Indian Journal of Rheumatology

: 2022  |  Volume : 17  |  Issue : 2  |  Page : 129--135

Effects of fibromyalgia syndrome in patients with diffuse systemic sclerosis: Evaluation with 2010 American college of rheumatology criteria set

Ayse Ayan1, Hanife Hale Hekim2, Sebahat Yaprak Cetin3,  
1 Department of Rheumatology; Department of Physical Medicine and Rehabilitation, Medicine School, Antalya Training and Research Hospital of Health Sciences University, Antalya, Turkey
2 Department of Physical Medicine and Rehabilitation, Medicine School, Antalya Training and Research Hospital of Health Sciences University, Antalya, Turkey
3 Department of Physiotherapy and Rehabilitation, Faculty of Health Sciences, Akdeniz University, Antalya, Turkey

Correspondence Address:
Dr. Sebahat Yaprak Cetin
Department of Physiotherapy and Rehabilitation, Faculty of Health Sciences, Akdeniz University, Antalya


Backgrounds: The aim of this study was to evaluate the frequency of fibromyalgia syndrome (FMS) according to the 2010 FMS criteria and to investigate its effects on quality of life in patients with diffuse systemic sclerosis (SSc). Methods: The study included 44 SSc patients with a mean age of 52.84 ± 13.35 years and 96 healthy adults with a mean age of 53.43 ± 14.67 years. The symptom severity scale, fibromyalgia impact questionnaire, beck depression and anxiety inventory, and the short form (SF)-36 were used for evaluations in the study. FMS was detected in 27 patients with SSc (62.79%) and 13 health controls (13.5%). Results: When SF-36 subscales were compared, a statistically significant difference was found in favor of the fibromyalgia patient group in respect of physical function, physical role difficulty, mental role, and pain scores (P: 0.04-0.00). Conclusion: Our results showed that FMS frequency was increased in patients with diffuse SSc and that FMS significantly affected the quality of life. In addition, the anxiety and depression levels were also increased in SSc patients with FMS. It can be recommended to assess patients with SSc for FMS during routine clinic examinations.

How to cite this article:
Ayan A, Hekim HH, Cetin SY. Effects of fibromyalgia syndrome in patients with diffuse systemic sclerosis: Evaluation with 2010 American college of rheumatology criteria set.Indian J Rheumatol 2022;17:129-135

How to cite this URL:
Ayan A, Hekim HH, Cetin SY. Effects of fibromyalgia syndrome in patients with diffuse systemic sclerosis: Evaluation with 2010 American college of rheumatology criteria set. Indian J Rheumatol [serial online] 2022 [cited 2022 Jul 4 ];17:129-135
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Systemic sclerosis (SSc) is a multisystem disease characterized by immune activation, microvascular disease, and fibroblast dysfunction, which is thought to occur as a result of a poorly understood, complex interaction between genetic and environmental factors, leading to fibrotic changes in the skin and some internal organs.[1] It is characterized by the deposition of collagen and other matrix components in the skin and some internal organs. From health assessment questionnaire (HAQ) surveys, it has been shown to cause disability with increasing frequency over time.[2]

Musculoskeletal pain is a common complaint (40%–80%) in patients with SSc. Joint complaints are frequently (24%–96%) present and clinically manifest as arthralgia, flexion contractures, and less often, true arthritis.[3],[4] A previous study reported narrowing in joint space in and erosive disease in 4% of SSc patients.[5] Arthralgia develops as a result of immobility and contractures, with fibrosis around tendons and other periarticular structures. While painful arthralgia is frequently observed in patients with SSc, true inflammatory arthritis is rarely observed.[6] Inflammatory proliferative tenosynovitis and tendon ruptures are often detected. Although pain cannot be sufficiently localized to a particular anatomical area, there are several musculoskeletal pain syndromes that can be detected in patients with SSc,[7] including tendonitis, polyarthritis, rheumatoid arthritis, bursitis, and fibromyalgia.[7],[8],[9],[10] Although there are several studies on syndromes other than fibromyalgia syndrome (FMS), the relationship between FMS and SSc has not been clearly understood. As with other connective tissue diseases, fibromyalgia is not considered to be rare in SSc. There are a few studies[11],[12],[13] on this subject, and with the exception of one, the tender point count (TPC) in the American College of Rheumatology (ACR) 1990 FMS diagnostic criteria set were evaluated. However, it should be kept in mind that TPC may not provide objective data, as fibrosis can be difficult to determine and there may be inter-observer variability in TPC.

