, stress level or SF36 quality of life, could represent useful tools in fibromyalgia diagnosis.

Longterm Therapeutic Response to Milnacipran Treatment for Fibromyalgia. A European 1-Year Extension Study Following a 3-Month Study

Objective.

This double-blind, 1-year extension study investigated the longterm efficacy and safety of milnacipran 100, 150, and 200 mg/day in the treatment of fibromyalgia (FM) in completers of a 3-month European double-blind lead-in study of milnacipran 200 mg/day versus placebo.

Methods.

A total of 468 patients with FM successfully completing the lead-in study were either blindly maintained on milnacipran 200 mg/day (MLN200:MLN200, n = 198) or (if previously receiving placebo) rerandomized to milnacipran 100 mg/day (PBO:MLN100, n = 91), 150 mg/day (PBO:MLN150, n = 92), or 200 mg/day (PBO:MLN200, n = 87) for an additional 12 months (including a 4-week dose escalation). The main efficacy endpoint was a 2-measure composite responder rate (relative to lead-in study baseline) incorporating the weekly-recall pain score recorded on a visual analog scale and the Patient Global Impression of Change score. A panel of other assessments including the Fibromyalgia Impact Questionnaire explored the multidimensional aspects of FM. Descriptive analyses using the last observation carried forward approach were performed.

Results.

At the 1-year endpoint, the proportion of composite responders (relative to the lead-in study baseline) ranged from 27.5% (PBO:MLN100) to 35.9% (MLN200:MLN200), and had increased from the extension study baseline by 15.2% (PBO:MLN150) to 20.7% (PBO:MLN200 and MLN200:MLN200). At endpoint, an improvement from both baselines was shown in all groups on pain, fatigue, sleep, and quality of life measures. Up to 1 year, all doses of milnacipran were safe and well tolerated. The most common drug-related adverse events were hyperhidrosis and nausea.

Conclusion.

Over 1 year, milnacipran 100, 150, and 200 mg/day exhibited sustained and safe therapeutic effects on predominant symptoms of FM. Registered as trial no.NCT00757731.

The pathophysiology, diagnosis and treatment of fibromyalgia

Research in fibromyalgia has increased understanding of the possible genetic and environmental factors that could be involved in the etiology of fibromyalgia. There is now substantial evidence for augmentation of central pain processing in fibromyalgia. Because the clinical presentation of fibromyalgia is heterogeneous, treatment recommendations must be individualized for each patient. The rapid growth of trials in fibromyalgia in recent years has resulted in new evidence-based approaches to pharmacological and nonpharmacological treatment.

Reliability of ACR criteria over time to differentiate classic fibromyalgia from nonspecific widespread pain syndrome: a 6-month prospective cohort study

American College of Rheumatology (ACR) 1990 criteria, initially introduced to classify fibromyalgia (FM) syndrome, has gained popularity in research and clinical grounds for diagnostic purposes. The objectives of this study were designed to assess the consistency of ACR criteria against the time in classifying FM. This was a prospective cohort study performed in a multidisciplinary pain clinic from October 2002 to June 2005. Patients who were clinically suspected of having FM and had a normal screening laboratory evaluation were scheduled for dolorimetry. Those found to have 6 or more tender points were considered eligible and labeled as either classic or atypical FM if they did or did not, respectively, fulfil ACR criteria. The 2 groups were assessed using the Fibromyalgia Impact Questionnaire (FIQ) and compared using baseline characteristics. We reassessed dolorimetric exam and FIQ 6 months later. Of 91 patients who participated in this study,70 completed the follow-up. Of them, 34 (49%) patients were identified as atypical, and 36 (51%) were labeled as classic FM. At first visit, the classic FM group had higher scores on sleep quality, stiffness, anxiety, depression, and total FIQ score (p\0.05) but not for other variables. At 6 months, there was no significant difference between the 2 groups in all measured variables. Labeling shift from classic to atypical FM and vice versa occurred at a rate of 36.1 and 32.4%, respectively. This study showed the ACR 1990 criteria was not able to consistently classify affected patients with FM syndrome within a group of patients having nonspecific body pain and multiple tender points over 6 months of follow-up.

