THE DEVELOPMENT OF THE FUNCTIONAL-CAPACITY INDEX

Objective: This paper describes the development of the Functional Capa city Index (FCI) and compares it to the Abbreviated Injury Scale (AIS) and the Injury Impairment Scale (IIS). Methods: The FCI maps 1990 AIS injury descriptions into scores that reflect expected levels of reduc ed functional capacity at 1 year after injury, Its development involve d three steps, First, an expert clinical panel identified 10 relevant dimensions of function and defined Levels of capacity within each dime nsion, A group of 114 individuals then rated the relative severity of different levels of function in terms of their impact on daily living, The third step involved clinical experts assigning FCI scores to AIS '90 injury descriptions based on their knowledge of the likely 1-year consequences associated with each injury, As a first step in validatin g the FCI, 1 year postinjury levels of impairment (based on range of m otion and strength) were correlated with FCI, IIS, and AIS scores deri ved for 301, patients with severe lower extremity fractures. Results: Consistency of FCI scores derived within and across dimensions of func tion argue for the conceptual integrity of the index, Non-zero FCI sco res were assigned to only 26% of the 1,272 AIS injury descriptions, in dicating that, for most of the injuries in the AIS dictionary, very li ttle or no residual impairment is expected for the average person at 1 year. FCI scores derived for 301 patients with lower extremity fractu res ranged from 0 to 63 (out of a possible 100 points), A modest corre lation was found between FCI scores and actual levels of impairment ob served at 1 year, Compared with the AIS and the IIS, the FCI appeared to discriminate somewhat better among different levels of function. Co nclusions: Although further empirical validation of the FCI is essenti al before it can be broadly applied, its development represents an imp ortant first step in the generation of an AIS-based measure of expecte d functional outcome. Its validation is encouraged across a variety of settings and injury types.