This standardized scale is probably the best known functional assessment instrument in clinical practice. It has been found to be simple to use and has well established reliability, validity and precision. One shortcoming of the BI consists in the fact that, besides physical activity, other areas of disability are not taken into account. This ordinal scale is subject to inter and intra rater variability and has a bimodal distribution. These instruments advocate a broad view of disability encompassing a social perspective, and stressing that disability is not only limited to physical dependence.
Special attention is given to overall functioning relating to general health and fatiguability.
It is suggested that the FIM can predict the burden of care or the impact of disability on the life of an individual. It is used worldwide for the evaluation of disability in various diseases. In conclusion we can state that the FIM is more sensitive in defining disability, describing more precisely the levels of dependency. According to Granger it is the most useful tool in predicting the burden of care. Some specific items should be added to make this instrument more relevant for MS and before selecting it in an MS database, as the most accurate disability scale.