Central sensitization symptoms are related to cortisol and cardiovascular activity in fibromyalgia: Further validation of the Central Sensitization Inventory

This study aimed to investigate the validity of the Central Sensitization Inventory (CSI) in patients with fibromyalgia (FM) via analysis of its predictive (associations with physiological variables and algometry measures) and discriminative (differentiating between patients with different chronic pain conditions) validity. In 43 women with FM and 36 healthy women, hair cortisol concentrations (HCC), cardiovascular variables when sitting, standing and lying down, pressure algometry and clinical variables were measured. For discriminative validity, another additional 39 women with FM and 33 women with rheumatoid arthritis (RA) also participated. In patients with FM, CSI scores correlated positively with HCC, total peripheral resistance and blood pressure (vascular factors), and inversely with inter-beat interval, stroke volume and cardiac output (cardiac factors), heart rate variability and baroreceptor reflex sensitivity (vagal cardiac variables), and pain threshold. Furthermore, CSI scores to predict the use of anxiolytics and opioid medication. Binary logistic regression analyses showed that CSI scores significantly discriminated among the three study groups, with progressively higher scores in FM, RA and healthy participants. This study provides support for the predictive and discriminative validity of CSI in patients with FM. Predictive validity in terms of physiological factors, such as cortisol and cardiovascular variables, could add utility to the CSI as a screener and treatment outcome measure. Furthermore, the CSI has good sensitivity and specificity in the discrimination of patients suffering from different conditions of chronic pain.