@article{ProdingerBallertBrachetal.2016, author = {Prodinger, Birgit and Ballert, C. S. and Brach, M. and Brinkhof, M. W. G. and Cieza, A. and Hug, K. and Jordan, X. and Post, M. W. M. and Scheel-Sailer, A. and Schubert, M. and Tennant, A. and Stucki, G.}, title = {Toward standardized reporting for a cohort study on functioning: The Swiss Spinal Cord Injury Cohort Study}, series = {Journal of Rehabilitation Medicine}, volume = {48}, journal = {Journal of Rehabilitation Medicine}, number = {2}, pages = {189 -- 196}, year = {2016}, abstract = {Objective: Functioning is an important outcome to measure in cohort studies. Clear and operational outcomes are needed to judge the quality of a cohort study. This paper outlines guiding principles for reporting functioning in cohort studies and addresses some outstanding issues. Design: Principles of how to standardize reporting of data from a cohort study on functioning, by deriving scores that are most useful for further statistical analysis and reporting, are outlined. The Swiss Spinal Cord Injury Cohort Study Community Survey serves as a case in point to provide a practical application of these principles. Methods and Results: Development of reporting scores must be conceptually coherent and metrically sound. The International Classification of Functioning, Disability and Health (ICF) can serve as the frame of reference for this, with its categories serving as reference units for reporting. To derive a score for further statistical analysis and reporting, items measuring a single latent trait must be invariant across groups. The Rasch measurement model is well suited to test these assumptions. Conclusion: Our approach is a valuable guide for researchers and clinicians, as it fosters comparability of data, strengthens the comprehensiveness of scope, and provides invariant, interval-scaled data for further statistical analyses of functioning.}, language = {en} } @article{ProdingerBallertBrinkofetal.2016, author = {Prodinger, Birgit and Ballert, C.S. and Brinkof, M. W. G. and Tennant, A. and Post, M. W. M.}, title = {Metric properties of the Spinal Cord Independence Measure - Self Report in a community survey}, series = {Journal of Rehabilitation Medicine}, volume = {48}, journal = {Journal of Rehabilitation Medicine}, number = {2}, pages = {149 -- 164}, year = {2016}, abstract = {Objective: The Spinal Cord Independence Measure - Self Report (SCIM-SR) is a self-report instrument for assessing functional independence of persons with spinal cord injury. This study examined the internal construct validity and reliability of the SCIM-SR, when administered in a community survey, using the Rasch measurement model. Methods: Rasch analysis of data from 1,549 individuals with spinal cord injury who completed the SCIM-SR. Results: In the initial analysis no fit to the Rasch model was achieved. Items were grouped into testlets to accommodate the substantial local dependency. Due to the differential item functioning for lesion level and degree, spinal cord injury-specific sub-group analyses were conducted. Fit to the Rasch model was then achieved for individuals with tetraplegia and complete paraplegia, but not for those with incomplete paraplegia. Comparability of ability estimates across sub-groups was attained by anchoring all sub-groups on a testlet. Conclusion: The SCIM-SR violates certain assumptions of the Rasch measurement model, as shown by the local dependency and differential item functioning. However, an intermediate solution to achieve fit in 3 out of 4 spinal cord injury sub-groups was found. For the time being, therefore, it advisable to use this approach to compute Rasch-transformed SCIM-SR scores.}, language = {en} }