IMPAIRMENT-SPECIFIC DIMENSIONS WITHIN THE FUNCTIONAL INDEPENDENCE MEASURE

Objective: The analyses presented in this article were intended to see k more fine-grained impairment-specific dimensions beyond the motor an d cognitive dimensions of the Functional Independence Measure (FIMSM). Design: The study used factor analysis within 20 categories of impair ment to test the hypotheses that FIM items can be grouped according to functional areas of the body and that these gr item groupings differ depending on the patient's impairment. Patients: Data from 93,829 pati ents discharged in 1992 from 252 free-standing rehabilitation hospital s and units were obtained from the Uniform Data System for Medical Reh abilitation. Results: In 18 of 20 impairment categories, factor analys es of patients' admission FIM scores showed impairment-specific FIM di mensions. Four impairments had a 3-dimensional factor structure, and 1 4 had a 4-dimensional structure. The impairment-specific dimensions we re always nested within the motor-FIM subscale. Reliability coefficien ts for subscales based on these dimensions ranged from .74 to .97. The subscales appear to cluster FIM items by the area of body involved, n eurological level, or relative energy consumption. Conclusion: The FIM can be viewed as a multilayered multidimensional measure of human fun ction. The impairment-specific dimensions, at an intermediate layer, p rovide insight about the causal linkage between the impairment and res ultant patterns of disability. Impairment-specific subscales are relev ant to those clinical or research applications where the type of disab ility needs to be more closely related to impairment. (C) 1997 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.