A European Multicenter Randomized Double-blind Placebo-controlled Monotherapy Clinical Trial of Milnacipran in Treatment of Fibromyalgia

Objective.

This randomized, double-blind, placebo-controlled, multicenter study investigated the efficacy and safety of milnacipran in the treatment of fibromyalgia (FM) in a European population.

Methods.

Outpatients diagnosed with FM according to 1990 American College of Rheumatology criteria (N = 884) were randomized to placebo (n = 449) or milnacipran 200 mg/day (n = 435) for 17 weeks (4-week dose escalation, 12-week stable dose, 9-day down-titration), followed by a 2-week posttreatment period. The primary efficacy criterion was a 2-measure composite responder analysis requiring patients to achieve simultaneous improvements in pain (≥ 30% improvement from baseline in visual analog scale, 24-hour morning recall) and a rating of “very much” or “much” improved on the Patient Global Impression of Change scale. If responder analysis was positive, Fibromyalgia Impact Questionnaire (FIQ) was included as an additional key primary efficacy measure.

Results.

At the end of the stable dose period (Week 16), milnacipran 200 mg/day showed significant improvements from baseline relative to placebo in the 2-measure composite responder criteria (p = 0.0003) and FIQ total score (p = 0.015). Significant improvements were also observed in multiple secondary efficacy endpoints, including Short-Form 36 Health Survey (SF-36) Physical Component Summary (p = 0.025), SF-36 Mental Component Summary (p = 0.007), Multidimensional Fatigue Inventory (p = 0.006), and Multiple Ability Self-Report Questionnaire (p = 0.041). Milnacipran was safe and well tolerated; nausea, hyperhidrosis, and headache were the most common adverse events.

Conclusion.

Milnacipran is an effective and safe treatment for pain and other predominant symptoms of FM. Registered as trial no. NCT00436033.

Clinical expression profiles of complex regional pain syndrome, fibromyalgia and a-specific repetitive strain injury: More common denominators than pain?

PURPOSE

To systematically evaluate and compare the clinical manifestations, disease course, risk factors and demographic characteristics of Complex Regional Pain Syndrome type 1 (CRPS), fibromyalgia (FM) and a-specific Repetitive Strain Injury (RSI).

METHOD

A literature search was performed using terms related to the aforementioned topics and diseases. Only original clinical studies that included at least 20 subjects were eligible.

RESULTS

Fifty-nine studies on CRPS, 73 on FM and 7 on a-specific RSI were identified. The diseases show similarities in age distribution, male-female ratio, pain characteristics and sensory signs and symptoms. Motor, autonomic and trophic changes are frequently reported in CRPS, but only occasionally in FM and RSI. Systemic symptoms are found in patients with CRPS and FM, and in a subgroup of patients with RSI. In all three disorders, symptoms usually start locally, but may spread to other body regions later, which, in the case of FM, is a prerequisite for diagnosis. Disease onset is always, usually, or occasionally of traumatic origin in RSI, CRPS and FM, respectively. Anxiety and depression are more frequent in patients compared to controls, but probably not very different from patients with other pain conditions or chronic diseases.

CONCLUSIONS

Apart from some obvious differences between CRPS, FM and RSI, the similarities are conspicuous. The common features of CRPS, FM and a-specific RSI may suggest that a common pathway is involved, but until patients with these type of symptoms are assessed with a uniform assessment procedure, a thorough comparison cannot be made. A systematic evaluation of patients with a suspected diagnosis of CRPS, FM or RSI, may lead to a better appreciation of the differences and similarities in these diseases and help to unravel the underlying mechanisms.

