medwireNews: Results of a systematic review and meta-analysis suggest that a substantial proportion of patients with chronic inflammatory arthritis have concomitant fibromyalgia, which may influence measures of disease activity.
Nicola Goodson (University of Liverpool, UK) and team found that the prevalence rate of fibromyalgia “varied considerably” from 4.9% to 52.4% among 29 studies of patients with rheumatoid arthritis (RA), giving a pooled prevalence rate of 21.0%.
The overall prevalence of fibromyalgia was 13.0% (range 4.11–25.0%) in eight studies of patients with ankylosing spondylitis (AS), and 18.0% (range 9.6–27.2%) in six studies involving those with psoriatic arthritis (PsA).
These results indicate that “[f]ibromyalgia is very common in chronic inflammatory arthritis,” say the authors, noting that the reported prevalence in the general population is around 1–5%.
Because fibromyalgia is “strongly associated with female gender,” they suggest that variation in fibromyalgia prevalence between diseases may reflect differences in the proportion of men and women with each condition.
“RA affects more women, PsA occurs in men and women almost equally and AS is found predominantly in men,” they add.
Goodson and colleagues also found that RA patients with fibromyalgia had significantly higher pooled Disease Activity Scores at 28 joints (DAS28) than those without, at a mean difference of 1.24 points. Similarly, patients with AS and fibromyalgia had 2.2-point higher overall Bath Ankylosing Spondylitis Disease Activity Index scores on average than patients with AS only, while evidence “was scarce” for patients with PsA.
These observations are likely to be clinically important because a difference of 1–2 points in disease activity scores “could be the difference between starting or stopping potentially harmful, and expensive, biologic drugs,” say the researchers.
They add that the authors of many studies included in the systematic review “attributed the observed influence of [fibromyalgia] to the subjective, self-reported components that comprise significant portions of disease scoring.” For example, the higher DAS28 scores observed among patients with RA and concomitant fibromyalgia were largely due to tender joint counts and visual analog scale global scores, rather than objective measures such as inflammatory markers.
“It is therefore important that these scores are interpreted in conjunction with knowledge of the presence of concomitant [fibromyalgia] to ensure optimal management and appropriate drug treatment,” concludes the team in Rheumatology.
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