FMS is characterized by chronic, nonarticular diffuse musculoskeletal pain and sensitivity.[14],[15] It affects almost every race and ethnic group, all socioeconomic classes, and all age groups, including children. It is seen more frequently in women than in men (by 9-folds).[16] The FMS prevalence has been reported to range between 0.5% and 4% in developed countries.[17] Despite increasing frequency by advancing age, it is most frequently seen between the ages of 20 and 55 years.[17] Until 2010, the 1990 ACR classification criteria were used for diagnosis,[18] which includes widespread pain for more than 3 months and somatic pain in ≥11 tender points (of 18) when the pressure of 4 kg was applied with the finger. In 2010, the ACR published new criteria, which may be an alternative method in clinical practice, without sensitive points, but including the widespread pain index (WPI) and symptom severity scale (SSS).[19] This new set of criteria alone is not affected by pain and is based on patient reporting. Therefore, it seems clinically more significant for the determination of the origin of pain in autoimmune diseases. To the best of our knowledge, there is only one study in the literature in which SSc patients have been evaluated using the 2010 FMS criteria set.[11] In the study, the incidence of FMS in SSc patients was reported as 23.7% according to the ACR 2010 criteria set.[11] However, no assessment was performed for comorbid psychiatric diseases regarding medication used and patients with secondary Sjögren's syndrome, which can cause widespread pain, were also included in the study. Therefore, it was aimed to evaluate the FMS frequency based on 2010 FMS criteria and to investigate its effect on the quality of life in our study which only included patients with diffuse SSc alone.



Initially, the study initially enrolled patients who were followed up with the diagnosis of diffuse SSc rheumatology clinic of our hospital. The patients were diagnosed by a rheumatologist according to the 2013 ACR-/EULAR classification criteria. All patients who presented to the outpatient clinic with diffuse SSc were included in the study. Overall, 53 patients with diffuse SSc were enrolled while six patients declined to participate in the study and 3 patients did not complete the questionnaires. Thus, the final analyses included 44 patients who met the inclusion criteria and completed questionnaires. All patients were was treated according to EULAR recommendations based on the organ involvement and clinical presentation.[20] As all the patients who met the inclusion criteria were female, 96 age-matched healthy female volunteers with matched for age and education levels and without any additional disease were employed as the control group. All participants gave written informed consent before participation. In all participants, demographic characteristics such as age, education period, and body mass index (BMI) were recorded. In addition, all patients were questioned for digital ulcer (DU), pulmonary arterial hypertension (PAH), interstitial lung disease (ILD), and duration of the disease. The study was approved by the local ethics committee.

The inclusion criteria were defined as follows:

Definitive diagnosis of SSc with diffuse involvementWillingness for participantsNo known depression and/or any other psychiatric illnessNo additional disease other than scleroderma (diabetes mellitus, hypertension, etc.)No known additional rheumatic diseasesNo regular use of steroids, antidepressants, antiepileptic agents, or nonsteroidal anti-inflammatory drugs (NSAID) the exclusion criteria are as follows: Patients with active disease and Valentini criteria score of 3[21]Those who failed to complete all questionnaires.

