High test-retest reliability was found for the Function component , while results for the Disability component were more variable .
Conclusions There is extensive evidence to support the construct validity and sensitivity to change of the LLFDI among various clinical population s of community-dwelling older adults .
Background The choice of measure for use as a primary outcome in geriatric research is contingent upon the construct of interest and evidence for its psychometric properties .
The Late-Life Function and Disability Instrument ( LLFDI ) has been widely used to assess functional limitations and disability in studies with older adults .
The primary aim of this systematic review was to evaluate the current available evidence for the psychometric properties of the LLFDI .
Creating a computer adaptive test version of the late-life function and disability instrument.
BACKGROUND This study applied item response theory ( IRT ) and computer adaptive testing ( CAT ) method ologies to develop a prototype function and disability assessment instrument for use in aging research . Herein , we report on the development of the CAT version of the Late-Life Function and Disability Instrument ( Late-Life FDI ) and evaluate its psychometric properties . METHODS We used confirmatory factor analysis , IRT methods , validation , and computer simulation analyses of data collected from 671 older adults residing in residential care facilities . We compared accuracy , precision , and sensitivity to change of scores from CAT versions of two Late-Life FDI scales with scores from the fixed-form instrument . Score estimates from the prototype CAT versus the original instrument were compared in a sample of 40 older adults . RESULTS Distinct function and disability domains were identified within the Late-Life FDI item bank and used to construct two prototype CAT scales . Using retrospective data , scores from computer simulations of the prototype CAT scales were highly correlated with scores from the original instrument . The results of computer simulation , accuracy , precision , and sensitivity to change of the CATs closely approximated those of the fixed-form scales , especially for the 10- or 15-item CAT versions . In the prospect i ve study , each CAT was administered in <3 minutes and  CAT scores were highly correlated with scores generated from the original instrument . CONCLUSIONS CAT scores of the Late-Life FDI were highly comparable to those obtained from the full-length instrument with a small loss in accuracy , precision , and sensitivity to change
High test-retest reliability was found for the Function component , while results for the Disability component were more variable .
Conclusions There is extensive evidence to support the construct validity and sensitivity to change of the LLFDI among various clinical population s of community-dwelling older adults .
Background The choice of measure for use as a primary outcome in geriatric research is contingent upon the construct of interest and evidence for its psychometric properties .
The Late-Life Function and Disability Instrument ( LLFDI ) has been widely used to assess functional limitations and disability in studies with older adults .
The primary aim of this systematic review was to evaluate the current available evidence for the psychometric properties of the LLFDI .