Patients With Fibromyalgia Have Significant Autonomic Symptoms But Modest Autonomic Dysfunction

Background: Research suggests that disordered autonomic function may be one contributor to deconditioning reported in fibromyalgia; however, no study to date has assessed these variables simultaneously with comprehensive measures. Objective: To characterize physical fitness and autonomic function with the use of clinically validated measures and subjective questionnaires between patients with fibromyalgia and healthy controls. Design: Cross-sectional, observational, controlled study. Setting: Community sample of patients with fibromyalgia and healthy controls. Participants: Thirty patients with fibromyalgia and 30 pain and fatigue-free controls. Methods: Participants completed a battery of self-report questionnaires and physiological measures, including clinically validated measures of physical fitness and autonomic function. Main Outcome Measurements: Six-Minute Walk Test total distance, maximal oxygen consumption as assessed by cardiopulmonary exercise testing, total steps using activity monitor, Composite Autonomic Scoring Scale as assessed by Autonomic Reflex Screen, total metabolic equivalents per week using the International Physical Activity Questionnaire, and self-reported autonomic symptoms via the 31-item Composite Autonomic Symptom Score questionnaire. Results: Autonomic function, as assessed by self-report, was significantly different between patients and controls (P < .0001); in contrast, the only difference between patients and controls on the Autonomic Reflex Screen was in the adrenergic domain (P = .022), and these abnormalities were mild. Self-reported physical activity was not significantly different between patients and controls (P = .99), but levels of moderate and vigorous physical activity as measured by actigraphy were significantly lower in patients (P = .012 and P = .047, respectively). Exercise capacity (6-Minute Walk) was poorer in patients (P = .0006), but there was no significant difference in maximal volume of oxygen consumption (P = .07). Conclusions: Patients with fibromyalgia report more severe symptoms across all domains, including physical activity and autonomic symptoms, compared with controls, but the objective assessments only showed modest differences. Our results suggest that patients with widespread subjective impairment of function have only modest objective measures of autonomic dysfunction. We recommend that the primary treatment goal should be focused on restoration of function, which may also ameliorate symptoms.