Assessing Validity of the Original and Rasch Versions of the Central Sensitization Inventory with Psychophysical Tests in People with Knee Osteoarthritis

OBJECTIVE: To determine the extent of agreement between the original Central Sensitization Inventory (CSI) and the Rasch-calibrated version (RC-CSI) and to explore the association of both versions with psychophysical tests and their respective sensitivity and specificity. METHODS: Patients with knee osteoarthritis who were enrolled in a multicenter cohort study in Montreal, Canada, completed the original CSI, the RC-CSI, and psychophysical tests (i.e., pressure pain thresholds, temporal summation, conditioned pain modulation) according to standardized protocols. Bland-Altman analyses assessed the agreement between the original CSI and the RC-CSI; Spearman correlations and chi-squared analyses evaluated the association between the two CSI scores and the psychophysical tests. A CSI cut point of 40 and an RC-CSI cut point of 31.37 were used. Receiver operating characteristic curves and the resulting sensitivity and specificity with psychophysical tests were also analyzed. RESULTS: Two hundred ninety-three participants were included (58.7% female, mean age of 63.6 years, and body mass index 31.9 kg/m2). The original CSI and RC-CSI mean difference, 3.3/8.2, t(292) = 8.84 (P < 0.001), was significantly different and indicated a small bias. Small but significant inverse correlations were found for the original CSI and RC-CSI scores with pressure pain thresholds at the forearm and patella, with variance explained ranging from 0.01 to 0.12. The largest area under the curve suggested cut points of 23 (CSI) and 25 (RC-CSI) with 80.9% sensitivity and 38.5% specificity. CONCLUSIONS: Because of poor variance explained with psychophysical tests and high false positive rates, our results indicate that there is little clinical value of using either version of the CSI in people with knee osteoarthritis.