Measuring quality of life of persons with spinal cord injury: external and structural validity

Study design: Measurement evaluation of the external and structural components of validity. Objectives: To examine the relationships between quality of life (QOL) as measured by the spinal cord injury (SCI) version of the Ferrans and Powers Quality of Life Index (QLI) and other constructs represented within the model of disablement; and to examine the domains and scoring model of the QLI by exploring item and overall score/section score relationships. Setting: Community, Alberta, Canada. Methods: A convenience sample of 98 individuals with SCI living in the community completed the QLI and measures representing the model of disablement including the ASIA motor index, Functional Independence Measure, Reintegration to Normal Living index, Rosenberg's Self-Esteem Scale and Rotter's Internal-External Locus of Control scale. Results: Four of the five a priori hypotheses were supported. Locus of control was not significantly related to QOL as expected. Factor analysis resulted in a five-factor structure that differed from the four-domain model of the original QLI. Scoring relationships indicated that both the satisfaction and importance ratings contribute to the overall score, although not equally. Conclusion: There is support for the external component of validity although further examination regarding locus of control for persons with SCI is warranted. The structural component of validity requires further investigation to elucidate the domains of the SCI version of the QLI and the contribution of the importance scores.