Functional Independence Measure

Developed in 1987, in part as a response to criticism of the Barthel Index (BI), the Functional Independence Measure (FIM) was intended to address issues of sensitivity and comprehensiveness as well as provide a uniform measurement system for disability for use in the medical remuneration system in the United States (McDowell & Newell 1996). Rather than independence or dependence, the FIM assesses physical and cognitive disability in terms of burden of care, meaning the FIM score is intended to represent the burden of caring for that individual.

The FIM is a composite measure consisting of 18 items assessing six areas of function (i.e. self-care, sphincter control, mobility, locomotion, communication and social cognition). These fall into two basic domains: 1) physical (13 items) and 2) cognitive (5 items). The 13 physical items are based on those found on the Barthel Index (BI), while the cognitive items are intended to assess social interaction, problem-solving and memory. The physical items are collectively referred to as the motor-FIM while the remaining 5 items are referred to as the cognitive-FIM. The scale has not been found to fit with the Rasch model with MS patients (Mills et al. 2009).

Each item is scored on a 7-point Likert scale indicative of the amount of assistance required to perform each item (1=total assistance, 7=total independence). A simple summed score of 18-126 is obtained where 18 represents complete dependence/total assistance and 126 represents complete independence. Subscale scores for the physical and cognitive domains may also be used and may yield more useful information than combining them into a single FIM score (Linacre et al. 1994).

Administration of the FIM requires training and certification. The most common approach to administration is direct observation and the FIM takes approximately 30 minutes to administer and score. The developers of the FIM further recommend that the rating be derived by consensus opinion of a multi-disciplinary team after a period of observation.

Table: Characteristics of Functional Independence Measure

Advantages. The FIM is a widely used, well-accepted, generic measure of burden of care used in inpatient rehabilitation settings. In clinical assessment, the greater number of items and wider choice of responses per item may yield more detailed information on an individual basis than assessments, such as the BI, with fewer items and response options (Hobart et al. 2001).

Limitations. The reliability of the FIM is dependent upon the individual conducting the assessment. Training and education in administration of the test is a pre-requisite for good levels of inter-rater reliability (Cavanagh et al. 2000) (stroke). Length of time and amount of training required to arrive at a consensus score, as recommended by the developers of the FIM, may have significant implications for the practical application of the FIM in clinical practice.

The use of a single summed raw score may be misleading as it gives the appearance of a continuous scale. Steps between scores, however, are not equal in terms of level of difficulty and cannot provide more than ordinal level information (Linacre et al. 1994). Kidd et al. (1995) (varying etiologies) suggested that one may use the summed scores as though on an interval level scale while the individual items remain ordinal.

Kidd et al. (1995) suggest that the inclusion of items related to communication and cognition as well as the ranking of 7 levels of severity for each item make the FIM more sensitive and inclusive. However, the contribution of the cognitive subscale to the scale as a whole is questionable. It has been shown to have less reliability and responsiveness than either the motor FIM or the total FIM (Hobart et al. 2001; Ottenbacher et al. 1996; van der Putten et al. 1999).

In an evaluation of responsiveness, FIM, motor FIM and the BI were all found to have similar effect sizes. The total-FIM was reported to exhibit no ceiling effect, 0% as compared to the BI’s 7% (van der Putten et al. 1999). This would suggest that the FIM might have no real advantage in terms of responsiveness to change despite having more items and a more precise scoring range for each item. This tool may have an inability to detect small but meaningful changes in individuals with severe brain injury.

The FIM includes only five items to assess cognition. This limited cognitive assessment may be inadequate for the assessment of individuals who have experienced TBI (Hall & Johnston 1994). In addition, the FIM is intended to be used in an inpatient rehabilitation setting and is not well suited to ongoing, long-term assessment in community-based settings (Gurka et al. 1999) (TBI).

 

Summary-Functional Independence Measure

Interpretability: The FIM has been well studied for its validity and reliability. It is widely used and has one scoring system, increasing the opportunity for comparison. It is important to remember when interpreting FIM scores that it is an ordinal level scale, not continuous.

Acceptability: Multiple modes in which this measure could be administration have been assessed, including through telephone interviews. The FIM has also been studied for use by proxy respondent. 

Feasibility: Training and education of persons to administer the FIM, in addition to the price of the scale itself, may represent significant cost. Use of interview formats may make the FIM more feasible for longitudinal assessment.

 

Table: Functional Independence Measure Evaluation Summary

Reliability

Validity

Responsiveness

Rigor

Results

Rigor

Results

Rigor

Results

Floor/ceiling

+++

 

 

+++ (TR)

+++ (IO)

+++ (IC)

+++

++

+++

++

++

NOTE: +++=Excellent; ++=Adequate; +=Poor; N/A=insufficient information; TR=Test re-test; IC=Internal Consistency; IO=Interobserver; Varied (re. floor/ceiling effects; mixed results).