Reliability and validity of the FIM for persons aged 80 years and above from a multilevel continuing care retirement...

Development of accurate functional assessment instruments will help clinicians evaluate treatment outcome and plan realistic rehabilitation goals for elderly patients. The reliability, validity, and appropriateness of the Functional Independence Measure (FIM) were examined for a population aged 80 years and more from a multilevel, continuing care retirement community.

Forty-nine residents (average age 89.7 years, range 80 to 104 years; 46 women), were randomly selected.

Subjects were grouped according to their residence in either an Independent community (18 subjects), Sheltered Care (16 subjects), or Skilled Nursing Facility (15 subjects).

Subjects were evaluated twice using the FIM. Motor and cognitive scores were converted into interval measures (logits) using Rasch Analysis with the BIGSTEPS statistical package. Parametric statistical procedures were utilized to further analyze data.

FIM motor and cognitive items formed 2 unidimensional and linear subscales. Hierarchical levels of FIM item difficulties were identified. Bladder management, bowel management, and grooming were misfitting motor items. Memory misfit for the cognitive subscale. High test-retest reliability for 45 repeated FIM assessments for the motor, (ICC = .9) and cognitive subscales (ICC = .8) was demonstrated. One way ANOVA for FIM ratings for the 3 groups demonstrated significant differences for both the motor subscale, F(2,46) = 34.71, p < .05, and the cognitive subscales, F(2,46) = 12.42, p < .05.

Construct validity of the FIM was demonstrated. High test-retest reliability was demonstrated. Environmental context and operational definitions influenced FIM ratings. Subjects' FIM ratings, abilities, and time to complete the locomotor walking item correlated with their current residence in increasingly dependent environments. These findings suggest that with certain caveats, the FIM may be useful as a functional assessment instrument for persons who are 80 or more years old.