Longitudinal invariance and construct validity of the abbreviated late-life function and disability instrument in healthy older adults

Szabo AN, Mullen SP, White SM, Wojcicki TR, Mailey EL, Gothe N, Olson EA, Fanning J, Kramer AF, McAuley E. Longitudinal invariance and construct validity of the abbreviated Late-Life Function and Disability Instrument in healthy older adults.

Objective

To cross-validate the psychometric properties of the abbreviated Late-Life Function and Disability Instrument (LL-FDI), a measure of perceived functional limitations and disability.

Design

Baseline and 12-month follow-up assessments conducted across the course of a 12-month exercise program.

Setting

University research community.

Participants

Older healthy adults (N=179; mean ± SD age, 66.43±5.67y) at baseline; 145 were retained at follow-up.

Interventions

Not applicable.

Main Outcome Measures

LL-FDI and functional performance measures.

Results

Factor analyses confirmed the factor structure of the abbreviated LL-FDI, and all subscales met minimal criteria for temporal invariance. Significant correlations also were found between functional limitations subscales and an array of physical function performance measures, supporting the scale's construct validity.

Conclusions

The abbreviated LL-FDI with some modifications appears to be temporally invariant in community-dwelling older adults. Additionally, moderate relationships between functional limitations and functional performance provide further support for these being conceptually distinct constructs.