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Year : 2014  |  Volume : 7  |  Issue : 3  |  Page : 338-341  

Prevalence of fibromyalgia in patients with ankylosing spondylitis

1 Department of Rheumatology, Faculty of Medicine, Imam Khomeini Hospital, Mazandaran University of Medical Sciences, Sari, Iran
2 Department of Nephrology, Faculty of Medicine, Imam Khomeini Hospital, Mazandaran University of Medical Sciences, Sari, Iran

Date of Web Publication18-Mar-2014

Correspondence Address:
Aref Hosseinian Amiri
Department of Rheumatology, Faculty of Medicine, Imam Khomeini Hospital, Mazandaran University of Medical Sciences, Sari
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0975-2870.128977

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Introduction: Ankylosing spondylitis (AS) is a chronic inflammatory disease that affects the peripheral and axial skeletal system, causing pain, arthritis, low back pain and functional incapacity. Questionnaires are used to assess disease activity bath ankylosing spondylitis disease activity index (BASDAI) to measure the effect of AS on patient's life quality, functional incapacity bath ankylosing spondylitis functional index (BASFI); and Ankylosing Spondylitis quality of life (ASQoL). Fibromyalgia (FM) is one of the most common causes of generalized pain and fatigability and can coexist with other diseases; it can be assessed by the FM impact questionnaire (FIQ). There are few studies that demonstrated correlations between FM and AS. The present study obtained data regarding the epidemiologic profile of patients with AS and FM and evaluated the prevalence of FM in patients with AS. The FM influence on BASDAI, BASFI and ASQoL test scores was assessed. Materials and Methods: A total of 36 patients with AS, diagnosed according to the modified New York criteria, were studied. Clinical and functional assessment was performed and BASDAI, BASFI and ASQoL tests were applied. Patients with a diagnosis of FM were evaluated through the FIQ. Results: Seven patients met the criteria for FM; thus a FM prevalence of 19.4% was observed among patients with AS. FM was more prevalent among women (2.5:1). Age at disease onset (AS) was 24.3 years. The human leukocyte antigen-B27 antigen was positive in most of them (83.2%). When comparing BASDAI, BASFI and ASQoL test means, it was observed that values are significantly higher (P < 0.01) among patients with FM. We concluded that the coexistence of FM with AS is associated with disease activity aspects including pain, as well as functional disability and quality of life.

Keywords: Ankylosing spondylitis, bath ankylosing spondylitis disease activity index, bath ankylosing spondylitis functional index, fibromyalgia

How to cite this article:
Amiri AH, Sedighi O. Prevalence of fibromyalgia in patients with ankylosing spondylitis. Med J DY Patil Univ 2014;7:338-41

How to cite this URL:
Amiri AH, Sedighi O. Prevalence of fibromyalgia in patients with ankylosing spondylitis. Med J DY Patil Univ [serial online] 2014 [cited 2021 Dec 3];7:338-41. Available from:

