Determining normative standards for functional independence measure transitions in rehabilitation

We present a method for determination of normative standards for Functional Independence Measure (FIM) transitions in rehabilitation. Data from 230 consecutive brain-injured patients treated before 1991 were used to characterize transitions in patient FIM values between admission and discharge. The pre-1991 average and standard deviation FIM transitions, computed as a function of admission values, are used as standards ("norms") for comparing rehabilitation transitions among institutions or in one institution over time (say, yearly) and for identifying patients with striking transitions, believed worthy of audit. The evaluation method requires the computation of two statistics, z and W, which compare the actual transitions for patients of one time period (in this instance the 1991 patients) to the expected transitions as computed from the pre-1991 norms. The z and W values indicated that 1991 transitions were neither statistically nor clinically different from pre-1991 ones. Also introduced in the paper are the concepts of Mean Gain, Ideal Gain, and the ratio Mean Gain/Ideal Gain. Ideal Gain is the greatest possible "aggregated" transitions score for a study patient set and the ratio Mean Gain/Ideal Gain may be interpreted as "the degree of ideal rehabilitation transitions achieved."