A research team lead by David Walsh of the University of Nottingham concluded that longstanding rheumatoid arthritis (RA) patients can present with fibromyalgic symptoms and poorer mental health. The study, titled, “A cross sectional study of pain sensitivity, disease activity assessment, mental health and fibromyalgia status in rheumatoid arthritis,” was published online in Arthritis Research & Therapy, and enrolled a total of 50 patients from a rheumatology clinic at Sherwood Forest Hospitals NHS Foundation Trust. The patients were being treated with a regimen that included analgesics (69%), disease-modifying anti-rheumatic drugs (DMARDs), and/or glucocorticoids.

Pain is the primary reason RA patients seek rheumatologic care. Chronic joint inflammation leads to pain, but non-inflammatory processes may also contribute to increased pain sensitivity. In this study, over a 3-week period in 2013, patients (with RA, 76% female, mean age 60 years, 21% smokers) were administered different questionnaires to assess for pain.

To assess inflammation and correlated pain, researchers used the 28-point disease activity score (DAS28). To assess other types of pain, patients undertook the pressure pain detection thresholds (PPT) test and were given the McGill Pain Questionnaire. Widespread Pain Index (WPI) and Symptom Severity Scale (SSS) questionnaires allowed the classification of fibromyalgia (FM) according to the American College of Rheumatology criteria 2010. The participants’ mental health status was also evaluated by the researchers.

The study showed that, regardless of pharmacologic treatment, 48% of the participants met the criteria for FM, thus confirming previous studies that showed a higher prevalence of FM among RA patients. Additionally, higher scores for fibromyalgia criteria were associated with high pain sensitivity via PPT, and with poorer mental health scores.

This study reveals a subgroup of RA patients that is prone to enhanced pain due to FM. However, it is possible that an overlap between features of FM (fatigue and somatic symptoms) and RA can lead to over-classification. Finally, the high prevalence of FM in this particular group of patients may reflect easier volunteering among people with higher pain scores.

“Other pharmacological, psychological and physiotherapeutic approaches may be helpful for people with augmented pain processing associated with other forms of chronic musculoskeletal pain such as FM or low back pain, and should continue to be investigated in people with RA,” concluded the authors.