Concomitant Fibromyalgia in Patients With Other Rheumatic Diseases: Pain Level and Treatment Response

Introduction: Fibromyalgia commonly coexists with rheumatic diseases and may complicate disease assessment and management. This study evaluated whether patients with rheumatic diseases and concomitant fibromyalgia differed in pain severity and patient-perceived treatment response compared with those without fibromyalgia. Methods: Four patient groups were evaluated in a historical, cross-sectional study: (1) fibromyalgia alone, diagnosed using the 2016 American College of Rheumatology criteria; (2) another rheumatic disease and concomitant fibromyalgia, requiring a fibromyalgia Polysymptomatic Distress Scale (PDS) score of >11 points; (3) another rheumatic disease and a PDS score of 10 or 11 indicating “borderline” fibromyalgia; (4) a control group consisting of patients with nonfibromyalgia rheumatic disease and a PDS score <10. Pain level (0=no pain, 10=worst pain possible) and treatment response (0=no response, 10=positive response) were assessed with visual analog scales. Results: Among 503 patients, 108 were diagnosed with fibromyalgia alone; 83 with concomitant FMS; 39 with borderline FMS; and 273 with nonfibromyalgia rheumatic disease. The worst pain was reported by patients with concomitant fibromyalgia (mean, 6.7), followed by those with fibromyalgia alone (6.3) and borderline concomitant fibromyalgia (6.2). Nonfibromyalgia patients reported a pain level of 4. Patients with fibromyalgia alone, concomitant fibromyalgia, and borderline concomitant fibromyalgia reported worse response to treatment (6.4, 7.1, and 7.8) than nonfibromyalgia patients (8.3). Conclusion: These findings underscore the pain burden and difficulty in treating patients with inflammatory rheumatic diseases and concomitant fibromyalgia. Recognizing fibromyalgia in patients with other rheumatic diseases is important to tailor more effective pain management strategies, improve treatment outcomes, and distinguish symptoms related to fibromyalgia from those of the underlying rheumatic disease.