Evaluation of Fibromyalgia Syndrome and Its Effect on Quality of Life in Rheumatoid Arthritis

Rheumatoid arthritis is a chronic, autoimmune, systemic inflammatory disease with a prevalence of approximately 1%. With a lifetime development rate of 3.6%, rheumatoid arthritis is seen 1.7% more in women than in men. Synovial joints are the primary involvement site of the disease, and due to insufficient control of the disease, irreversible joint damage and disability may develop. Although there are no diagnostic criteria for rheumatoid arthritis, ACR / EULAR 2010 classification criteria are frequently used in diagnosis. Symptom duration, number of swollen joints, acute phase reactants and serology are used in these criteria.

Fibromyalgia syndrome is characterized by chronic widespread pain, fatigue, exercise disorders and cognitive impairment. Although the prevalence of fibromyalgia syndrome in the general population is between 2-4%, it is one of the most common conditions encountered by rheumatologists. The prevalence of fibromyalgia increases with age and is more common in women, with a female: the male ratio between 2:1 to 30:1, depending on which diagnostic criteria are applied.

The first approved classification criteria for fibromyalgia syndrome was developed in 1990 by the American College of Rheumatology (ACR). These criteria include chronic widespread pain for more than 3 months and evaluation of 18 sensitive points. Although it was developed for classification, it was also used as a diagnostic criterion by most rheumatologists. Updated diagnostic criteria excluding sensitive point evaluation were published by ACR in 2010. Common pain index and symptom severity score were used in these criteria. In 2011, these criteria were modified with criteria including the physician's assessment of somatic symptoms. The 2010 and 2011 criteria evaluate symptom severity and 'being fibromyalgia' using the common pain index and symptom severity scale.

There are 2 main groups in fibromyalgia, these are; primary fibromyalgia and secondary fibromyalgia due to a comorbid disease. Primary fibromyalgia is more common and characterized by local pain that initially spreads later. Differential diagnosis is difficult in these individuals because of the common symptoms of rheumatological diseases such as pain and fatigue. Centralized pain may develop with inflammatory arthritis or as a result of the disease. Chronic inflammation can mediate central pain from peripheral pain that can cause symptoms in fibromyalgia. In animal models, pro-inflammatory cytokines such as Tumor Necrosis Factor and Interleukin-6 have been associated with abnormal central pain processing and widespread pain sensitivity.

In Rheumatoid Arthritis(RA) patients, the presence of fibromyalgia syndrome was found 2.1 times more frequently in patients who were Rheumatoid Factor negative than those who were positive, and 3.0 times more frequently in patients who were positive in anti-citrullinated protein antibody (ACPA) seronegative. It is thought that in seronegative patients, clinicians may be less likely to diagnose RA or attribute the RA prodroma symptom as fibromyalgia syndrome. Also alternatively, fibromyalgia syndrome may be the underlying diagnosis in some seronegative cases. In another study investigating the presence of secondary fibromyalgia syndrome in patients with early inflammatory arthritis; it was found that ACPA negative patients had fibromyalgia syndrome more frequently than seropositive patients. The authors hypothesized that this might be caused by ACPA-positive patients were treated more aggressively and disease control was reached earlier, or clinicians were more likely to diagnose fibromyalgia in ACPA-negative patients.

A treat to target strategy is recommended in RA disease management. This approach suggests close monitoring of disease activity and treatment change in cases where the goal is not achieved. In randomized studies, with a treat to target strategy, patients have been found to have a decrease in radiological progression, in disease activity, an increase in physical function and quality of life.

The prevalence of fibromyalgia in rheumatoid arthritis patients was found to be 5-52% in meta-analyzes due to the heterogeneity of fibromyalgia criteria used in studies.When the 2010/2011 criterion was used, the prevalence was found to be higher than the 1990 criteria. (24% vs 18%)Despite this heterogeneity, a strong relationship was found between DAS28 and comorbid fibromyalgia. As DAS28, disease activity index such as SDAI( simplified disease activity index) and CDAI (clinical disease activity index) were found to be correlated with comorbid fibromyalgia.

This study, it was aimed to evaluate the effect of secondary fibromyalgia syndrome, which is frequently found in rheumatoid arthritis and characterized by symptoms such as fatigue and widespread pain, on rheumatoid arthritis disease activation and patients' quality of life.