This study aimed to determine the optimal cutoff score of the 9-item short version of the CSI, the CSI-9, by comparing patients with central sensitivity syndrome (CSS) not only to healthy volunteers as with the original version, but also to patients with musculoskeletal (MSK) disorders.
All participants filled out the CSI, EuroQol 5-dimension, Brief Pain Inventory, and Pain Catastrophizing Scale questionnaires. To identify a clinically relevant cutoff score, receiver operating characteristic analyses were conducted. The area under the curve was used to examine the ability of the CSI-9 to distinguish patients with fibromyalgia (FM) from patients with MSK disorders and healthy individuals.
Twenty-six participants with FM, 30 patients with MSK disorders, and 28 healthy individuals were included. We determined 2 cutoff scores: 20 for distinguishing patients with FM from patients with MSK disorders and 17 for distinguishing patients with FM from healthy individuals. These cutoff scores had good sensitivity (patients with MSK disorders, 92.3%; healthy individuals, 96.2%) and specificity (patients with MSK disorders, 93.3%; healthy individuals, 100%). In addition, the patients who scored above the cutoff of 20 points exhibited worse clinical symptoms (higher pain intensity, higher pain interference, higher Pain Catastrophizing Scale scores, and lower EuroQol 5-dimension scores) than those who scored below it. Furthermore, a significantly higher number of subjects who scored more than 20 on the CSI-9 had a history of 2 or more diagnoses of CSS.
The optimal CSI-9 cutoff score of 20 is beneficial to clinicians in the evaluation of central sensitization-related symptoms. The cutoff score helps to identify patients who need additional treatments, such as pain neuroscience education and cognitive behavioral therapy.