The Functional Independence Measure (FIM^SM Instrument) and the Functional Independence Measure for Children (WeeFIM® Instrument): Ten Years of Development

The FIM instrument, one of the most widely used functional assessment scales in medical rehabilitation, measures severity of disability in terms of need for assistance. In combination with variables such as length of stay, type and dose of therapy, the FIM instrument provides data on the effectiveness and efficiency of rehabilitative care. Studies evaluating the inter-rater, intra-rater, inter-modal and proxy agreement and internal consistency have found the instrument to be reliable with FIM training and credentialing useful in increasing agreement. Investigations of the validity of the FIM instrument have shown the scale has face validity, construct validity, and predictive validity. The scale is sensitive to change, however, floor and ceiling effects may be seen in some subgroups of patients. FIM scores may be transformed into Rasch interval measures using published charts; however, research showing the utility of these transformed measures is needed. The WeeFIM instrument, originally designed for use with children six months to seven years of age, is a direct adaptation of the FIM instrument. Although only limited studies have evaluated the reliability and validity of this scale, those results have shown that the instrument is valid and reliable.