Predicting patient scores between the functional independence measure and the minimum data set: development and performance of a FIM-MDS "crosswalk".[erratum appears in Arch Phys Med Rehabil 1998 Feb;79(2):231]

OBJECTIVE: The functional status of rehabilitation patients is often measured using the Functional Independence Measure (FIM) in acute rehabilitation settings or the Minimum Data Set (MDS) in nursing homes. Because the relationship between the two instruments is unknown, preventing comparison of rehabilitation patients in different types of settings, a translation formula ("crosswalk") between items and subscales from the FIM and the MDS was developed and tested. DESIGN AND OUTCOME MEASURES: Using definitions recommended by an expert panel, MDS items were chosen and rescaled (termed "Pseudo-FIM(E)" items) to correspond to FIM items. The empiric relationships between Pseudo-FIM(E) and FIM scores were then measured using paired FIM-MDS assessments. SETTING AND PATIENTS: 173 rehabilitation patients admitted to six nursing homes. RESULTS: Pseudo-FIM(E) items could be defined for 12 of the 18 FIM items (8 motor and 4 cognitive items). Mean FIM and Pseudo-FIM(E) scores were not significantly different (p > .30) for 5 of the 12 items. Mean scores for the remaining 7 items and for motor and cognitive subscales were similar but statistically significantly different (p < .05). Intraclass correlation coefficients between the FIM and Pseudo-FIM(E) motor and cognitive subscales were both .81. CONCLUSIONS: FIM and MDS items can be used to predict item and subscale scores between the two instruments with reasonable accuracy. This capability will enhance efforts to compare case-mix between acute rehabilitation and nursing home rehabilitation patients, thus making feasible comparisons of the effectiveness (degree of improvement among similar patients) and efficiency (cost of care to obtain a given degree of improvement) of rehabilitation care in different types of settings.