Clinical Assessment of Autonomic Function in Fibromyalgia by the Refined and Abbreviated Composite Autonomic Symptom Score (COMPASS 31): A Case-Controlled Study

Background: It has been shown that autonomic dysfunction in fibromyalgia can be assessed by the Composite Autonomic Symptom Score (COMPASS) questionnaire. More recently, a refined and much abbreviated 31-item version of the questionnaire has been developed, the COMPASS 31. Objectives: First, to determine whether the COMPASS 31 can assess changes in autonomic function in fibromyalgia. Second, to assess whether the COMPASS 31 values in fibromyalgia patients are positively correlated with scores on the Revised Fibromyalgia Impact Questionnaire (FIQR). Methods: A cross-sectional, case-controlled study was carried out with 25 fibromyalgia patients and 26 healthy controls. Results: The two groups were matched for age, sex and ethnicity, but not for body mass index (BMI). The total mean (standard error) COMPASS 31 for the fibromyalgia patients, 37.2 (1.8), differentiated the patients from the controls (9.5 (1.4); p < 0.00000001). The scores were greater in the fibromyalgia patients across all COMPASS 31 autonomic domains, namely orthostatic intolerance (p < 0.00000001), and vasomotor (p < 0.0001), secretomotor (p < 0.000001), gastrointestinal (p < 0.000001), bladder (p < 0.00001) and pupillomotor functions (p < 0.00000001). The total COMPASS 31 values were positively correlated with FIQR scores (rs = 0.45, p < 0.05). General linear modelling of the COMPASS 31 scores showed that only group status (fibromyalgia or control) was significant (p = 3.4 × 10^-16), with age, sex and BMI being non-significant. Conclusion: This study confirms that non-pain autonomic dysfunction symptoms occur in fibromyalgia and can be assessed with the COMPASS 31.