Considerations on the psychometric properties and validity of the Spinal Cord Injury Secondary Conditons Scale

Abstract

Study design: Cross-sectional validation study. Objectives: Explore psychometric properties of Spinal Cord Injury Secondary Conditions Scale (SCI-SCS). Setting: Two Scandinavian rehabilitation centres. Methods: Included were 224 consecutive patients attending regular follow-up at least 1 year after a traumatic SCI. Mean age was 49.6 (SD 14.9) years. SCI-SCS floor and ceiling effect examined. Construct validity was investigated by confirmatory factor analysis and correlation analysis, and reliability by Cronbach’s alpha. Results: SCI-SCS showed no floor or ceiling effect. Two out of four earlier reported latent factors (“Genitourinary and bowel”, “Muscle structures and pain”) were confirmed. The global Cronbach’s alpha of SCI-SCS was 0.65 and 0.22–0.61 for the four latent factors. The SCI-SCS sum score showed low correlation to quality of life (QoL) measured by EQ5 VAS (rs = −0.47, p < 0.001). Likewise, the sum score correlations to QoL-general and QoL-physical health (International SCI QoL Basic Dataset) were low (rs = −0.36, p < 0.001 and rs = −0.37, p < 0.001, respectively). The scale item Muscle Spasms correlated moderately to ratings on Spasm Frequency (rs = 0.59, p < 0.001) and Spasm Intensity (rs = 0.56, p < 0.001) scales. Chronic Pain and Joint and Muscle Pain correlated to patient reported number of pain sites and level of pain (International SCI Pain Basic Dataset 1.0) (rs = 0.31 p < 0.001 and rs = 0.47, p < 0.001, respectively). Conclusion: SCI-SCS is a relevant instrument for giving clinicians and researchers an overview of the individual recent experiences with secondary conditions. However, the instrument could benefit from a clearer definition of the construct secondary conditions, a scale revision and a consideration of whether to add other experienced secondary conditions.