Prevalence of Fibromyalgia in Patients with Ankylosing Spondylitis

Ankylosing spondylitis (AS) is defined as a chronic inflammatory disorder which influences the axial skeletal system, resulting in pain and functional disabilities. Fibromyalgia (FM) is one of the main causes of generalized pain and can coexist with other disorders. Few researchers have found association between FM and AS. The present study obtained data regarding the prevalence of FM in patients with AS. Methods: A total of 40 (30 male and 10 female) patients with AS, diagnosed according to the modified New York criteria, were studied. Two stage classification process was applied to determine the presence of FMS in AS patients: Stage 1: diffuse wide spread pain questionnaire to a sample of 40 (30 male and 10 female) patients with AS. Stage 2: all patients with wide spread pain were examined for 18 tender points. A sample of 40 (30 male and 10 female) healthy individuals were examined as controls. Results: 10 patients met the criteria of FMS, with a prevalence of 25.0% among patients with AS, of whom 80.0% were women. Conclusions: FMS is more prevalent in patients with AS than in the general population, and the prevalence is comparable with other musculoskeletal disorders. There is a trend for an increased frequency of FMS in females with AS. AS patients with FMS may benefit from psychological evaluation as a part of their treatment. Further study is needed to correlate between FMS and AS disease activity of patients.