| Central Sensitivity Syndrome (CSS) includes a group of related conditions that share a common pathophysiological mechanism called central sensitization (e.g., fibromyalgia, irritable bowel syndrome, tension headache/migraine, etc.). Individuals with these conditions display increased pain sensitivity in response to painful stimuli, pain in response to normally non-painful stimuli, and expansion of the receptive field. Depression and anxiety frequently occur among individuals with CSS, as well as disturbed sleep, somatic symptoms and emotional distress. The Central Sensitization Inventory (CSI) is a newly developed self-report measure to assess the full array of 25 somatic and emotional symptoms associated with CSS. The present study sought to examine the concurrent validity of the CSI, and the predictive ability of the pre-determined cut-off point of 40, and the proposed severity cutoffs of 30, 40, 50, and 60 on the CSI associated with program completion and/or one-year socioeconomic outcomes. A total of 681 patients with a Chronic Disabling Occupational Musculoskeletal Disorder (CDOMD) were collected from a regional functional restoration program (FRP). A series of univariate and multivariate regression analyses were utilized to identify key factors contributing to the total CSI scores at FRP admission. Results revealed that CDOMD patients with high CSI scores were likely; to be diagnosed with post-injury Major Depressive Disorder (MDD) and Generalized Anxiety Disorder (GAD); to have spinal disorders (opposed to extremity disorders); to report previous history of CSS; and to have an abuse experience history. The CSI was moderately associated with other psychosocial instruments measuring components involving CSS, such as somatization-related symptoms, depression, and sleep disturbance. For FRP completion rate, the high CSI score predicted a lower rate of program completion. After completing the FRP, the average CSI scores were significantly reduced. The CSI score at FRP discharge was a significant independent predictor of work retention one-year post FRP. The five CSI ordinal severity categories, rather than a single CSI cutoff, were successfully associated with substantially lower rate of work retention one-year post FRP and high frequency of the treatment seeking behaviors. The results support that the CSI is a clinically valid and useful instrument, which can be used to assess CSS-relevant multiple symptoms, and to monitor treatment outcomes. The established five CSI severity levels provide a guideline for clinicians in interpreting and using CSI scores in clinical trials. |
