Comparison of ankylosing spondylitis patients with and without fibromyalgia syndrome according to the disease activation scores and response to treatment

The aim of this study was to investigate the association of fibromyalgia (FM) syndrome with ankylosing spondylitis (AS) and to compare the AS patients with and without FM according to the disease activity, clinical and laboratory findings, and response to treatment. Between September 2016 and September 2020, a total of 511 patients (312 males, 119 females; mean age: 43.0±11.2 years; range, 18 to 77 years) who were diagnosed with AS were retrospectively analyzed. Age, sex, disease duration, disease onset age, and extra-articular findings were recorded. Medical treatments used by the patients for the treatment of AS and FM were noted. The erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), human leukocyte antigen-B27 (HLA-B27) status, and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score (ASDAS) with ESR (ASDAS-ESR) and ASDAS-CRP values were recorded. The frequency of FM in AS patients was 23.2%. Totally, 75.4% of the FM patients were female. The HLA-B27 positivity, extra-articular involvement frequency, disease duration, and acute phase reactants levels were similar between AS patients with and without FM (p=0.118, p=0.154, p=0.829, p=0.113, and p=0.763, respectively). The AS patients with FM had lower rates of achieving remission or low disease activity, compared to those without FM. The mean of all three disease activity scores between these two groups was also higher in the AS patients with FM (p