Clinical features of the stomatognathic involvement in fibromyalgia syndrome: a comparison with temporomandibular disorders patients

Several studies have reported an involvement of the stomatognathic system in the course of fibromyalgia (FM) similar to that which characterizes temporomandibular disorders (TMD). The aim of this study was to investigate and compare the clinical features of stomatognathic dysfunction in patients with FM and TMD. Ninety-three FM patients underwent an assessment according to the RDC/TMD guidelines. Prevalence of the different RDC/TMD diagnoses and some clinical parameters of FM patients were compared with those of 181 patients affected by TMD. Seventy-four (79.6%) FM patients presented at least one RDC/TMD diagnosis and showed lower mean maximum voluntary and passive mouth opening values than TMD patients. Moreover, 34 FM patients presented with trigger and/or tender points. Results of the present study confirm the high rate of involvement of the stomatognathic system in the course of FM and support the need for a careful multidisciplinary approach to patients with TMD, including the rheumatologist.

Neuroendocrine and immune aspects of fibromyalgia

Fibromyalgia is a form of non-articular rheumatism characterised by long term (>3 months) and widespread musculoskeletal aching, stiffness and pressure hyperalgesia at characteristic soft tissue sites, called soft tissue tender points. The biophysiology of fibromyalgia, however, has remained elusive and the treatment remains mainly empirical. This article reviews the neuroendocrine-immune pathophysiology of fibromyalgia. There is no major evidence that fibromyalgia is accompanied by activation of the inflammatory response system, by immune activation or by an inflammatory process. There is some evidence that fibromyalgia is accompanied by some signs of immunosuppression, suggesting that immunomodifying drugs could have potential in the treatment of fibromyalgia. Recent trials with cytokines, such as interferon-alpha, have been undertaken in patients with fibromyalgia. Immunotherapy with these agents, however, may induce symptoms reminiscent of fibromyalgia and depression in a considerable number of patients. Lowered serum activity of prolyl endopeptidase (PEP), a cytosolic endopeptidase that cleaves peptide bonds on the carboxyl side of proline in proteins of relatively small molecular mass, may play a role in the biophysiology of fibromyalgia through diminished inactivation of algesic and depression-related peptides, e.g. substance P. Trials with PEP agonists could be worthwhile in fibromyalgia. The muscle energy depletion hypothesis of fibromyalgia is supported by findings that this condition is accompanied by lowered plasma levels of branched chain amino acids (BCAAs), i.e. valine, leucine and isoleucine. Since there is evidence that BCAA supplementation decreases muscle catabolism and has ergogenic values, a supplemental trial with BCAAs in fibromyalgia appears to be justified.

Classification, epidemiology, and natural history of fibromyalgia

Fibromyalgia (FM), also known as fibromyalgia syndrome (FMS) and fibrositis, is a common form of nonarticular rheumatism that is associated with chronic generalized musculoskeletal pain, fatigue, and a long list of other complaints. Some have criticized the classification of FM as a distinct medical entity, but existing data suggest that individuals meeting the case definition for FM are clinically somewhat distinct from those with chronic widespread pain who do not meet the full FM definition. Clinic studies have found FM to be common in countries worldwide; these include studies in specialty and general clinics. The same is true of general population studies, which show the prevalence of FM to be between 0.5% and 5%. Knowledge about risk factors for FM is limited. Females are at greater risk, and risk appears to increase through middle age, then decline. Although some authors claim that an epidemic of FM has been fueled by an over-generous Western compensation system, there are no data that demonstrate an increasing incidence or prevalence of FM; moreover, existing data refute any association between FM prevalence and compensation. Claims that the FM label itself causes illness behavior and increased dependence on the medical system also are not supported by existing research. This article reviews the classification, epidemiology, and natural history of FM.

Prevalence of fibromyalgia and chronic widespread pain

OBJECTIVE

To explore the prevalence of fibromyalgia and chronic widespread musculoskeletal pain in a general population using the criteria of the American College of Rheumatology from 1990.