Rheumatologic evaluations

All patients were evaluated by a rheumatologist with detailed history and physical examination. In the scleroderma group, patients were evaluated for comorbid rheumatic diseases. The healthy control group was evaluated for rheumatic diseases (undiagnosed connective tissue diseases and additional rheumatologic diseases) that may accompany to exclude secondary FMS exclusion. For the diagnosis of FMS, the 2010 ACR FMS diagnostic criteria set was used independently by two physicians (AA and HH).[19] A fibromyalgia effect questionnaire was administered to individuals diagnosed with FMS in the patient and healthy control groups.[20] All subjects including SSc patients and controls were evaluated with the Beck depression inventory (BDI) and Beck anxiety inventory (BAI). The short form (SF-36) was used to evaluate the quality of life in all patients.

Evaluation tools

The 2010 ACR FMS diagnostic criteria set is evaluated using the WPI and SSS.[19] The WPI is a self-rated scale. The WPI score ranges from 0 to 19 based on painful areas within the prior week. The regions are classified as right shoulder, left shoulder, right hip (gluteal region), left hip (gluteal region), left chin, right chin, left upper arm, left lower arm, right upper arm, right lower arm, left upper leg, left lower leg, right upper leg, right lower leg, chest, neck, abdomen, upper back, and lower back. The SSS assesses weakness, tired awakening, cognitive functions, muscle pain, weakness, irritable bowel syndrome, memory problems, headache, abdominal pain, numbness, dizziness, insomnia, depression, constipation, irritability, dry mouth, and other somatic symptoms. Each item is scored using a 4-points Likert scale (0 = none, 1 = light, 2 = medium, 3 = heavy). The total score ranges from 0 to 12.

The fibromyalgia impact questionnaire (FIQ) is used to evaluate the functional status, disease progression, and outcomes. The validity study of the FIQ was conducted by Bennett et al.[22] The questionnaire consists of 20 items related to physical function, work status, depression, anxiety, sleep, pain, stiffness, fatigue, and well being.

The BAI was developed by Beck et al. in 1988, as a self-reported scale to measure the severity of anxiety symptoms experienced. There are 21 items related to subjective anxiety and physical symptoms, each of which is scored between 0 and 3 with Likert-type responses. High scores indicate higher level of anxiety. The Turkish validity and reliability study was made by Ulusoy et al.[23]

The BDI assesses the risk for depression as well as the level and changes in the severity of depressive symptoms in patients. The BDI is a self-reported assessment scale including 21 items which are rated using a 4-point Likert scale. The validity and reliability of the BDI in Turkish have been proven.[24]

The SF-36 was developed to measure the quality of life. Validity and reliability studies were conducted for the Turkish version of the scale. The SF-36 includes a health transition item and assesses 4 physical health domains and 4 mental health domains. The SF-36 scales can be summarized into physical component summary and mental component summary scores. Each SF-36 scale is scored from 0 to 100, with higher scores representing better health.[25]

Statistical analysis

Data obtained in the study were analyzed statistically using SPSS for Windows vn. 22.00 software (IBM, Chicago, IL). Descriptive statistics are presented as frequency, percentage, mean (mean), standard deviation and median (median), minimum (min), maximum (max) values. The Shapiro–Wilks test was used to assess the conformity of the data to normal distribution. In the analysis of the difference quantitative data between two groups, the Mann–Whitney U test was used for variables with skewed data, while the Independent Samples t-test was used data with normal distribution. Variables showing a significant difference in univariate analysis were included, and Pearson correlation analysis was used for the relationship with independent risk factors in FMS prevalence, where the sample number was small and the data fit the normal distribution. A value of P < 0.05 was considered statistically significant.


