Concomitant fibromyalgia in rheumatoid arthritis is associated with the more frequent use of biological therapy

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SCIENCE
Concomitant fibromyalgia in rheumatoid arthritis is associated with the more frequent use of biological therapy
Key Take-Away: 
  • Concomitant fibromyalgia in patients with rheumatoid arthritis is associated with a higher Disease Activity Score (DAS28) due to subjective parameters and with the more frequent use of biological treatments.
  • The mean DAS28 in the fibromyalgia group was 4.4 as compared to 2.9 in the non- fibromyalgia group.

Fibromyalgia (FM) is a prototypical central pain syndrome, characterized by widespread pain and tenderness, often accompanied by disturbed sleep, fatigue, cognitive impairment and emotional distress. The rate of co-morbid FM in individuals with classical autoimmune or rheumatic diseases, including rheumatoid arthritis (RA), is reported to be between 12-17%. 

ABSTRACT: 
Background: 

Fibromyalgia (FM) is a prototypical central pain syndrome, characterized by widespread pain and tenderness, often accompanied by disturbed sleep, fatigue, cognitive impairment and emotional distress. The rate of co-morbid FM in individuals with classical autoimmune or rheumatic diseases, including rheumatoid arthritis (RA), is reported to be between 12-17%. These rates are much higher than the reported prevalence of FM in the general population (1–4%).

In the clinical management of RA patients, the composite 28-joint Disease Activity Score (DAS28) is commonly used to assess disease activity and inform treatment decisions. There is evidence that concomitant FM among RA patients increases DAS28 significantly, mainly based on high contributions from patients’ global assessment and tender joint count. The RA patients with concomitant FM are at risk of further intensive treatment of RA despite a lack of objective parameters of inflammation such as a high swollen joint count or increased levels of C-reactive protein (CRP).

Rationale behind research

  1. RA patients with concomitant FM are at risk of further intensive treatment of RA despite a lack of objective parameters of inflammation such as a high swollen joint count or increased levels of C-reactive protein (CRP)
  • Objective

To compare the 28-joint Disease Activity Score (DAS28) and its components in patients with rheumatoid arthritis with and without concomitant fibromyalgia, and to investigate the use of biological treatment in the two groups.

Methods: 

 

Study outcomes

  • Questionnaires developed to diagnose FM were handed out among RA patients during their planned visits.
  •  Each patient’s DAS28 were obtained from the DANBIO (Danish adults treated with biologics) registry which covers demographic data and data on patients’ medical treatment, disease duration, serological and radiological status were retrieved from patients’ files.
  • Time-points
    • Efficacy : Baseline and up to 4 months
Results: 

 

Outcome: 

  • No significant differences found regarding disease duration, age, gender and serological status
  • Of RA patients with concomitant FM, 64% vs 32% of RA patients without concomitant FM were treated with biological therapy (p = 0.002).
  • Mean DAS28 in the FM group was 4.4 than to 2.9 in non-FM group (p < 0.001).
  • Elevated DAS28 in the FM group resulted from a high tender joint count (p = 0.003) and a high visual analogue scale (VAS)-global score (p < 0.001). Erosions were more frequent in the non-FM group (p = 0.04).

 

Conclusion: 

Concomitant FM in patients with RA is associated with a higher DAS28 due to subjective parameters and with more frequent use of biological treatments. This raises the question of whether the more frequent use of biologics in these patients is justified by inflammation, or is instead due to persistent pain and other centrally mediated symptoms.

In our study, patients with concomitant FM had a significantly higher DAS28. This difference between groups was mainly due to contributions from subjective parameters, while no difference in CRP or swollen joint count was observed. Several other studies reported that, RA patients with concomitant FM, DAS28 may be increasingly dominated in patient who will not respond to anti-inflammatory therapy.

Scand J Rheumatol 2015; 1–4
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