Validation of the Spinal Cord Injury Secondary Conditions Scale (SCI-SCS): Comparing self-reports with clinician ratings obtained during routine annual follow-up appointments in a specialized SCI center

CONTEXT: Secondary health conditions are highly prevalent among persons with spinal cord injury (SCI) and affect functioning, well-being, and survival. The SCI-Secondary Conditions Scale (SCI-SCS) is widely used to assess problems with secondary health conditions, yet its psychometric properties have not been evaluated, and validity of self-ratings against clinical assessments remains limited. OBJECTIVE: To evaluate the psychometric properties of the SCI-SCS and validate patient self-reports against ratings of their treating medical doctor. DESIGN: A monocentric study conducted at an SCI center in Switzerland. SETTING: = 300) prior to routine annual follow-up consultations, while the medical doctor independently rated the same scale. OUTCOME MEASURES: Psychometric properties of the SCI-SCS, including fit, dimensionality, and local item dependence (LID), were assessed with the Partial Credit Model (PCM). Interrater agreement was evaluated using root mean squared error, Wilcoxon signed-rank tests, differential item functioning, and correlations of Rasch-transformed scores. RESULTS: After accounting for LID, the SCI-SCS demonstrated good fit and unidimensionality. Nine out of 15 items showed good interrater agreement with small effect sizes. However, notable discrepancies were observed for sexual dysfunction, sleep problems, contractures, bladder dysfunction, bowel dysfunction, and circulatory problems. Except for bladder dysfunction, patients tended to report higher problem severity than clinicians. CONCLUSION: The SCI-SCS is a psychometrically sound tool for assessing secondary conditions in people with SCI; however, self-reports may overestimate severity compared to physician ratings and should be interpreted with caution given differences between clinical judgement and patients' lived experience.