There were no male subjects in the patient group (n = 44) and the control (n = 96). The mean age was 52.84 ± 13.35 years in the patient group and 53.43 ± 14.67 years in the control group [Table 1]. Disease duration was 72.43 ± 56.63 months in the patient group. The characteristics of the patient group are shown in [Table 2].{Table 1}{Table 2}

FMS was detected in 27 (62.79%) individuals in the patients group and 13 (13.5%) individuals in the control group (P < 0.001). The BDI, BAI, FMS criteria score and FIQ scores were similar in individuals with FMS in the patient and control groups [P > 0.05, [Table 3]]. In the comparison of the PAH, DU, and ILD parameters, no significant difference was found between the patients with and without FMS [P > 0.05, [Table 4]]. When the SF-36 sub-parameters were compared, a statistically significant difference was found in physical function (P: 0.01), physical role difficulty (P: 0.04), mental role (P: 0.01), and pain scores (P: 0.00) favoring the patients without FMS [Table 4].{Table 3}{Table 4}

When the relationship between FMS presence and age, gender, BMI, PAH, DU, ILD, BDI, and BAI in patients with SSc was examined, statistically significant correlations were found with the BDI and BAI scores [P: 0.00, [Table 5]].{Table 5}


In this study, FMS was detected in 62.79% of the patients with diffuse SSc. Compared to studies involving patients with all forms of SSc, the rate found in our study was higher than those reported in the literature. In the FMS patient group, the BDI and BAI scores were higher in patients with FMS than those without. A positive correlation was found between FMS presence and BDI and BAI. It was found that there were no differences between SSc patients with and without FMS regarding PAH, ILD, DU. The SF-36 scores were found to be worse in physical function, physical role, and pain sub-parameters in the patients with FMS. It seemed that FMS had significant effects on the quality of life of patients regardless of disease activity.

It was shown that the depression and anxiety disorders were increased in FMS patients compared to both healthy controls and those with chronic painful conditions.[26] Several opinions have been proposed to explain how depression and anxiety disorders show comorbidity in FMS.[26] Some authors proposed that psychiatric disorders can occur reactively to FMS while others proposed that psychiatric disorders could trigger FMS symptoms or that there are relationships in the pathophysiology of FMS and psychiatric disorders.[27] The common physiopathogenetic factor may be pathological changes associated with various neurotransmitter systems shown to be involved in both FMS and psychiatric disorders. Dopamine and serotonin transmission as well as gene polymorphisms that affect the levels of these neurotransmitters are among these common biological factors.[28] Regardless of underlying mechanisms, prolonged stress leads to the release of pro-inflammatory cytokines in the brain. The elevated cytokine levels lead to predisposition for both psychiatric diseases and an increase in the perception of pain.[29],[30] In addition, FMS coexistence with consequences of psychiatric disorders reflected in clinical practice should also be underlined. Common symptoms in both diseases can cause confusion in diagnosis; thus clinicians should be careful in this context. In addition, the stress, and sudden changes in the emotional-state experienced by the patient after the diagnosis of SSc may also trigger FMS. In the current study, the BDI and BAI scores were higher in the SSC patients with FMS than those without. Nevertheless, large-scale studies are needed to clarify the relationship between SSc and FMS. SSc is a systemic disease that significantly impairs quality of life due to severe organ involvement. FMS is also a condition that significantly impairs quality of life and causes significant disability. Therefore, it was thought that FMS must be assessed in SSc patients. The detection of FMS will prevent unnecessary treatment and improve the quality of life in the patient. According to the 1990 ACR criteria, clinical examination is subjective, and different results can be reached by different physicians on tender points. Moreover, diffuse SSc patients have significant skin involvement, comprising a distinct problem. In this context, by including the patient in the self-reporting, the new 2010 ACR criteria set provides a good assessment opportunity for diffuse SSc patients. It has been reported that the ACR 2013 alternative criteria significantly reduced the diagnosis rate. Therefore, we did not use these criteria in the current study.[31]

As with all diseases, stress is one of the most important factors in SSc pathogenesis. FMS is important both for the identification of concomitant psychiatric disorders and establishing the SSc treatment plan. Depression observed in FMS patients is thought to have different characteristics. It has been reported that negative thinking, the feeling of helplessness, and anxiety are more common.[32] It was shown that the patients with FMS have difficulties in understanding and recognizing their own emotions and coping with these emotions.[33]