  Introduction Top

Ankylosing spondylitis (AS) is a chronic inflammatory disease that affects mainly the skeletal system specially the spine and in some patients peripheral joints and can result in stiffness and progressive axial skeletal system functional limitation and extra articular manifestations. [1],[2] AS is more frequent in young adults, with age at onset generally ranging from 20 to 40 years and is more prevalent in Caucasians and human leukocyte antigen (HLA)-B27-positive individuals and the male sex (3:1). [2],[3] It is part of the spondyloarthropathy complex, which is strongly correlated with HLA-B27, whose presence varies from 80% to 98% of the cases respectively. [4] The initial clinical presentation includes inflammatory low back pain associated with morning stiffness. [1],[2] AS In the spine causes vertebral fusion, osteoporosis, ligament ossifications and resulting in a remodeled and weakened vertebral column, with a strong tendency toward fractures and deformation. [1],[5] The enthesopathy of spondyloarthropaties including AS are characterized by inflammation at the tendon and/or ligament insertions on bones and affect mainly the calcaneal tendon insertion and plantar fascia. [1] The modified New York criteria, with clinical and radiographic features, are used to confirm AS diagnosis. The presence of a clinical as well as of a radiographic criterion is necessary to attain AS diagnosis. [6] In 1994, Garret et al. presented a questionnaire for evaluation of AS an activity. [7] The bath ankylosing spondylitis disease activity index (BASDAI) test is a six-question questionnaire comprising domains related to fatigue, spinal pain, pain and articular symptoms, pain related to enthesis involvement and two questions related to the quality and amount of morning stiffness. The score is measured using visual analog scales from 0 to 10 (0 = good; 10 = poor). It is currently considered one of the most important tools for use in clinical assays. [8] In 1994, Calin et al. published the bath ankylosing spondylitis functional index (BASFI), a questionnaire that aims were assessing for functional limitation in patients with AS. [9] The test includes eight items related to activities of daily living and two items that measure patient skill when dealing with everyday routine. [9] Many countries have already carried out the validation of this method. [10],[11] Questionnaires like the Ankylosing Spondylitis Quality of Life (ASQoL) questionnaire have been used for assessment of quality of life (QoL) as an end-point measurement in clinical studies. The test comprises 18 questions with yes or no answers, which result in a score from 0 to 18, with the highest score being associated with a worse QoL. [8],[12] Fibromyalgia (FM) is one of the most common causes of generalized musculoskeletal pain. Its etiology is not known, but it is believed to be an inflammatory process. It is considered to be a pain amplification syndrome, associated with a central nervous system sensitization mechanism. [13],[14] It is more frequent in females and most patients are between 35 and 50 years of age. The physical examination typically does not show synovitis and/or other symptoms indicating inflammatory disease; the main characteristic is the presence of tender points identified on palpation. [14],[15] FM can coexist with other rheumatologic diseases, such as psoriatic arthritis (24%), [16] rheumatoid arthritis (25%), [13] systemic lupus erythematosus (30%) [13] and Crohn's disease (49%). [17] The diagnosis is essentially a clinical one and is based on the identification of tender points and the absence of symptoms or laboratory findings that can indicate an inflammatory or degenerative disease. In this sense, the inflammatory activity tests, muscle enzymes and electromyography results are normal. [13],[15] The American College of Rheumatology (ACR) criteria are used in research. [14] There have been some studies that demonstrated a correlation between FM and AS. [18] The present study aimed at obtaining data regarding the epidemiologic profile of patients with AS and FM and identifying FM prevalence in patients with AS. It also aimed at comparing the functional indices and assessing whether the coexistence of the FM picture can interfere with the disease activity evaluation (BASDAI), functional assessment (BASFI) and ASQoL patient test scores.

  Materials and Methods Top

The study was evaluated 36 patients with AS diagnosed according to the modified New York criteria, treated at the Rheumatology Outpatient Clinic of Rasoul Hospital of Tehran, from April 2008 to December 2011. Patients that presented another concomitant rheumatologic disease that could justify the presence of chronic generalized pain were excluded from the study. All patients gave their free and informed consent to participate in the study, which was approved by the Ethics Committee in Research of the Hospital. A cross-sectional, observational epidemiologic study of prevalent cases was carried out. The patients answered a questionnaire that included the following information: Age, sex, symptom onset date and family history concerning the presence of AS in first-degree relatives. Diagnosis of FM confirmed by one well-trained psychologist and one rheumatologist according the 1990 ACR classification criteria for FM. Data from the medical files were collected regarding the HLA-B27 antigen screening. Disease activity assessment was carried out by applying the BASDAI questionnaire; functional assessment by applying the BASFI questionnaire and patient quality of life was evaluated through the ASQoL. Subsequently, the patients were assessed regarding the presence of FM according to the criteria established by the ACR and cases were considered positive in the presence of the two concomitant criteria. The patients were divided into two groups: With and without FM. The BASDAI, BASFI and ASQoL test scores of both groups were compared by the Student's t-test and Wilcoxon's test.

