A pilot study to modify the SF-36V physical functioning scale for use with veterans with spinal cord injury
Stephen L Luther1, Jeffrey Kromrey, Gail Powell-Cope
1VISN 8 Patient Safety Research Center, James A. Haley Veterans Hospital, Tampa, FL 33612, USA. steve.luther@med.va.gocv
Objective:
To 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.
Design:
A 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.
Setting:
A VHA SCI center.
Participants:
The sample consisted of valid responses from 359 veterans with traumatic SCI who were seen at a VHA SCI center during the prior year (2002).
Interventions:
Not applicable.
Main Outcome Measure:
Physical functioning in people with SCI.
Results:
Exploratory 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.
Conclusions:
Although 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.
