Functional Independence Measure (FIM) Scoring
The Functional Independence Measure (FIM) is an 18-item, 7-level standardized assessment tool designed to measure the degree of assistance required by disabled patients across six functional domains: self-care, sphincter control, transfers, locomotion, communication, and social cognition. 1
Primary Purpose and Structure
The FIM was developed to uniformly assess disability severity and functional outcomes in rehabilitation settings, particularly for patients recovering from conditions like stroke, spinal cord injury, and other disabling conditions. 1
Key structural components include:
- 18 individual items scored on a 7-level scale, where higher scores indicate greater independence 1, 2
- Six functional domains covering comprehensive activities of daily living 1
- Total possible score range: 18 (complete dependence) to 126 (complete independence) 3
Clinical Applications
Rehabilitation Setting Use
The FIM is the most commonly used functional measure in the United States because it is directly tied to the Centers for Medicare & Medicaid Services prospective payment system. 1
The Veterans Health Administration mandates FIM assessment for all individuals with rehabilitation potential, with data captured in a functional outcomes database. 1
Predictive Value
The FIM serves as a strong predictor of multiple rehabilitation outcomes:
- Discharge functional status - predicts patient capabilities at rehabilitation completion 1
- Discharge destination - helps determine appropriate post-rehabilitation placement 1
- Length of rehabilitation stay - correlates with duration of inpatient rehabilitation needed 1
Outcome Measurement
The FIM assesses the general level of independence across essential functions including eating, grooming, and ambulation, making it valuable for tracking functional recovery over time. 1
The tool demonstrates significant responsiveness, with studies showing 33% average FIM score improvement during rehabilitation, though this varies by diagnosis (traumatic brain injury: 53% improvement; low back pain: 8% improvement). 4
Psychometric Properties
Reliability
The FIM demonstrates excellent interrater reliability when administered by trained clinicians, with total FIM intraclass correlation coefficient (ICC) of 0.96. 2
Specific reliability metrics include:
- Motor domain ICC: 0.96 2
- Cognitive domain ICC: 0.91 2
- Subscale ICC range: 0.89 (social cognition) to 0.94 (self-care) 2
- Individual item Kappa range: 0.53 (memory) to 0.66 (stair climbing) 2
For stroke patients specifically, the FIM shows good interrater agreement, test-retest reliability, and validity. 1
Validity
The FIM demonstrates high internal consistency with Cronbach's alpha of 0.93 at discharge. 4
The tool effectively discriminates patients based on age, comorbidity level, and discharge destination, with adequate construct validity for rehabilitation populations. 4
Telephonic Administration
For stroke patients, the FIM can be reliably administered via telephone with total FIM ICC of 0.97 and subscale ICC ranging from 0.85 to 0.98 (except social cognition, which shows poor correlation). 1
Similar correlations are maintained when administered to patient proxies (caregivers) by telephone. 1
Important Caveats and Limitations
Scoring Assumptions
While FIM scores are frequently used as if sections are of equal importance and intervals are equal, research shows communication is valued more highly than continence, mobility, and self-care (in descending order). 5
However, for practical clinical purposes, FIM scores may be treated as equal interval spacing, and scores from various sections can be added together. 5
Self-Reporting Limitations
Patient self-reported FIM motor scores show only substantial agreement (ICC 0.651) with multidisciplinary assessment in stroke patients. 6
Specific items showing poor agreement (ICC < 0.400) include eating, grooming, bathing, and dressing of the lower body, as patients tend to overrate their performance due to ignorance of limitations or embarrassment. 6
Self-reported FIM should only be considered as an alternative when multidisciplinary assessment is impractical, and results may not be valid for patients with cognitive or communication deficits. 6
Training Requirements
Reliable FIM administration requires formal training and testing of clinicians, with facilities meeting data aggregation reliability criteria showing superior interrater reliability. 2
Certain FIM protocols require specific credentialing that must be adhered to for valid results. 1
Longitudinal Tracking Limitation
Currently, no single functional assessment tool, including the FIM, is used throughout the entire clinical course of stroke care (acute hospital, inpatient rehabilitation, and outpatient care) for comprehensive outcome tracking. 1
The Activity Measure for Post-Acute Care may prove to be a more suitable longitudinal outcome measure for stroke patients, including those with cognitive deficits and aphasia. 1
Comparison with Other Functional Measures
The FIM is often used alongside the Barthel Index, another validated functional assessment tool. 1
Both the Barthel Index and FIM are strong predictors of discharge outcomes, but the FIM's integration with Medicare payment systems makes it the preferred choice in US rehabilitation facilities. 1
For spinal cord injury patients specifically, condition-specific measures like the Spinal Cord Injury Measure and Walking Index in Spinal Cord Injury may better capture functional outcomes important to patients, such as bowel, bladder, and sexual function. 1