  Results Top

The epidemiologic data of the 36 patients is shown in [Table 1]. Of these, 83.3% were males and 16.7% were females (a male: Female ratio of 4.98:1). Of the 36 assessed patients, 7 (19.4%) met the ACR criteria for FM, of whom 2 (28.5%) were males and 5 (71.5%) were females. FM prevalence was 19.4% among the AS patients, with a female: Male ratio of 2.5:1. Patients' mean age was 39.57 (standard deviation [SD] = 11.58), ranging from 19 to 69.3 years. Mean age at symptom onset was 24.3 years (SD = 11.71). Mean symptom duration was 15.39 years (SD = 9.84). Only 13.2% of the patients had a positive family history for spondyloarthritis. Of the 36 assessed patients, 30 (83%) of patients were positive for HLA-B27 antigen. The comparative data of the two subgroups are shown in [Table 2].
Table 1: Epidemiologic and clinical data of 36 study participants with ankylosing spondilytis diagnosis

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Table 2: BASDAI, BASFI and ASQoL test comparative data in patients with and without FM

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  Discussion Top

Epidemiological data of the present study corroborate the data found in the literature. Mean age at disease onset in our patients was 24.3 years, which is within the 20-40 range, that is, symptom onset typically at the young adult age range. Prevalence of AS was higher in the male sex (5:1) and the male to female ratio was a little higher when compared with literature data (3:1). The HLA-B27 antigen was positive in most of them (83.2%). [19]

Although a low incidence of positive family history for spondyloarthritis was observed in most patients the genetic factors classically contribute to a higher susceptibility to disease development. It was observed that the risk of developing AS is much higher (10-20-fold higher) among relatives of patients with positive HLA-B27, when compared with the general population with positive HLA-B27. [20]

A single study identified the FM prevalence among patients with AS. [18] Aloush et al. studied a group of 36 patients with an AS diagnosis, of which 18 were males and 18 females. The authors confirmed the FM diagnosis in 50% of the females, but did not confirm it in any of the men. The investigators observed that patients that presented the two diseases concomitantly had more severe functional impairment, which resulted in higher scores at the BASDAI and BASFI tests, when compared to the scores of patients with only one disease. An important bias was present and raised questions regarding whether the presence of FM could influence the result of the functional assessment tests: The diagnosis of FM was established in the group of a female patient's only. [18] It is known that AS manifestation is different between genders, having a worse prognosis among men.

In our study, 36 patients were assessed and FM prevalence was 19.4%; in this group of patients, 28.5% were males and 71.5% were females. We evaluated a more different sample between men (28.5%) and women (71.5%) among those individuals with FM. We confirmed significantly higher scores at the BASDAI (P < 0.001 at Student's t-test and P = 0.002940 at Wilcoxon's test) and BASFI (P < 0.001 at Student's t-test and P = 0.001992 at Wilcoxon's test) tests. In addition, we compared the ASQoL test results and also observed higher scores (P = 0.0019 at Student's t-test and P = 0.001884 at Wilcoxon's test) among patients with FM. Heikkilä et al., [21] stressed the correlations found between the two diseases, in spite of the predominance of each one of them at different sexes and in different ages. When assessed by laboratory tests, only AS presents characteristics of an inflammatory disease. However, from a clinical perspective, both lead to a decrease in functional and work capacity in a very similar way. [21],[22],[23] It is noteworthy the fact that FM and AS share many symptoms. The diagnosis of AS is based on the presence of chronic axial pain associated with morning stiffness, which are common complaints in FM. [14] Fatigue, sleep disorder, anxiety and depression are significant complaints in FM and also often reported by patients with AS. These problems are strongly associated with pain. [24],[25],[26],[27]

Currently, the indication for the use of biological agents such as anti TNF agents in AS is based on the activity index, among others. [28] Based on our results, we suggest that before biological agents are prescribed, patients with AS should be assessed regarding the possibility of concomitant FM and those showing positive criteria should be adequately treated and reassessed.

Limitation of the present study is the lack of a control group and presence of possible bias for performing of this study only in one hospital. Nearly 19.4% prevalence of FM was verified among patients with AS, with the concomitance being more frequent in females. In addition, the data showed that the concomitant presence of FM are associated with the symptoms of disease activity, functional impact and compromise the quality of life of patients with AS.

  References Top

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  [Table 1], [Table 2]

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