medwireNews: Fibromyalgia could contribute to patients with rheumatoid arthritis (RA) not reaching remission, concludes research presented at the Annual European Congress of Rheumatology (EULAR) 2017 in Madrid, Spain.
The conclusion is based on the finding that fibromyalgia in patients with RA was associated with significantly increased levels of RA disease activity, according to the Disease Activity Score at 28 joints (DAS28) and swollen and tender joint counts, over a 10-year follow-up period.
Of 636 patients initially enrolled in the Oslo RA register (ORAR) in 1994, 488 were re-examined in 1999, at which point 40 were diagnosed with fibromyalgia based on having a tender point count of at least 11. These patients were predominantly female and had slightly lower body mass index than patients without fibromyalgia.
Synonymous with fibromyalgia, muscle tenderness, fatigue, abdominal pain, and difficulty concentrating were all worse in RA patients with the condition, compared with 440 RA patients without, with average scores on a visual analog scale (VAS) of 5.9 versus 3.2, 6.6 versus 4.4, 3.7 versus 1.9, and 2.9 versus 1.7, respectively.
But what Sella Proven, from Diakonhjemmet Hospital in Oslo, Norway, highlighted in her presentation was that the patients with fibromyalgia also had significantly increased RA disease activity compared with those without the condition.
Scores on the DAS28 were 5.3 versus 4.4, and the swollen- and tender-joint counts were 9.8 versus 6.8, and 13.3 versus 7.4, respectively. There were also significant differences for VAS pain and disease activity scores.
This cross-sectional association also existed in longitudinal analyses of 192 of the patients who were followed up again 10 years later in 2009.
After adjusting for age, gender, body mass index, and DAS28 measured in 1999, the patients with fibromyalgia according to tender point score had a significantly higher RA Disease Activity Index (RADAI) score at the 10-year follow-up than those without fibromyalgia and this was also true when fibromyalgia was diagnosed according to a Fibromyalgia Score of 13 and above versus below 13.
The presence of fibromyalgia, according to either tender points or Fibromyalgia Score, was also found to be a negative predictor of RA remission (RADAI inactivity) at 10 years in a logistical regression model, reducing the likelihood by between 9 and 16%.
“We thus conclude that the presence of fibromyalgia in patients with RA is associated with significantly higher levels of RA disease activity both in the cross-sectional and longitudinal perspectives,” said Proven.
Speaking to medwireNews, she advised that clinicians “always consider fibromyalgia as a concomitant disease in patients with RA who are not reaching remission and do not have swollen joints,” adding that patients could not be reaching remission “purely, or largely, because of their tender joints.”
By Lucy Piper
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