Is the strength of the baroreflex involvement during orthostatic position related to the impact of fibromyalgia on quality of life?

Background: Cardiovascular autonomic control has been widely studied in fibromyalgia syndrome (FMS). Nevertheless, there are many methodological difficulties in quantifying baroreflex sensitivity by traditional indices, especially regarding the issue of causality. Thus, a Granger causality approach has been recently proposed, revealing a reduced strength of baroreflex control during orthostatic stimulus in women with FMS. However, whether the reduced strength of the baroreflex control during orthostatic stimulus is related to the impact of fibromyalgia on quality of life is unknown. Objective: To evaluate the relationship between the strength of the baroreflex involvement during orthostatic position and the impact of fibromyalgia on quality of life. Methods: Twenty women with FMS took part in the study. The electrocardiogram, non-invasive finger blood pressure and respiratory activity were continuously recorded for all participants during 15 minutes in orthostatic position reached by active standing. A Granger causality approach was utilized to assess, through the calculation of the causality ratio, the strength of the causal relation from systolic arterial pressure (SAP) to heart period (HP) variability series (CR_SAP→HP). The more negative the CR_SAP→HP, the higher the strength of the causal link from SAP to HP. The impact of fibromyalgia on quality of life was quantified by the Fibromyalgia Impact Questionnaire (FIQ). Results: Pearson correlation analysis revealed a positive relationship between the CR_SAP→HP and the FIQ scores (r = 0.56, p < 0.01). Conclusions: The stronger the baroreflex involvement during orthostatic position in women with FMS, the lower the impact of fibromyalgia on quality of life.