Influence of early variables in traumatic brain injury on functional independence measure scores and rehabilitation length of stay and charges

Abstract

Objective: To determine the relationship between early variables (initial Glasgow Coma Scale [GCS] scores, computed tomography [CT] findings, presence of skeletal trauma, age, length of acute hospitalization) and outcome variables (Functional Independence Measure [FIM] scores, rehabilitation length of stay [LOS], rehabilitation charges) in traumatic brain injury (TBI).

Design: Inception cohort.

Setting: University tertiary care rehabilitation center.

Patients: 91 patients with TBI.

Interventions: Inpatient rehabilitation.

Main outcome measures: FIM, rehabilitation LOS, and rehabilitation charges.

Results: Patients in the severely impaired (GCS = 3 to 7) group showed significantly lower (p = .01) mean admission and discharge motor scores (21.26, 39.83) than patients in the mildly impaired (GCS = 13 to 15) group (38.86, 55.29). Cognitive scores were also significantly lower (p < .01) in the severely impaired group on admission (26.73 vs 54.14) and discharge (42.28 vs 66.48). These findings continued to be statistically significant (p < .01) after regression analysis accounted for the other early variables previously listed. Regression analysis also illustrated that longer acute hospitalization LOS was independently associated with significantly lower admission motor (p < .01) and cognitive (p = .05) scores, and significantly higher (p = .01) rehabilitation charges. Patients with CT findings of intracranial bleed with skull fracture had longer total LOS (70.88 vs 43.08 days; p < .05), rehabilitation LOS (30.01 vs 19.68 days; p < .10), and higher rehabilitation charges ($43,346 vs $25,780; p < .05). Paradoxically, those patients in a motor vehicle crash with an extremity bone fracture had significantly higher (p = .002; p = .04 after regression analysis) FIM cognitive scores on admission (48.30 vs 27.28) and discharge (64.74 vs 45.78) than those without a fracture. Finally, data available on rehabilitation admission were used to predict discharge outcomes. The percentage of explained variance for each outcome variable is as follows: discharge FIM motor score, 69.5%; discharge FIM cognitive score, 71.2%; rehabilitation LOS, 54.1%; rehabilitation charges, 61.1%. The most powerful predictor of LOS and charges was the admission FIM motor score (p < .001), followed by CT findings (p = .02) and age (p = .04).

Conclusion: Information readily available on rehabilitation admission, particularly the FIM motor score, may be useful in predicting discharge FIM scores as well as utilization of medical rehabilitation resources. Earlier transfer to rehabilitation may result in higher functional status and lower rehabilitation charges, as well as lower acute hospitalization charges. The presence of extremity fractures encountered during a motor vehicle crash is associated with a more favorable outcome in TBI as evidenced by higher discharge FIM cognitive scores.