Equating activities of daily living outcome measures: the Functional Independence Measure and the Korean version of Modified Barthel Index.

PURPOSE: To create a crosswalk between the Functional Independence Measure (FIM) motor items and the Korean version of the Modified Barthel Index (K-MBI).

METHOD: Korean community-dwelling adult patients (n = 276) completed the FIM and K-MBI on the same day in outpatient rehabilitation hospitals. We used a single group design with the Rasch common person equating and conducted a factor analysis of the co-calibrated item pool using the two measures. Rasch analysis was used to investigate the psychometrics of the equated test items in the identified factor structure(s). The correlation between FIM raw scores and converted K-MBI scores was examined.

RESULTS: Three measurement constructs were identified: self-care, mobility, involuntary movement. The equated test items in the three constructs demonstrated good person separation reliability (r = 0.94-0.96) and good internal consistency (Cronbach's alpha =0.93-0.97). The three crosswalks between the FIM raw scores and converted K-MBI scores demonstrated good correlations (r = 0.91-0.93, all p < 0.0001).

CONCLUSIONS: The Rasch equating method successfully created three crosswalks between the FIM motor items and K-MBI, with the equated test items demonstrating good psychometrics. The crosswalks would address the incomparable scoring systems between the FIM motor items and K-MBI. Implications for Rehabilitation The three crosswalk tables (scoring tables) would allow clinicians to compare or translate a patient's motor scores between the FIM and K-MBI. The crosswalk tables would allow health-care administrators to track patients' functional status across various rehabilitation facilities that exclusively use the FIM or K-MBI.