Objectives: To study group changes over time after traumatic brain injury (TBI).
Design: Prospective cohort.
Setting and participants: TBI Model System Database with 1160 subjects using cohort with complete data.
Main outcome measures: Functional Independence Measure (FIM) and Disability Rating Scale (DRS) at rehabilitation discharge and annually after injury.
Results: Statistically significant differences existed between FIM-total, FIM-Motor, FIM-Cognitive subscales, and DRS at rehabilitation discharge and year 1. Comparisons of year-to-year intervals, years 1 and 3, 1 and 5, and 3 and 5, revealed no statistically significant differences except between years 1 and 3 and 1 and 5 with DRS, and years 1 and 5 with FIM. Including only those more dependent at year 1 revealed statistically significant differences between years 1 and 2 and 1 and 5 on FIM-Cognitive and DRS, but not the FIM-Motor. The proportion of change for FIM and DRS items from year 1 to years 2 and 5 revealed DRS Level of Functioning and Employability items accounted for most DRS change, whereas FIM change was more spread across its components.
Conclusions: DRS is more sensitive to changes during a shorter time period than FIM and seems to be more appropriate for detecting long-term deficits. However, research studies aimed at detecting meaningful changes year to year after TBI may need to use other tools or consider changes among individuals instead of group changes. DRS Level of Function and Employability Items represent complex functions expected to recover later than the more basic DRS items. Sole use of these two DRS items might provide an efficient means of measuring long-term recovery when resources are limited, whereas expansion of these two items might allow greater sensitivity and detail.