DESIGN

Structured interview and clinical examination, including tender-point count and pain threshold measured with a dolorimeter, of subjects with suspected chronic widespread musculoskeletal pain.

SETTING

The general population in south-west Sweden 1995-1996.

SUBJECTS

303 individuals with suspected chronic widespread pain were identified in a previously defined cohort containing 2425 men and women aged 20-74 years. 202 individuals were invited and 147 agreed to participate.

MAIN OUTCOME MEASURES

Tenderpoint count, pain threshold and prevalence of chronic widespread pain and fibromyalgia.

RESULTS

The prevalence of fibromyalgia was estimated to 1.3% (95% CI 0.8-1.7; n = 2425) and that of all chronic widespread pain to 4.2% (95% CI 3.4-5.0; n = 2425). The mean pain threshold measured with a dolorimeter was lower in subjects with chronic widespread pain (p < 0.01) and correlated with the number of tender points (r = -0.59, p < 0.01) but could not be used to distinguish the subjects with fibromyalgia.

CONCLUSION

Compared to other studies, fibromyalgia and chronic widespread musculoskeletal pain seemed to be relatively rare conditions in the south-west of Sweden.

The occurrence and impact of generalized pain

A major problem with estimating the impact of chronic generalized pain is that the term remains undefined. It appears to encompass several distinct clinical entities, including rheumatoid arthritis and fibromyalgia, which can exist alone or together in a given individual. Nonetheless, chronic generalized pain appears to have a sizable impact on both the individual and society. Although little is known about causal relationships, demographic risk factors for chronic generalized pain are female sex, age in the forties and fifties, lower income, lower education, and being divorced or separated. Chronic generalized pain affects the individual in several ways, including physical and psychological distress, losses of function, quality of life, employment and income, and prolonged litigation for many. Its impact on society includes increased utilization of health care resources, loss of work productivity, disability and insurance costs, costs of litigation and social policy. Future research into the impact of chronic generalized pain must begin by defining this term in a way that is both valid in construct and convenient to use. Research is also warranted to develop and validate diagnostic tools that may better distinguish various subsets of chronic generalized pain, both to better understand the pathological processes involved and to allow for estimates of the relative contribution of each subset to societal costs.

The immune-inflammatory pathophysiology of fibromyalgia: increased serum soluble gp130, the common signal transducer protein of various neurotrophic cytokines

Fibromyalgia is a chronic, painful musculoskeletal disorder characterized by widespread pain, pressure hyperalgesia, morning stiffness and by an increased incidence of depressive symptoms. The etiology, however, has remained elusive. The aim of the present study was to examine the inflammatory response system (IRS) in fibromyalgia. Serum interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R), sgp130, sIL-1R antagonist (IL-1RA) and sCD8 were determined in 33 healthy volunteers and in 21 fibromyalgia patients, classified according to the American College of Rheumatology criteria. Severity of illness was measured with several pain scales, dolorimetry and the Hamilton Depression Rating Scale (HDRS). Serum sgp130 was significantly higher and serum sCD8 significantly lower in fibromyalgia patients than in healthy volunteers. Serum sIL-6R and sIL-1RA were significantly higher in fibromyalgia patients with an increased HDRS score (> or = 16) than in normal volunteers and fibromyalgia patients with a HDRS score < 16. In fibromyalgia patients, an important part of the variance in sCD8 (50.3%) and IL-1RA (19.3%) could be explained by the HDRS score; 74.3% of the variance in sIL-6R was explained by the combined effects of pain symptoms and the HDRS score; and 25.9% of the variance in serum sgp130 was explained by stiffness. The results support the contention that pain and stiffness in fibromyalgia may be accompanied by a suppression of some aspects of the IRS and that the presence of clinically significant depressive symptoms in fibromyalgia is associated with some signs of IRS activation.