Symptoms of Fibromyalgia According to the 2016 Revised Fibromyalgia Criteria in Chronic Pain Patients Referred to Multidisciplinary Pain Rehabilitation: Influence on Clinical and Experimental Pain Sensitivity

Fibromyalgia (FM) is a condition with chronic widespread pain and signs of generalized pain hypersensitivity. FM has previously been classified according to the American College of Rheumatology-1990 criteria, where the presence of hypersensitivity is estimated by a tender point examination. Because of the limitations of these classification criteria, new diagnostic criteria have been proposed, abandoning this examination. This cross-sectional study investigated the prevalence of FM according to the revised 2016 FM criteria in a large cohort of chronic pain patients. Pain drawings, the FM Symptom Severity Scale, and questionnaires assessing manifestations of pain, pain related disability, and psychological distress were collected from 1,343 patients with chronic nonmalignant pain referred to a multidisciplinary pain clinic. In addition, assessments of mechanical and thermal pain sensitivity were performed in 496 of the patients. Patients fulfilling the FM criteria (n = 498, 37%) reported significantly higher levels of pain, pain-related disability, psychological distress, and sensitivity to mechanical and heat stimuli (P<.05). Moreover, the proportion using opioids were significantly higher compared with patients not fulfilling the criteria (P=.015). Significant associations were found between heat and mechanical pain sensitivity (P<.001) indicating that patients who showed higher pain sensitivity to mechanical stimulation also showed higher pain sensitivity to thermal stimulation. Perspective: More than one-third of patients were classified as FM, and patients classified showed increased clinical and experimental pain profiles. Because no data were collected on whether the included patients had a clinical FM diagnosis, future studies validating the American College of Rheumatology-2016 criteria in a cohort of patients with chronic nonmalignant pain are warranted. (C) 2018 by the American Pain Society