Walking index for spinal cord injury (WISCI): an international multicenter validity and reliability study

Study design: Construction of an international walking scale by a modified Delphi technique. Objective: The purpose of the study was to develop a more precise walking scale for use in clinical trials of subjects with spinal cord injury (SCI) and to determine its validity and reliability. Setting: Eight SCI centers in Australia, Brazil, Canada (2), Korea, Italy, the UK and the US. Methods: Original items were constructed by experts at two SCI centers (Italy and the US) and blindly ranked in an hierarchical order (pilot data). These items were compared to the Functional Independence Measure (FIM) for concurrent validity. Subsequent independent blind rank ordering of items was completed at all eight centers (24 individuals and eight teams). Final consensus on rank ordering was reached during an international meeting (face validation). A videotape comprised of 40 clips of patients walking was forwarded to :all eight centers and inter-rater reliability data collected. Results: Kendall coefficient of concordance for the pilot data was significant (W=0.843, P<0.001) indicating agreement among the experts in rank ordering of Original items. FIM comparison (Spearmans rank correlation coefficient=0.765, P<0.001) showed a theoretical relationship, however a practical difference in what is measured by each scale. Kendall coefficient of concordance for the international blind hierarchical ranking showed significance (W = 0.860, P<0.001) indicating agreement in rank ordering across all eight centers. Group consensus meeting resulted in a 19 item hierarchical rank ordered 'Walking Index for Spinal Cord Injury (WISCI)'. Inter-rater reliability scoring of the 40 video clips showed 100% agreement. Conclusions: This is the first time a walking scale for SCI of this complexity has been developed and judged by an international group of experts. The WISCI showed good validity and reliability, but needs to be assessed in clinical settings for responsiveness.