Prevalence and impact of fibromyalgia on disease activity in a sample of Iraqi patients with rheumatoid arthritis

Abstract

IntroductionRheumatoid arthritis (RA) is a chronic systemic autoimmune inflammatory disease. Fibromyalgia (FM) is a common diffuse pain syndrome in several rheumatic diseases. This study aimed to find the prevalence of FM in RA patients and to explore its impact on the disease activity of RA patients.Material and methodsA total of 170 RA patients diagnosed according to the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria for RA were enrolled in this cross-sectional study. Age, gender, body mass index, marital status, educational level, occupation, smoking history, disease duration, and medications used were reported. Fibromyalgia was diagnosed by using the fibromyalgia criteria 2016 revision. The disease activity of RA patients was measured by using the clinical disease activity index (CDAI) and disease activity score-28 (DAS28).ResultsThe mean age of fibromyalgia syndrome (FMS) patients was 51.263 ±11.531 years, and for non-FMS patients it was 48.469 ±13.932 years. FM was present in 57 (42.7%) RA patients, among whom the prevalence of FMS among female patients was 36.4%, which was significantly higher than that among male patients, at 6.3% (p = 0.015). FM significantly increased the disease activity measured by DAS28 ( = 0.241, p = 0.001) and by CDAI ( = 0.359, p < 0.001). Female gender and functional class of patients with RA positively increase the disease activity DAS28 ( = 0.142, p = 0.032;  = 0.396, p > 0.001), while only functional class increased the disease activity measured by CDAI ( = 0.373, p > 0.001).ConclusionsThe occurrence of FM in RA patients was common, and there was significant positive correlation between FMS severity and RA disease activity.