Researchers use various measures to assess health status, impairment, functional limitations, and disability among people with multiple sclerosis (MS). Conceptual and empirical associations among measures are not always clear, however. The purpose of this study was to examine the relationships among measures of impairment, disability, functional status, and health-related outcomes in a sample of 443 individuals with MS. A secondary purpose was to compare the self-reported health status of this sample with that of a population-based sample of individuals with and without disabilities. Although both the MS sample and a population-based sample of individuals with activity limitations indicated poorer health than did their nondisabled counterparts, the MS sample reported more days in the preceding month when their physical and mental health were not good and more days when poor health kept them from usual activities than the population-based sample of individuals with disabilities. Most measures were moderately intercorrelated, but the pattern suggests that issues such as the time frame specified may affect the relationships. Researchers should carefully consider operational as well as conceptual definitions, length of proposed measures, and appropriate time frame, in addition to the more traditional criteria of reliability and validity, when selecting study measures.
From the School of Nursing, The University of Texas at Austin, Austin, TX, USA.