The most common symptom in patients with fibromyalgia is pain. In addition to pain, fatigue, decreased quality of life, sleep disturbance, cognitive problems, morning stiffness, depression, and anxiety are frequently seen.[34] The most important component that impairs quality of life is pain in FMS. Prolonged pain results in physical, psychosocial, and social disorders. Therefore, psychosocial, behavioral, and educational interventions are as important as medical therapy in the treatment.[35] In this study, the SF-36 quality of life scores was found to be worse in SSc patients with FMS than in SSc patients without FMS. A multidisciplinary approach is necessary for effective FMS treatment. Arthritic symptoms in SSc will often require analgesic therapy (such as NSAID, paracetamol, low-dose glucocorticoid), but it should also be remembered that glucocorticoids increase the risk of renal complications in SSc patients. Although there is no specific treatment for arthritis in patients with SSc, the principles for rheumatoid arthritis are generally adopted.[10] Methotrexate, hydroxychloroquine, and glucocorticoid are shown to provide benefits. However, if FMS is not diagnosed, the patient's joint complaints can be thought to be related to the clinical activation of SSc, resulting in overtreatment. The patient will be exposed to toxic drugs and the symptoms will not be relieved.

The treatment of physical and mental symptoms seen in FMS is possible only with a multidimensional approach including the concurrent use of pharmacological and nonpharmacological therapies. The combined use of psycho-education, exercise recommendations, and cognitive-behavioral psychotherapy methods enhances the likelihood of success compared to drug treatments alone.[36] As mentioned above, SSc is a progressive disease capable of serious organ involvement. Clinicians mostly concentrate on protecting major organs, so in daily practice, there may be difficulty in evaluating the locomotor system involvement and it may even be overlooked. Based on the results of this study, it can be recommended that follow-up should be taken in terms of the presence of accompanying FMS to improve the quality of life of patients with SSc.

In this study, another important finding was that no difference was determined between SSC patients with and without FMS regarding the presence of PAH, IAH, and DU which are major involvements in the primary disease. However, the quality of life scores differed significantly between the two groups. This finding showed that FMS has more impact than disease activity on quality of life. This result supports Wolfe, who defined a strong association with FMS regarding pain levels and disability in all rheumatic diseases.[37] Wolfe stated that SSc patients with accompanying FMS do not have a more severe primary disease phenotype in the context of organ involvement. In other words, while FMS contributes significantly to disability, it should not be used as an indicator of primary disease severity.

In the current study, the frequency of FMS in both the patient group and the healthy control group was higher compared to findings in the literature. Previous studies have reported that the prevalence of FMS is increased by advancing age, so the results of the current study may be due to the higher mean age in the control group.[38] In addition, there was no male patient in the current study because the inclusion criteria were applied strictly and there is a female preponderance in SSc. This study has some limitations including limited sample size, female preponderance (no male patient), and higher mean age in the study population. In addition, the ACR classification criteria set would also be used simultaneously. Despite these limitations, this study can be deemed as important since it is the first study that includes only patients with diffuse SSc and uses the 2010 FMS criteria set. The results will also contribute to efforts for improving the quality of life of patients with SSc. However, there is a need for further, large-scale studies including patients of all ages and genders to provide better insight into the topic. In addition, future studies also may determine and compare the frequency of FMS in other rheumatological diseases.


The results of this study demonstrated that the frequency of FMS was increased in patients with diffuse SSc and it significantly affected the quality of life. Anxiety and depression levels were also seen to be increased in SSc patients with FMS. In the SSc patient group with and without FMS, no difference was found in terms of PAH, ILD, and DU. Thus, FMS seems to significantly affect patients' quality of life regardless of disease activity. It can be recommended to asssess patients with SSc for FMS during routine clinic examinations; to establish treatment plans accordingly; and to developed to strategies to improve the quality of life and reduce pain (personal physiotherapy, psycho-education, exercise recommendations, and cognitive-behavioral psychotherapy, etc.,) in this patient population.

