Prevalence of fibromyalgia in patients with ankylosing spondylitis

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.