Function and disability in late life: comparison of the Late-Life Function and Disability Instrument to the Short-Form-36 and the London Handicap Scale

Purpose: We evaluated the Late-Life Function and Disability Instrument's (LLFDI) concurrent validity, comprehensiveness and precision by comparing it with the Short-Form-36 physical functioning (PF-10) and the London Handicap Scale (LHS). Methods: We administered the LLFDI, PF-10 and LHS to 75 community-dwelling adults ( 460 years of age). We used Pearson correlation coefficients to examine concurrent validity and Rasch analysis to compare the item hierarchies, content ranges and precision of the PF-10 and LLFDI function domains, and the LHS and the LLFDI disability domains. Results: LLFDI Function ( lower extremity scales) and PF-10 scores were highly correlated (r= 0.74-0.86, p>0.001); moderate correlations were found between the LHS and the LLFDI Disability limitation ( r= 0.66, p<0.0001) and Disability frequency ( r= 0.47, p<0.001) scores. The LLFDI had a wider range of content coverage, less ceiling effects and better relative precision across the spectrum of function and disability than the PF-10 and the LHS. The LHS had slightly more content range and precision in the lower end of the disability scale than the LLFDI. Conclusions: The LLFDI is a more comprehensive and precise instrument compared to the PF-10 and LHS for assessing function and disability in community-dwelling older adults.