Reliability and validity of the French-Canadian Late Life Function and Disability Instrument in community-living wheelchair-users

Objective: To examine the test-retest reliability, standard error of measurement, minimal detectable change, construct validity, and ceiling and floor effects in the French-Canadian Late Life Function and Disability Instrument (LLFDI-F). Method: The LLFDI-F is a measure of activity (i.e. physical functioning of upper and lower extremities), and participation (i.e. frequency of and limitations with). The measure was administered over the telephone to a sample of community-living wheelchair-users, who were 50 years of age and older, in this 10-day retest methodological study. The sample (n = 40) was mostly male (70%), had a mean age of 62.2 years, and mean experience with using a wheelchair of 20.2 years. Sixty-five percent used a manual wheelchair. Results: The test-retest intraclass correlation coefficients (ICC2,1) for the participation component ranged from 0.68 to 0.90 and from 0.74 to 0.97 for the activity component. Minimal detectable changes ranged from 7.18 to 22.56 in the participation component and from 4.71 to 16.19 in the activity component. Mann-Whitney U-tests revealed significant differences between manual and power wheelchair-users in the personal and instrumental role domains, and all areas in the activity component. Conclusion: There is support for the test-retest reliability and construct validity of the LLFDI-F in community-living wheelchair-users, 50 years of age and older. However, because the majority of items in the lower-extremity domains of the activity component do not account for assistive device use, they are not recommended for use with individuals who have little or no use of their lower-extremities.