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Conflicts of interest

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1Gupta RA, Fiorentino D. Localized scleroderma and systemic sclerosis: Is there a connection? Best Pract Res Clin Rheumatol 2007;21:1025-36.
2Schnitzer M, Hudson M, Baron M, Steele R, Canadian Scleroderma Research Group. Disability in systemic sclerosis – A longitudinal observational study. J Rheumatol 2011;38:685-92.
3Blocka KL, Bassett LW, Furst DE, Clements PJ, Paulus HE. The arthropathy of advanced progressive systemic sclerosis. A radiographic survey. Arthritis Rheum 1981;24:874-84.
4Misra R, Darton K, Jewkes RF, Black CM, Maini RN. Arthritis in scleroderma. Br J Rheumatol 1995;34:831-7.
5La Montagna G, Baruffo A, Tirri R, Buono G, Valentini G. Foot involvement in systemic sclerosis: A longitudinal study of 100 patients. Semin Arthritis Rheum 2002;31:248-55.
6Tuffanelli DL, Winkelmann RK. Systemic scleroderma, A clinical study of 727 cases. Arch Dermatol 1961;84:359-71.
7Clements PJ, Allanore Y, Khanna D, Singh M, Furst DE. Arthritis in systemic sclerosis: Systematic review of the literature and suggestions for the performance of future clinical trials in systemic sclerosis arthritis. Semin Arthritis Rheum 2012;41:801-14.
8Clements P. Management of musculoskeletal involvement in systemic sclerosis. Curr Treatm Opt Rheumatol 2016;2:61-8.
9Arslan Tas D, Erken E, Sakalli H, Yucel AE. Evaluating hand in systemic sclerosis. Rheumatol Int 2012;32:3581-6.
10Avouac J, Clements PJ, Khanna D, Furst DE, Allanore Y. Articular involvement in systemic sclerosis. Rheumatology (Oxford) 2012;51:1347-56.
11Perrot S, Peixoto M, Dieudé P, Hachulla E, Avouac J, Ottaviani S, et al. Patient phenotypes in fibromyalgia comorbid with systemic sclerosis or rheumatoid arthritis: Influence of diagnostic and screening tests. Screening with the FiRST questionnaire, diagnosis with the ACR 1990 and revised ACR 2010 criteria. Clin Exp Rheumatol 2017;35 Suppl 105:35-42.
12Sarah El-Rabbat M, Mahmoud NK, Gheita TA. Clinical significance of fibromyalgia syndrome in different rheumaticdiseases: Relation to disease activity and quality of life. Rheumatol Clin 2018;14:285-9.
13Ostuni P, Botsios C, Sfriso P, Bertagnin A, Cozzi F, Doria A, et al. Prevalenceand clinical features of fibromyalgia in systemic lupus erythematosus, systemicsclerosis and Sjögren's syndrome. Minerva Med 2012;93:203-9.
14Balkarli A, Sengül C, Tepeli E, Balkarli H, Cobankara V. Synaptosomal-associated protein 25 (Snap-25) gene polymorphism frequency in fibromyalgia syndrome and relationship with clinical symptoms. BMC Musculoskelet Disord 2014;15:191.
15Chakrabarty S, Zoorob R. Fibromyalgia. Am Fam Physician 2007;76:247-54.
16White K. Sex Differences in Chronic Widespread Pain and Fibromyalgia: Do they Exist and Why? XX vs XY 2003;1:1.
17Wolfe F, Ross K, Anderson J, Russell IJ, Hebert L. The prevalence and characteristics of fibromyalgia in the general population. Arthritis Rheum 1995;38:19-28.
