Central Sensitization Inventory is a useless instrument for detection of the impairment of the conditioned pain modulation in patients with chronic musculoskeletal pain

OBJECTIVE: The current study aimed to evaluate the concurrent validity and the diagnostic accuracy of the Central Sensitization Inventory (CSI) in detecting the impairment of the pain modulation in patients with chronic musculoskeletal pain. METHODS: A cross-sectional study was conducted in 267 patients with chronic musculoskeletal pain enrolled consecutively in an outpatient department. The CSI (index method) were compared with the cold pressor test, which was the psychophysical test used to assess the conditioned pain modulation (CPM), (reference standard). Spearman's correlations assessed the concurrent validity, and measurements of the diagnostic accuracy were performed. RESULTS: Ninety-three (34.8%) patients had CSI scores≥40. No significant correlation was found between CSI findings and the results of the CPT (dorsal forearm site or tibialis anterior site) was found. The cutoff point of 40 of the CSI showed values of sensitivity (35.1%, 95% CI: 22.6, 49.3) and specificity (65.2%, 95% CI: 58.4, 71.6) below 70%, and an accuracy of 59.1 (95% CI: 53.0, 65.1) when compared to the CPT to detect deficit. The ROC curve analysis yielded an area under the curve of 0.54 (95% CI: 0.45, 0.63, P>0.05). CONCLUSIONS: The CSI is a useless instrument to detect the deficit in the CPM in patients with chronic musculoskeletal pain due to the absence of correlation with the psychophysical test result and the insufficient measurements of diagnostic accuracy.