A Pilot Study to Modify the SF-36V Physical Functioning Scale for Use With Veterans With Spinal Cord Injury

Luther SL, Kromrey J, Powell-Cope G, Rosenberg D, Nelson A, Ahmed S, Quigley P. A pilot study to modify the SF-36V physical functioning scale for use with veterans with spinal cord injury.ObjectiveTo develop a valid and reliable spinal cord injury (SCI) specific physical functioning (PF) scale for the Veterans Health Administration (VHA) version of the 36-Item Short-Form Health Survey.DesignA mixed qualitative and quantitative research design was used. In phase 1, a pool of SCI-specific PF items was generated based on focus groups with patients and health care providers. In phase 2, the psychometric properties of the SCI-specific PF scale were established.SettingA VHA SCI center.ParticipantsThe sample consisted of valid responses from 359 veterans with traumatic SCI who were seen at a VHA SCI center during the prior year (2002).InterventionsNot applicable.Main Outcome MeasurePhysical functioning in people with SCI.ResultsExploratory factor analysis was conducted separately on respondents with lower neurologic-level injuries (paraplegia, 53% [n=190]) and those with higher neurologic-level injuries (tetraplegia, 45% [n=163]) and identified 9 items loading on 1 factor in both groups. These 9 items were included in separate item response theory (IRT) model analyses for each subgroup. Based on the IRT analysis, 1 item was eliminated, resulting in an 8-item, SCI-specific PF scale.ConclusionsAlthough several of the items in the SCI-specific PF scale showed floor effects, particularly in people with tetraplegia, we found excellent reliability and strong support of convergent and divergent validity of the scale.