18Wolfe F, Symthe HA, Yunus MB, Bennett RM, Bombardier C, Goldenberg DL, et al. The American College of Rheumatology 1990 criteria fort the classification of fibromyalgia. Arthritis Rheum 1990;33:160-72.
19Wolfe F, Clauw DJ, Fitzcharles MA, Goldenberg DL, Katz RS, Mease P, et al. The American College of Rheumatology preliminary diagnostic criteria for fibromyalgia and measurement of symptom severity. Arthritis Care Res (Hoboken) 2010;62:600-10.
20Kowal-Bielecka O, Fransen J, Avouac J, Becker M, Kulak A, Allanore Y, et al. Update of EULAR recommendations for the treatment of systemic sclerosis. Ann Rheum Dis 2017;76:1327-39.
21Valentini G, Silman AJ, Veale D. Assessment of disease activity. Clin Exp Rheumatol 2003;21:S39-41.
22Bennett RM, Friend R, Jones KD, Ward R, Han BK, Ross RL. The Revised Fibromyalgia Impact Questionnaire (FIQR): Validation and psychometric properties. Arthritis Res Ther 2009;11:R120.
23Ulusoy M, Şahin N, Erkmen H. Turkish version of beck anxiety inventory: Psychometric properties. J Cogn Psychother 1998;12:163-72.
24Hisli N. Validity and reliability of beck depression inventory for university students. Psychol J 1989;7:3-13.
25Koçyiğit H, Aydemir Ö, Fişek G, Ölmez N, Memiş A. Reliability and validity of the Turkish version of short form-36 (SF-36). J Med Treat 1999;12:102-6.
26Thieme K, Turk DC, Flor H. Comorbid depression and anxiety in fibromyalgia syndrome: Relationship to somatic and psychosocial variables. Psychosom Med 2004;66:837-44.
27Marcus DA, Bernstein C, Rudy TE. Fibromyalgia and headache: An epidemiological study supporting migraine as part of the fibromyalgia syndrome. Clin Rheumatol 2005;24:595-601.
28Bradley LA. Pathophysiologic mechanisms of fibromyalgia and its related disorders. J Clin Psychiatry 2008;69 Suppl 2:6-13.
29Maier SF. Bi-directional immune-brain communication: Implications for understanding stress, pain, and cognition. Brain Behav Immun 2003;17:69-85.
30Anisman H, Merali Z. Cytokines, stress and depressive illness: Brain-immune interactions. Ann Med 2003;35:2-11.
31Türk AÇ. Old and new criteria for the diagnosis of fibromyalgia: Comparison and evaluation. Ankara Med J 2019;1:83-95.
32Ercolani M, Trombini G, Chattat R, Cervini C, Piergiacomi G, Salaffi F, et al. Fibromyalgic syndrome: Depression and abnormal illness behavior. Multicenter investigation. Psychother Psychosom 1994;61:178-86.
33Güleç H, Sayar K, Topbaş M, Karkucak M, Ak I. Alexithymia and anger in women with fibromyalgia syndrome. Turk Psikiyatri Derg 2004;15:191-8.
34Mease P, Arnold LM, Bennett R, Boonen A, Buskila D, Carville S, et al. Fibromyalgia syndrome. J Rheumatol 2007;34:1415-25.
35Sarzi-Puttini P, Buskila D, Carrabba M, Doria A, Atzeni F. Treatment strategy in fibromyalgia syndrome: Where are we now? Semin Arthritis Rheum 2008;37:353-65.
36Clauw DJ. Pharmacotherapy for patients with fibromyalgia. J Clin Psychiatr 2008;69 Suppl 2:25-9.
37Wolfe F. Fibromyalgianess. Arthrit Rheum 2009;61:715-6.
38Topbas M, Cakirbay H, Gulec H, Akgol E, Ak I, Can G. The prevalence of fibromyalgia in women aged 20-64 in Turkey. Scand J Rheumatol 2005;34:140-4.