A cross-sectional study of pain sensitivity, disease-activity assessment, mental health, and fibromyalgia status in rheumatoid arthritis

Nalinie Joharatnam, Daniel F McWilliams, Deborah Wilson, Maggie Wheeler, Ira Pande, David A Walsh

IntroductionPain remains the most important problem for people with rheumatoid arthritis (RA). Active inflammatory disease contributes to pain, but pain due to non-inflammatory mechanisms can confound the assessment of disease activity. We hypothesise that augmented pain processing, fibromyalgic features, poorer mental health and patient-reported 28 joint disease activity score (DAS28) components are associated in RA.MethodsA total of 50 people with stable, longstanding RA recruited from a rheumatology outpatient clinic were assessed for pain pressure thresholds (PPT) at three separate sites (knee, tibia and sternum), DAS28, fibromyalgia and mental health status. Multivariable analysis was performed to assess the association between PPT and DAS28 components, DAS28-P (the proportion of DAS28 derived from the patient-reported components of visual analogue score and tender joint count) or fibromyalgia status.ResultsMore sensitive PPTs at sites over or distant from joints were each associated with greater reported pain, higher patient-reported DAS28 components and poorer mental health. A high proportion of participants (48%) satisfied classification criteria for fibromyalgia, and fibromyalgia classification or characteristics were each associated with more sensitive PPTs, higher patient-reported DAS28 components and poorer mental health.ConclusionsWidespread sensitivity to pressure-induced pain, a high prevalence of fibromyalgic features, higher patient-reported DAS28 components and poorer mental health are all linked in established RA. The increased sensitivity at non-joint sites (sternum and anterior tibia) as well as over joints indicates that central mechanisms may contribute to pain sensitivity in RA. The contribution of patient reported components to high DAS28 should inform decisions on disease modifying or pain management approaches in the treatment of RA when inflammation may be well-controlled.