Measuring quality of life of persons with spinal cord injury: Substantive and structural validation

The purpose of this study was to evaluate the substantive and structural va lidity of an existing measure of quality of life (QOL), the spinal cord inj ury (SCI) version of the Ferrans and Powers quality of life index (QLI). To evaluate substantive validity, 11 individuals with a SCI participated in ' think aloud' interviews to determine meaningfulness of the QLI items and to identify areas requiring modification. Free sort and ranking exercises of the items were used to evaluate the structural validity of the domains and scoring rubric. Content analysis of the interview comments resulted in the addition of two items and wording revision to three items. The free sort ex ercise revealed that the domains as perceived by the participants differed somewhat from those of the test developer. The contribution of the satisfac tion and importance sections proposed by the scoring model was not complete ly supported by the data from the ranking exercise. It is concluded that th e modified version of the QLI reflects the perspectives of persons with SCI spinal cord injury as represented by the participants of this study. The s tructural validity evaluation has implications for the use of domain subsco res and weighted vs. section scores. Further evaluation of the modified ver sion is necessary before widespread use with this patient population.